- Email: [email protected]
Possible antidepressant effects and mechanism of electroacupuncture in behaviors and hippocampal synaptic plasticity in a depression rat model
BRES : 44522
pp: 127ðcol:fig: : NILÞ
Model7 brain research ] (]]]]) ]]]–]]]
121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 Q1 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180
Available online at www.sciencedirect.com
www.elsevier.com/locate/brainres
Research Report
Possible antidepressant effects and mechanism of electroacupuncture in behaviors and hippocampal synaptic plasticity in a depression rat model Yanling Shea,b,1, Jian Xua,1, Yanhong Duanc, Ning Sud, Yanan Suna, Xiaohua Caod, Lixing Laoe,f, Ruixin Zhangf, Shifen Xua,n a
Shanghai Municipal Hospital of Traditional Chinese Medicine Shanghai, Shanghai University of TCM, Shanghai 200071, China b Guangdong Traditional Medical and Sports Injury Rehabilitation Research Institute, Guangdong No.2 Provincial People's hospital, Guangzhou 510317, China c Key Laboratory of Brain Functional Genomics of Ministry of Education, Shanghai Key Laboratory of Brain Functional Genomics, School of Life Sciences, East China Normal University, Shanghai 200062, China d Guangzhou University of Traditional Chinese Medicine, Guangzhou 510405, China e School of Chinese Medicine, The University of Hong Kong, 10 Sassoon Road, Pokfulam, Hong Kong f University of Maryland, School of Medicine, Center for Integrative Medicine, Baltimore, MD 21201, USA
art i cle i nfo
ab st rac t
Article history:
Increasing evidences show that hippocampal synaptic plasticity plays a crucial role in the
Accepted 16 October 2015
pathogenesis of depression. The objective of this study was to determine whether electroacupuncture (EA) in the Wistar Kyoto (WKY) rat model of depression would exert antidepres-
Keywords:
sant effects and whether this effect would be associated with changes in hippocampal synaptic
Electroacupuncture
plasticity. Male WKY rats were randomly divided into three groups (EA, sham EA, and blank
Depresson
control); Wister rats were used as normal control group. Treatment with EA was performed at
Behavior
Baihui (GV20) and Yintang (EX-HN3) once daily for 3 weeks. Forced swimming test (FST), open
Synaptic plasticity
field test (OFT), and Morris water maze (MWM) were evaluated after 21-day intervention. Longterm potentiation (LTP) was evoked at Schaffer collateral-CA1 synapses in hippocampal slices in vitro. EA treatment significantly reduced immobility time in FST. MWM test showed a significant downward trend in escape latency time from the second to fifth days of experiment, and a higher frequency of crossing the missing quadrant platform in normal control and EA vs other groups. Impaired LTP was detected in Schaffer collateral-CA1 synapses in blank control and sham EA groups. In the western blot, the expression of GluN2B showed significant increase in EA vs sham EA and blank control groups. EA was able to improve depression-like behaviors and reverse the impairment of LTP, which were likely mediated by GluN2B in the hippocampus. & 2015 Published by Elsevier B.V.
n
Corresponding author. E-mail address: [email protected] (S. Xu). 1 These authors made same work for this article.
http://dx.doi.org/10.1016/j.brainres.2015.10.033 0006-8993/& 2015 Published by Elsevier B.V.
Please cite this article as: She, Y., et al., Possible antidepressant effects and mechanism of electroacupuncture in behaviors and hippocampal synaptic plasticity in a depression rat model. Brain Research (2015), http://dx.doi.org/10.1016/j. brainres.2015.10.033
181 182 183 184 185 186
BRES : 44522
2
187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246
brain research ] (]]]]) ]]]–]]]
1.
Introduction
Depression is a common neuropsychiatric disorder with a lifetime prevalence rate of 16.5% (Aung et al., 2013). It is characterized by low mood, cognitive impairment, low selfworth, loss of interest or appetite, and is accompanied by the feeling of guilt and attempt to suicide. It adversely affects patients' ability to work, lifestyle, quality of sleep, income, and cost (Aung et al., 2013). Antidepressant drugs present first choice of clinical therapy over the past 50 years,. However, approximately one-third to onehalf of patients did not respond to antidepressant treatment (Bschor et al., 2014). In addition, nearly all antidepressants require 4–6 weeks to exert their therapeutic effects and their adverse effects cannot be ignored (Lavergne and Jay, 2010). Acupuncture is one of the complementary and alternative modalities for the treatment of various psychiatric and emotional disorders including Alzheimer disease, generalized anxiety disorder, posttraumatic stress disorder, sleep disorders, major depression, etc. (Aung et al., 2013; Wang et al., 2012). Experimental studies in humans have supported the idea that acupuncture is a safe and highly effective therapy in treating depression. A recent randomized controlled trial (RCT) used Patient Health Questionnaire to evaluate the effects of acupuncture and counseling on depression in 755 patients in primary care. Results indicated that both acupuncture and counseling significantly reduced depression at 3 months as compared to usual care alone (MacPherson et al., 2013). Another RCT showed that acupuncture combined with selective serotonin reuptake inhibitors (SSRIs) significantly improved the 17-item Hamilton Depression Rating Scale scores as compared to SSRIs alone over the 6-week period (Wang et al., 2014). However, the mechanisms of treatment with electroacupuncture (EA) on depression were not well understood. Neural plasticity, especially hippocampal synaptic plasticity, is thought to contribute to learning and memory (Foy, 2011). Impaired plasticity leads to cognitive deficits and memory loss. It is well known that learning ability decreased in depressive subjects. Pharmacological intervention that manipulates synaptic plasticity promotes the formation of memory. Zhang et al. (2012) reported that in corticosterone-stressed rats, hippocampal cell proliferation significantly decreased, and treatment with Lycium barbarum increased immobility time in forced swimming test (FST), restored the reduced spine density and the decreased levels of (postsynaptic density-95) PSD-95 in the hippocampus. It has also been reported (Luo et al., 2014) that chronic unpredictable mild stress model rats resulted in damaging the memory, impairing long-term potentiation (LTP), and downregulating PSD-95. The treatment with electroconvulsive shock under anesthesia improved memory possibly through reversing the excessive changes in hippocampal synaptic plasticity. LTP is considered as a cellular mechanism of memory formation and its induction required increased numbers of α-amino-3-hydroxy-5-methyl-4isoxazolepropionic acid receptors (AMPARs) and the activation of N-methyl-D-aspartate receptors (NMDARs) (Foy, 2011). In this study, a well-established model of depression, the putative genetic Wistar Kyoto (WKY) rat model of co-morbid depression and anxiety, was used (López-Rubalcava and Lucki, 2000; Rittenhouse et al., 2002), to investigate the effect
and mechanism of EA on depression. Behavioral studies including FST, OFT, and Morris water maze (MWM) test were used to evaluate depression-like behavior. Electrophysiological study was used to record LTP evoked at Schaffer collateral-CA1 synapses in the hippocampus, and western blot was used to measure the expression of hippocampal AMPAR and NMDAR subunits. It was hypothesized that treatment with EA will modulate the expression of hippocampus AMPAR and NMDAR, and LTP to improve depressionlike behavior.
2.
Results
2.1.
FST
The results of FST are shown in Fig. 1. Duration of immobility was significantly (Po0.01) longer in the blank controls (WKY rats, column 2) than in the normal controls (Wistar rats, column 1), indicating that WKY rats showed depression-like behavior. Interestingly, the duration of immobility was significantly (Po0.05) shorter in the EA group (95.11710.28 s) than in the blank control and sham EA groups (119.4979.12 s and 114.6377.07 s, respectively), suggesting that treatment with EA improves the depression-like behavior.
2.2.
OFT
The results of the OFT are shown in Fig. 2. The total distance (Fig. 2A), mean speed (Fig. 2B), and distance traveled within the central area (Fig. 2C) were significantly (Po0.01) shorter in the blank control (WKY rats) than in the normal control (Wistar rats). Duration of time spent by the rats in the central area was significantly (Po0.05) shorter in the blank control and sham EA than in the normal control (Fig. 2D). The number of rearing and grooming incidents is significantly (Po0.01) smaller in the blank control than in the normal control (Fig. 2E). These data indicate that WKY rats showed depression-like behavior. Although statistically significant differences were not found among the EA, blank control, and sham EA groups in any of these parameters, EA showed
Fig. 1 – Forced swimming test in rats after 3-week intervention. Data were expressed as mean7SEM. **Po0.01 compared to normal control; #Po0.05 compared to treatment with EA; ##Po0.01 compared to treatment with EA. EA, electroacupuncture; SEM, standard error of mean.
Please cite this article as: She, Y., et al., Possible antidepressant effects and mechanism of electroacupuncture in behaviors and hippocampal synaptic plasticity in a depression rat model. Brain Research (2015), http://dx.doi.org/10.1016/j. brainres.2015.10.033
247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306
BRES : 44522 brain research ] (]]]]) ]]]–]]]
307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366
3
Fig. 2 – Open field test in rats after 3-week intervention. Total distance (A), mean speed (B), central activity distance (C), duration of time spent by rats in the central area (D), and the number of rearing and grooming incidents (E) in the open field test. Data were expressed as mean7SEM. *Po0.05 compared to normal control; **Po0.01 compared to normal control. SEM, standard error of mean.
sham EA did not influence the learning ability. Although the duration was the same between EA and sham EA control during days 1–2, it became significantly (Po0.01) shorter in the EA group than in the sham EA control at day 5 (Fig. 3). These data demonstrate that treatment with EA improved the impaired learning ability in WKY rats.
2.4.
Fig. 3 – Escape latency of Morris water maze test in rats after 3-week intervention. Data were expressed as mean7SEM. ** Po0.01 compared to normal control; ##Po0.01 compared to treatment with EA. EA, electroacupuncture; SEM, standard error of mean.
an obvious tendency toward increased duration of time spent by rats in the central area.
2.3.
MWM test
The escape latency to find the target platform became gradually shorter in normal control Wistar rats, demonstrating that Wistar rats have normal learning ability during the MWM test (Fig. 3). The duration was significantly (Po0.01) longer in the blank and sham EA controls than in the normal control during days 1–5. This indicates that WKY rats showed a learning impairment and
Electrophysiological recording
The results of hippocampal Schaffer collateral-CA1 LTP Q2 induced by the 100 Hz tetanus for 1 s are shown in Fig. 4. The fEPSP slope was up to 136.0272.98% and 122.2872.58% in the normal control and EA groups, respectively. Tetanic stimulation failed to induce LTP in the blank control (107.2573.33%) and sham EA group (102.5772.35%).
2.5.
Western blot
The expression of GluN2B protein was significantly lower in the blank control and sham EA groups (Fig. 5). Treatment with EA restored the expression of GluN2B protein to levels observed in the normal control group. No differences were found in GluN1, GluN2A, GluR1, and GluR2 comparisons among all the groups.
3.
Discussion
The present study evaluated the antidepressive effects of EA therapy in the genetic WKY rat model of depression. The
Please cite this article as: She, Y., et al., Possible antidepressant effects and mechanism of electroacupuncture in behaviors and hippocampal synaptic plasticity in a depression rat model. Brain Research (2015), http://dx.doi.org/10.1016/j. brainres.2015.10.033
367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426
BRES : 44522
4
427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486
brain research ] (]]]]) ]]]–]]]
Fig. 4 – Induction of LTP in the hippocampal Schaffer collateral-CA1 in rats after 3-week intervention. fEPSP slopes were plotted as a percentage of baseline (A). The fEPSP slope of the preceding 10 min (duration 80–90 min) was averaged (B). Data were expressed as mean7SEM. **Po0.01 compared to the normal control; ##Po0.01 compared to treatment with EA. EA, electroacupuncture; fEPSP, field excitatory postsynaptic potential; LTP, long-term potentiation; SEM, standard error of mean.
Fig. 5 – Expression of hippocampal AMPAR and NMDAR subunits protein in rats after 3-week intervention. Western blot bands of expression of GluR1, GluR2, GluN1, GluN2A, GluN2B, and GAPDH protein. AMPAR, α-amino-3-hydroxy-5methyl-4-isoxazolepropionic acid receptor; GAPDH, Glyceraldehyde 3-phosphate dehydrogenase; NMDAR, Nmethyl-D-aspartate receptor.
results showed that 3-week EA intervention significantly increased the immobility time in FST as compared to the sham EA control. EA showed a obvious tendency to increase the duration spent by rats in the central area of an open field, although it did not show any effects on total distance, mean speed, central activity distance, and the number of rearing and grooming. These data demonstrated that treatment with EA improved depression-like behavior in WKY depression rat model. These results were in agreement with a previous study (Xu et al., 2011) using unpredictable chronic mild stress (UCMS)-induced depression rat model, in which treatment
with EA increased the consumption of sucrose and the number of crossing and rearing in OFT, indicating improvements in depression-like behaviors. It is noted that EA did not significantly improve the number of rearing and the locomotion activity in the WKY model as opposed to the UCMS model. This suggests that EA may produce differential effects in different models. Previous studies also demonstrated that EA improved neuropathic pain-induced depression-like behavior (Li et al., 2014). These studies in animal models support the clinical data that acupuncture is promising for the treatment of depression (Bosch et al., 2015). The present study also demonstrated that WKY rat model showed significant learning deficits and EA significantly enhanced the learning ability. In addition, treatment with EA improved the learning ability in UCMS-induced depression model (Bao et al., 2014). This intervention ameliorated ethanol-induced impairments of spatial learning and memory (Lu et al., 2014). However, the mechanisms of EA on learning ability are not understood. In recent years, converging evidence have shown that antidepressants and antidepressive therapies modulate hippocampus synaptic plasticity to improve memory (Paizanis et al., 2007; Pompili et al., 2013). LTP and long-term depression are two forms of synaptic plasticity and LTP is considered the cellular mechanism that underlies learning and memory. Exposure to acute and chronic stress was proven to impair hippocampal LTP, resulting in working memory impairment in animal studies (Bhagya et al., 2011; Dale et al., 2014; Quan et al., 2011; Shakesby et al., 2002). For example, vortioxetine (a 5-HT receptor antagonist) prevented the 5-HT-induced increase in the inhibitory postsynaptic potentials recorded from CA1 pyramidal cells, and enhanced theta burst LTP in hippocampal slices, and showed positive effects against cognitive dysfunction in major depression disorder model of rodents. To further explore the underlying mechanisms of treatment with EA on learning and memory, hippocampal Schaffer collateral-CA1 LTP was induced by the 100Hz tetanus in vitro. These data showed that treatment with EA significantly increased the slope of fEPSP as compared to the sham EA control. These suggest that EA may improve spatial
Please cite this article as: She, Y., et al., Possible antidepressant effects and mechanism of electroacupuncture in behaviors and hippocampal synaptic plasticity in a depression rat model. Brain Research (2015), http://dx.doi.org/10.1016/j. brainres.2015.10.033
487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546
BRES : 44522 brain research ] (]]]]) ]]]–]]]
547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606
learning and memory ability by enhancing the hippocampal LTP. The manner in which EA enhances LTP in the hippocampus warrants further investigation. Previous studies suggest that EA intervention may modulate Q3 hippocampal galanin (Modi et al., 2014) and dopamine (Dupin et al., 2006) to alleviate depression. Both AMPARs and NMDARs are involved in synaptic plasticity of LTP and Long term depression (LTD). AMPARs and NMDARs were further detected to determine the particular receptor subunits that might be related to the modulation of EA of hippocampal CA1 LTP in depressive rats. These results showed that the expression of GluN2B was increased after EA intervention. Accumulating evidences suggest that the enhancement of GluN2B subunits plays a critical role in the improvement of LTP in the CA1 region as well as learning and memory performance (Burgdorf et al., 2013; Shipton and Paulsen, 2014; Tang et al., 2001; Yilmaz et al., 2011). For instance (Yilmaz et al., 2011), venlafaxine and serotonin–norepinephrine reuptake inhibitor, improved depressionlike behaviors, and the depression reduced the expression of GluN2B in the hippocampus. Further, GLYX-13, a novel NMDAR glycine-site functional partial agonist, produced striking antidepressant effects accompanied by an enhancement in the magnitude of LTP at Schaffer collateral-CA1 synapses in vitro, and an increase in GluN2B in cell membrane (Burgdorf et al., 2013). Upregulation of GluN2B in CA1 pyramidal neurons results in an LTP enhancement (Müller et al., 2013) Together, these data suggest that treatment with EA may increase the expression of GluN2B to promote LTP and alleviate depression-like behavior. Additionally, this study did not find any difference in GluN1, GluN2A, GluR1, and GluR2 in the WKY rat model and EA-treated rats. In contrast, Martisova et al. (2012) reported that GluN1 and GluN2A were upregulated in an early-life stressed (maternal separation) rats; the expression of GluN2B, GluR1, and GluR2/3 were not changed in this model. Venlafaxine successfully reversed the increased expression of GluN1 and GluN2A. The difference in GluN1, GluN2a, and Glu2B between the present and the previous studies may be accounted for by the distinctive models. The relative small number of rats in each group may cause some bias of behavioral tests. In summary, these results demonstrate that treatment with EA significantly improved depression-like behavior in WKY depression rat model. This effect may be related to the increased NMDAR subunit expression of GluN2B and the enhanced LTP in the hippocampus.
4.
Experimental procedure
4.1.
Animals
Four-week-old male WKY and Wistar rats were obtained from Vital River Laboratory Animal Technology Company (Beijing, China). WKY rats showed a series of depressive symptoms that mimic those in humans such as exaggerated immobility in the FST, low level of social activities, decreased hippocampal volume as well as elevated rapid eye movement sleep in comparison to their Wistar control rats (DaSilva et al., 2011; Paré, 1989; Tizabi et al., 2010). The rats were kept under standard conditions (2272 1C, relative humidity 50–60%, alternate dark-
5
light cycles with light on at 8:00 am, food and tap water were available ad libitum). All rats were adapted to the environment for 1 week before the experiment. All procedures were performed according to the Suggestions for the Care and Use of Laboratory Animals formulated by the Ministry of Science and Technology of People's Republic of China and approved by the Animal Ethics Committee at Shanghai Municipal Hospital of Traditional Chinese Medicine, Shanghai, China.
4.2.
Experimental design
Male WKY rats were randomly categorized into three groups: EA group (n ¼7), sham EA group (n¼ 6), and blank control group (n¼ 6). The Wistar rats (n¼ 7), as an outbred albino rat strain from WKY, were used as normal control in this study. Rats in the EA group received 21 days of treatment with EA as reported (Lao et al., 2004; Xu et al., 2011) earlier: each rat was placed under an inverted clear 5″ 8″ 11″ plastic chamber without any restriction or anesthetic, disposable, sterile, and stainless steel acupuncture needles (diameter, 0.25 mm; length 25 mm; Suzhou Medical Appliance Factory, Suzhou, China) were inserted at Baihui (GV20) and Yintang (EX-HN3) at a depth of approximately 0.5 mm. An electrostimulator, Huatuo's Acupoint Nerve Stimulator (SDZ-V; Huatuo Medical Technology Co., Ltd. Suzhou, China), was connected, and electrical current was delivered to the needles. The anode was inserted into EX-HN3 and the cathode was inserted into GV20. The frequency of EA was held constant at 2 Hz (2 pulses/s) and pulse width was 0.2 ms. The intensity was started from 0.1 mA and adjusted to 3 mA, resulting in a manifestation of gentle head nodding, which is tolerated by rats. The needles were retained for 15 min. Sham EA group received no electrical stimulation: the needles were pasted at the surface of GV20 and EX-HN3 to make the needles touch the skin but not insert the acupoints. Normal control and blank control groups were not given any treatment.
4.3.
Behavioral tests
After completing the treatment on day 21, the rats were evaluated in the behavioral tests of FST, OFT, and MWM.
4.4.
FST
Briefly, in FST test (Kitada et al., 1981), rats were individually placed into glass cylinders (30 cm diameter 40 cm height) filled with water (23–25 1C) to a depth of 30 cm so that the rats could not touch the bottom of the cylinder with their hind limbs. Water was changed in between rats. On day 1, rats were placed in the water-filled cylinder for 5 min. It was pretested and was not recorded. After 24 h, rats were placed into water again for a 5-min test. The test session was videotaped and the time of immobility was measured.
4.5.
OFT
The OFT apparatus (Gray et al., 1975) was a square black box (50 cm 50 cm 100 cm) and was placed in dim light. The rat was placed in the box to move freely for 5 min, and all
Please cite this article as: She, Y., et al., Possible antidepressant effects and mechanism of electroacupuncture in behaviors and hippocampal synaptic plasticity in a depression rat model. Brain Research (2015), http://dx.doi.org/10.1016/j. brainres.2015.10.033
607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666
BRES : 44522
6
667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726
brain research ] (]]]]) ]]]–]]]
activities were recorded using a video camera mounted above the open field and recored in real time. Total distance, mean speed, time and distance in central area, and incidents of rearing and grooming were analyzed using the motion tracking system.
4.6.
MWM test
The ability of spatial learning and memory was evaluated using the MWM (Morris, 1984). The maze was a circular pool filled with water (22–25 1C) and divided into four equal quadrants. A circular platform was located 2 cm below the water surface on a fixed location. Rats were given four trials a day for five consecutive days. Once a rat climbed onto the platform and remained on it for 10 s, the trial was terminated. If the rat failed to reach the platform within 90 s, it was gently guided to the platform and allowed to stay on it for 10 s. The escape latency and distance traveled were recorded using a video tracking system. In probe test, on day 5, the hidden platform was removed and the rat was allowed to explore the pool for 90 s. The platform crossing frequencies in the target quadrant were measured.
4.7.
Electrophysiological recording
After the behavioral tests, rats were anesthetized using sodium pentobarbital and decapitated. The brain was removed immediately and placed in 0–4 1C oxygenated artificial cerebrospinal fluid (ACSF) containing 121 mM NaCl, 2.3 mM KCl, 0.5 mM CaCl2, 1.3 mM MgSO4, 1.0 mM NaH2PO4, 26.2 mM NaHCO3, and 11 mM D-glucose. Hippocampus was rapidly removed and both the hemispheres were dissected on ice; one side was placed in liquid nitrogen for the detection of protein and the other side was used for electrophysiological recording. Transverse hippocampal slices (400 mm) were cut using a vibratome in ice-cold cutting solution. Slices were transferred to a incubating chamber filled with ACSF containing 119 mM NaCl, 2.3 mM KCl, 2.5 mM CaCl2, 1.3 mM MgSO4, 1.0 mM NaH2PO4, 26.2 mM NaHCO3, and 11 mM D-glucose, and incubated for 1 h at 31 1C before recording. ACSF was perfused with 95% O2 and 5% CO2 continuously. A bipolar tungsten stimulating electrode was placed in the stratum radiatum of CA1 and the field excitatory postsynaptic potentials (fEPSPs) were recorded using a glass microelectrode filled with 0.5 M natrium aceticum (4–8 MΩ). Test stimuli were delivered every 15 s. After recording a stable baseline for 30 min, LTP was induced by a tetanic stimuli at 100 Hz for 1 s. fEPSP continued to be recorded for 60 min after highfrequency stimulation was administered. Data were recorded recorded using a Multiclamp 700B amplifier and digitized with a Digidata 1322 A (Axon Instruments, Foster City, CA).
4.8.
Western blot
Tissues were homogenized in an extraction buffer containing 2 sodium dodecyl sulfate (SDS), protease inhibitor mixture, and phosphatase inhibitor mixture. The homogenates were centrifuged at 13,000 rpm for 15 min at 4 1C. The same amount of total proteins was loaded on the gels, separated on 10% SDSpolyacrylamide gel electrophoresis, and transferred onto poly
(vinylidene fluoride) membranes. Blots were blocked in blocking buffer [1 Tris-buffered saline (TBS), 0.1% Tween-20 with 5% nonfat dry milk) for 1 h at room temperature. After washing, blots were incubated overnight at 4 1C with primary antibodies against GluR1 (1:5000; Millipore, Billerica, MA,USA), GluR2 (1:1000; Epitomics, Burlingame, CA), NMDAR (GluN1, 1:1000; Millipore,Billerica,MA,USA), NMDAR (GluN2A, 1:1500; Millipore, Billerica, MA, USA), and NMDAR (GluN2B, 1:1500; Millipore, Billerica, MA, USA). After washing twice in TBS-Tween 20 (TBS-T) and thrice in 1% milk TBS-T for 5 min each, blots were incubated with goat anti-mouse or anti-rabbit secondary antibody for 1 h at room temperature. Band intensity was detected using LI-COR Odyssey Infrared Fluorescence Scanning Imaging System(LI-COR, Lincoln, NE,USA).
4.9.
Statistical analysis
Data were analyzed using SPSS16.0 for Windows 7. All data were expressed as mean7standarddeviation. Comparisons between different groups were performed using one-way analysis of variance, followed by least significant difference test for post-hoc analyses. Pr 0.05 was considered statistically significant.
r e f e r e n c e s
Aung, S.K., Fay, H., Rd, H.R., 2013. Traditional Chinese medicine as a basis for treating psychiatric disorders: a review of theory with illustrative cases. Med. Acupunct. 25, 398–406. Bao, W., Jiao, S., Lu, J., Tu, Y., Song, Y., Wu, Q., 2014. Effect of electroacupuncture intervention on learning-memory ability Q4 and injured hippocampal neurons in depression rats. Acupunct. Res. 39, 136–141. Bhagya, V., Srikumar, B., Raju, T., Rao, B.S., 2011. Chronic escitalopram treatment restores spatial learning, monoamine levels, and hippocampal long-term potentiation in an animal model of depression. Psychopharmacology 214, 477–494. Bosch, P., van den Noort, M., Staudte, H., Lim, S., 2015. Schizophrenia and depression: a systematic review of the effective- Q5 ness and the working mechanisms behind acupuncture. EXPLORE: J. Sci. Heal.11281–291 Bschor, T., Bauer, M., Adli, M., 2014. Chronic and treatment Q6 resistant depression. Dtsch. Arztebl. Int. 111, 766776 771-U28. Burgdorf, J., Zhang, X.-l, Nicholson, K.L., Balster, R.L., Leander, J. D., Stanton, P.K., Gross, A.L., Kroes, R.A., Moskal, J.R., 2013. GLYX-13, a NMDA receptor glycine-site functional partial agonist, induces antidepressant-like effects without ketamine-like side effects. Neuropsychopharmacology 38, 729–742. Dale, E., Zhang, H., Leiser, S.C., Xiao, Y., Lu, D., Yang, C.R., Plath, N., Sanchez, C., 2014. Vortioxetine disinhibits pyramidal cell function and enhances synaptic plasticity in the rat hippocampus. J. Psychopharmacol. 28, 891–902. DaSilva, J., Husain, E., Lei, Y., Mann, G., Tejani-Butt, S., Morrison, A., 2011. Social partnering significantly reduced rapid eye movement sleep fragmentation in fear-conditioned, stresssensitive Wistar-Kyoto rats. Neuroscience 199, 193–204. Dupin, N., Mailliet, F., Rocher, C., Kessal, K., Spedding, M., Jay, T. M., 2006. Common efficacy of psychotropic drugs in restoring stress-induced impairment of prefrontal plasticity. Neurotox. Res. 10, 193–198. Foy, M.R., 2011. Ovarian hormones, aging and stress on hippocampal synaptic plasticity. Neurobiol. Learn. Mem. 95, 134–144.
Please cite this article as: She, Y., et al., Possible antidepressant effects and mechanism of electroacupuncture in behaviors and hippocampal synaptic plasticity in a depression rat model. Brain Research (2015), http://dx.doi.org/10.1016/j. brainres.2015.10.033
727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786
BRES : 44522 brain research ] (]]]]) ]]]–]]]
787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833
Gray, J.A., Drewett, R.F., Lalljee, B., 1975. Effects of neonatal castration and testosterone injection on adult open-field behaviour in rats with atypical sex difference in defecation. Anim. Behav. 23, 773–778. Kitada, Y., Miyauchi, T., Satoh, A., Satoh, S., 1981. Effects of antidepressants in the rat forced swimming test. Eur. J. Pharmacol. 72, 145–152. Lo´pez-Rubalcava, C., Lucki, I., 2000. Strain differences in the behavioral effects of antidepressant drugs in the rat forced swimming test. Neuropsychopharmacology 22, 191–199. Lao, L., Zhang, R.-X., Zhang, G., Wang, X., Berman, B.M., Ren, K., 2004. A parametric study of electroacupuncture on persistent hyperalgesia and Fos protein expression in rats. Brain Res. 1020, 18–29. Q7 Lavergne, F., Jay, T.M., 2010. A new strategy for antidepressant prescription. Front. Neurosci.4. Li, Q., Yue, N., Liu, S.-B., Wang, Z.-F., Mi, W.-L., Jiang, J.-W., Wu, G.C., Yu, J., Wang, Y.-Q., 2014. Effects of chronic electroacupuncture on depression-and anxiety-like behaviors in rats with chronic neuropathic pain. Evid.-Based Complement. Altern. Med.2014. Lu, B., Ma, Z., Cheng, F., Zhao, Y., Zhang, X., Mao, H., Shen, X., Liu, S., 2014. Effects of electroacupuncture on ethanol-induced impairments of spatial learning and memory and Fos expression in the hippocampus in rats. Neurosci. Lett. 576, 62–67. Luo, J., Min, S., Wei, K., Cao, J., Wang, B., Li, P., Dong, J., Liu, Y., 2014. Propofol prevents electroconvulsive-shock-induced memory impairment through regulation of hippocampal synaptic plasticity in a rat model of depression. Neuropsychiatr. Dis. Treat. 10, 1847. Mu¨ller, L., Tokay, T., Porath, K., Ko¨hling, R., Kirschstein, T., 2013. Enhanced NMDA receptor-dependent LTP in the epileptic CA1 area via upregulation of NR2B. Neurobiol. Dis. 54, 183–193. MacPherson, H., Richmond, S., Bland, M., Brealey, S., Gabe, R., Hopton, A., Keding, A., Lansdown, H., Perren, S., Sculpher, M., 2013. Acupuncture and counselling for depression in primary care: a randomised controlled trial. PLoS Med. 10, e1001518. Martisova, E., Solas, M., Horrillo, I., Ortega, J.E., Meana, J.J., Tordera, R.M., Ramı´rez, M.J., 2012. Long lasting effects of earlylife stress on glutamatergic/GABAergic circuitry in the rat hippocampus. Neuropharmacology 62, 1944–1953. Modi, K.K., Jana, A., Ghosh, S., Watson, R., Pahan, K., 2014. A physically-modified saline suppresses neuronal apoptosis, attenuates tau phosphorylation and protects memory in an animal model of Alzheimer’s disease. PLoS One 9, e103606. Morris, R., 1984. Developments of a water-maze procedure for studying spatial learning in the rat. J. Neurosci. Methods 11, 47–60. Paizanis, E., Hamon, M., Lanfumey, L., 2007. Hippocampal neurogenesis, depressive disorders, and antidepressant therapy. Neural Plast.2007.
7
Pare´, W.P., 1989. “Behavioral despair” test predicts stress ulcer in WKY rats. Physiol. Behav. 46, 483–487. Pompili, M., Serafini, G., Innamorati, M., Venturini, P., Fusar-Poli, P., Sher, L., Amore, M., Girardi, P., 2013. Agomelatine, a novel intriguing antidepressant option enhancing neuroplasticity: a critical review. World J. Biol. Psychiatry 14, 412–431. Quan, M.-N., Zhang, N., Wang, Y.-Y., Zhang, T., Yang, Z., 2011. Possible antidepressant effects and mechanisms of memantine in behaviors and synaptic plasticity of a depression rat model. Neuroscience 182, 88–97. Rittenhouse, P.A., Lo´pez-Rubalcava, C., Stanwood, G.D., Lucki, I., 2002. Amplified behavioral and endocrine responses to forced swim stress in the Wistar–Kyoto rat. Psychoneuroendocrinology 27, 303–318. Shakesby, A.C., Anwyl, R., Rowan, M.J., 2002. Overcoming the effects of stress on synaptic plasticity in the intact hippocampus: rapid actions of serotonergic and antidepressant agents. J. Neurosci. 22, 3638–3644. Shipton, O.A., Paulsen, O., 2014. GluN2A and GluN2B subunitcontaining NMDA receptors in hippocampal plasticity. Philos. Trans. R. Soc. Lond. B: Biol. Sci. 369, 20130163. Tang, Y.-P., Wang, H., Feng, R., Kyin, M., Tsien, J., 2001. Differential effects of enrichment on learning and memory function in NR2B transgenic mice. Neuropharmacology 41, 779–790. Tizabi, Y., Hauser, S.R., Tyler, K.Y., Getachew, B., Madani, R., Sharma, Y., Manaye, K.F., 2010. Effects of nicotine on depressive-like behavior and hippocampal volume of female WKY rats. Prog. Neuro-Psychopharmacol. Biol. Psychiatry 34, 62–69. Wang, T., Wang, L., Tao, W., Chen, L., 2014. Acupuncture combined with an antidepressant for patients with depression in hospital: a pragmatic randomised controlled trial. Acupunct. Med.32308–312acupmed-2013-010469 Wang, Z., Nie, B., Li, D., Zhao, Z., Han, Y., Song, H., Xu, J., Shan, B., Lu, J., Li, K., 2012. Effect of acupuncture in mild cognitive Q8 impairment and Alzheimer disease: a functional MRI studyPLos One7e42730 Xu, S., Li, S., Shen, X., Meng, X., Lao, L., 2011. Effects of electroacupuncture on depression in a rat model. Acupunct. Electrother. Res. 36, 259–273. Yilmaz, N., Demirdas, A., Yilmaz, M., Sutcu, R., Kirbas, A., Cure, M.C., Eren, I˙., 2011. Effects of venlafaxine and escitalopram treatments on NMDA receptors in the rat depression model. J. Membr. Biol. 242, 145–151. Zhang, E., Yau, S.Y., Lau, B.W.M., Ma, H., Lee, T., Chang, R.C.-C., So, K.F., 2012. Synaptic Plasticity, But Not Hippocampal Neurogenesis, Mediated the Counteractive Effect of Wolfberry on Depression in Rats1. Cell Transplant. 21, 2635–2649.
Please cite this article as: She, Y., et al., Possible antidepressant effects and mechanism of electroacupuncture in behaviors and hippocampal synaptic plasticity in a depression rat model. Brain Research (2015), http://dx.doi.org/10.1016/j. brainres.2015.10.033
834 835 836 837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876 877 878 879
pp: 127ðcol:fig: : NILÞ
Model7 brain research ] (]]]]) ]]]–]]]
121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 Q1 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180
Available online at www.sciencedirect.com
www.elsevier.com/locate/brainres
Research Report
Possible antidepressant effects and mechanism of electroacupuncture in behaviors and hippocampal synaptic plasticity in a depression rat model Yanling Shea,b,1, Jian Xua,1, Yanhong Duanc, Ning Sud, Yanan Suna, Xiaohua Caod, Lixing Laoe,f, Ruixin Zhangf, Shifen Xua,n a
Shanghai Municipal Hospital of Traditional Chinese Medicine Shanghai, Shanghai University of TCM, Shanghai 200071, China b Guangdong Traditional Medical and Sports Injury Rehabilitation Research Institute, Guangdong No.2 Provincial People's hospital, Guangzhou 510317, China c Key Laboratory of Brain Functional Genomics of Ministry of Education, Shanghai Key Laboratory of Brain Functional Genomics, School of Life Sciences, East China Normal University, Shanghai 200062, China d Guangzhou University of Traditional Chinese Medicine, Guangzhou 510405, China e School of Chinese Medicine, The University of Hong Kong, 10 Sassoon Road, Pokfulam, Hong Kong f University of Maryland, School of Medicine, Center for Integrative Medicine, Baltimore, MD 21201, USA
art i cle i nfo
ab st rac t
Article history:
Increasing evidences show that hippocampal synaptic plasticity plays a crucial role in the
Accepted 16 October 2015
pathogenesis of depression. The objective of this study was to determine whether electroacupuncture (EA) in the Wistar Kyoto (WKY) rat model of depression would exert antidepres-
Keywords:
sant effects and whether this effect would be associated with changes in hippocampal synaptic
Electroacupuncture
plasticity. Male WKY rats were randomly divided into three groups (EA, sham EA, and blank
Depresson
control); Wister rats were used as normal control group. Treatment with EA was performed at
Behavior
Baihui (GV20) and Yintang (EX-HN3) once daily for 3 weeks. Forced swimming test (FST), open
Synaptic plasticity
field test (OFT), and Morris water maze (MWM) were evaluated after 21-day intervention. Longterm potentiation (LTP) was evoked at Schaffer collateral-CA1 synapses in hippocampal slices in vitro. EA treatment significantly reduced immobility time in FST. MWM test showed a significant downward trend in escape latency time from the second to fifth days of experiment, and a higher frequency of crossing the missing quadrant platform in normal control and EA vs other groups. Impaired LTP was detected in Schaffer collateral-CA1 synapses in blank control and sham EA groups. In the western blot, the expression of GluN2B showed significant increase in EA vs sham EA and blank control groups. EA was able to improve depression-like behaviors and reverse the impairment of LTP, which were likely mediated by GluN2B in the hippocampus. & 2015 Published by Elsevier B.V.
n
Corresponding author. E-mail address: [email protected] (S. Xu). 1 These authors made same work for this article.
http://dx.doi.org/10.1016/j.brainres.2015.10.033 0006-8993/& 2015 Published by Elsevier B.V.
Please cite this article as: She, Y., et al., Possible antidepressant effects and mechanism of electroacupuncture in behaviors and hippocampal synaptic plasticity in a depression rat model. Brain Research (2015), http://dx.doi.org/10.1016/j. brainres.2015.10.033
181 182 183 184 185 186
BRES : 44522
2
187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246
brain research ] (]]]]) ]]]–]]]
1.
Introduction
Depression is a common neuropsychiatric disorder with a lifetime prevalence rate of 16.5% (Aung et al., 2013). It is characterized by low mood, cognitive impairment, low selfworth, loss of interest or appetite, and is accompanied by the feeling of guilt and attempt to suicide. It adversely affects patients' ability to work, lifestyle, quality of sleep, income, and cost (Aung et al., 2013). Antidepressant drugs present first choice of clinical therapy over the past 50 years,. However, approximately one-third to onehalf of patients did not respond to antidepressant treatment (Bschor et al., 2014). In addition, nearly all antidepressants require 4–6 weeks to exert their therapeutic effects and their adverse effects cannot be ignored (Lavergne and Jay, 2010). Acupuncture is one of the complementary and alternative modalities for the treatment of various psychiatric and emotional disorders including Alzheimer disease, generalized anxiety disorder, posttraumatic stress disorder, sleep disorders, major depression, etc. (Aung et al., 2013; Wang et al., 2012). Experimental studies in humans have supported the idea that acupuncture is a safe and highly effective therapy in treating depression. A recent randomized controlled trial (RCT) used Patient Health Questionnaire to evaluate the effects of acupuncture and counseling on depression in 755 patients in primary care. Results indicated that both acupuncture and counseling significantly reduced depression at 3 months as compared to usual care alone (MacPherson et al., 2013). Another RCT showed that acupuncture combined with selective serotonin reuptake inhibitors (SSRIs) significantly improved the 17-item Hamilton Depression Rating Scale scores as compared to SSRIs alone over the 6-week period (Wang et al., 2014). However, the mechanisms of treatment with electroacupuncture (EA) on depression were not well understood. Neural plasticity, especially hippocampal synaptic plasticity, is thought to contribute to learning and memory (Foy, 2011). Impaired plasticity leads to cognitive deficits and memory loss. It is well known that learning ability decreased in depressive subjects. Pharmacological intervention that manipulates synaptic plasticity promotes the formation of memory. Zhang et al. (2012) reported that in corticosterone-stressed rats, hippocampal cell proliferation significantly decreased, and treatment with Lycium barbarum increased immobility time in forced swimming test (FST), restored the reduced spine density and the decreased levels of (postsynaptic density-95) PSD-95 in the hippocampus. It has also been reported (Luo et al., 2014) that chronic unpredictable mild stress model rats resulted in damaging the memory, impairing long-term potentiation (LTP), and downregulating PSD-95. The treatment with electroconvulsive shock under anesthesia improved memory possibly through reversing the excessive changes in hippocampal synaptic plasticity. LTP is considered as a cellular mechanism of memory formation and its induction required increased numbers of α-amino-3-hydroxy-5-methyl-4isoxazolepropionic acid receptors (AMPARs) and the activation of N-methyl-D-aspartate receptors (NMDARs) (Foy, 2011). In this study, a well-established model of depression, the putative genetic Wistar Kyoto (WKY) rat model of co-morbid depression and anxiety, was used (López-Rubalcava and Lucki, 2000; Rittenhouse et al., 2002), to investigate the effect
and mechanism of EA on depression. Behavioral studies including FST, OFT, and Morris water maze (MWM) test were used to evaluate depression-like behavior. Electrophysiological study was used to record LTP evoked at Schaffer collateral-CA1 synapses in the hippocampus, and western blot was used to measure the expression of hippocampal AMPAR and NMDAR subunits. It was hypothesized that treatment with EA will modulate the expression of hippocampus AMPAR and NMDAR, and LTP to improve depressionlike behavior.
2.
Results
2.1.
FST
The results of FST are shown in Fig. 1. Duration of immobility was significantly (Po0.01) longer in the blank controls (WKY rats, column 2) than in the normal controls (Wistar rats, column 1), indicating that WKY rats showed depression-like behavior. Interestingly, the duration of immobility was significantly (Po0.05) shorter in the EA group (95.11710.28 s) than in the blank control and sham EA groups (119.4979.12 s and 114.6377.07 s, respectively), suggesting that treatment with EA improves the depression-like behavior.
2.2.
OFT
The results of the OFT are shown in Fig. 2. The total distance (Fig. 2A), mean speed (Fig. 2B), and distance traveled within the central area (Fig. 2C) were significantly (Po0.01) shorter in the blank control (WKY rats) than in the normal control (Wistar rats). Duration of time spent by the rats in the central area was significantly (Po0.05) shorter in the blank control and sham EA than in the normal control (Fig. 2D). The number of rearing and grooming incidents is significantly (Po0.01) smaller in the blank control than in the normal control (Fig. 2E). These data indicate that WKY rats showed depression-like behavior. Although statistically significant differences were not found among the EA, blank control, and sham EA groups in any of these parameters, EA showed
Fig. 1 – Forced swimming test in rats after 3-week intervention. Data were expressed as mean7SEM. **Po0.01 compared to normal control; #Po0.05 compared to treatment with EA; ##Po0.01 compared to treatment with EA. EA, electroacupuncture; SEM, standard error of mean.
Please cite this article as: She, Y., et al., Possible antidepressant effects and mechanism of electroacupuncture in behaviors and hippocampal synaptic plasticity in a depression rat model. Brain Research (2015), http://dx.doi.org/10.1016/j. brainres.2015.10.033
247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306
BRES : 44522 brain research ] (]]]]) ]]]–]]]
307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366
3
Fig. 2 – Open field test in rats after 3-week intervention. Total distance (A), mean speed (B), central activity distance (C), duration of time spent by rats in the central area (D), and the number of rearing and grooming incidents (E) in the open field test. Data were expressed as mean7SEM. *Po0.05 compared to normal control; **Po0.01 compared to normal control. SEM, standard error of mean.
sham EA did not influence the learning ability. Although the duration was the same between EA and sham EA control during days 1–2, it became significantly (Po0.01) shorter in the EA group than in the sham EA control at day 5 (Fig. 3). These data demonstrate that treatment with EA improved the impaired learning ability in WKY rats.
2.4.
Fig. 3 – Escape latency of Morris water maze test in rats after 3-week intervention. Data were expressed as mean7SEM. ** Po0.01 compared to normal control; ##Po0.01 compared to treatment with EA. EA, electroacupuncture; SEM, standard error of mean.
an obvious tendency toward increased duration of time spent by rats in the central area.
2.3.
MWM test
The escape latency to find the target platform became gradually shorter in normal control Wistar rats, demonstrating that Wistar rats have normal learning ability during the MWM test (Fig. 3). The duration was significantly (Po0.01) longer in the blank and sham EA controls than in the normal control during days 1–5. This indicates that WKY rats showed a learning impairment and
Electrophysiological recording
The results of hippocampal Schaffer collateral-CA1 LTP Q2 induced by the 100 Hz tetanus for 1 s are shown in Fig. 4. The fEPSP slope was up to 136.0272.98% and 122.2872.58% in the normal control and EA groups, respectively. Tetanic stimulation failed to induce LTP in the blank control (107.2573.33%) and sham EA group (102.5772.35%).
2.5.
Western blot
The expression of GluN2B protein was significantly lower in the blank control and sham EA groups (Fig. 5). Treatment with EA restored the expression of GluN2B protein to levels observed in the normal control group. No differences were found in GluN1, GluN2A, GluR1, and GluR2 comparisons among all the groups.
3.
Discussion
The present study evaluated the antidepressive effects of EA therapy in the genetic WKY rat model of depression. The
Please cite this article as: She, Y., et al., Possible antidepressant effects and mechanism of electroacupuncture in behaviors and hippocampal synaptic plasticity in a depression rat model. Brain Research (2015), http://dx.doi.org/10.1016/j. brainres.2015.10.033
367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426
BRES : 44522
4
427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486
brain research ] (]]]]) ]]]–]]]
Fig. 4 – Induction of LTP in the hippocampal Schaffer collateral-CA1 in rats after 3-week intervention. fEPSP slopes were plotted as a percentage of baseline (A). The fEPSP slope of the preceding 10 min (duration 80–90 min) was averaged (B). Data were expressed as mean7SEM. **Po0.01 compared to the normal control; ##Po0.01 compared to treatment with EA. EA, electroacupuncture; fEPSP, field excitatory postsynaptic potential; LTP, long-term potentiation; SEM, standard error of mean.
Fig. 5 – Expression of hippocampal AMPAR and NMDAR subunits protein in rats after 3-week intervention. Western blot bands of expression of GluR1, GluR2, GluN1, GluN2A, GluN2B, and GAPDH protein. AMPAR, α-amino-3-hydroxy-5methyl-4-isoxazolepropionic acid receptor; GAPDH, Glyceraldehyde 3-phosphate dehydrogenase; NMDAR, Nmethyl-D-aspartate receptor.
results showed that 3-week EA intervention significantly increased the immobility time in FST as compared to the sham EA control. EA showed a obvious tendency to increase the duration spent by rats in the central area of an open field, although it did not show any effects on total distance, mean speed, central activity distance, and the number of rearing and grooming. These data demonstrated that treatment with EA improved depression-like behavior in WKY depression rat model. These results were in agreement with a previous study (Xu et al., 2011) using unpredictable chronic mild stress (UCMS)-induced depression rat model, in which treatment
with EA increased the consumption of sucrose and the number of crossing and rearing in OFT, indicating improvements in depression-like behaviors. It is noted that EA did not significantly improve the number of rearing and the locomotion activity in the WKY model as opposed to the UCMS model. This suggests that EA may produce differential effects in different models. Previous studies also demonstrated that EA improved neuropathic pain-induced depression-like behavior (Li et al., 2014). These studies in animal models support the clinical data that acupuncture is promising for the treatment of depression (Bosch et al., 2015). The present study also demonstrated that WKY rat model showed significant learning deficits and EA significantly enhanced the learning ability. In addition, treatment with EA improved the learning ability in UCMS-induced depression model (Bao et al., 2014). This intervention ameliorated ethanol-induced impairments of spatial learning and memory (Lu et al., 2014). However, the mechanisms of EA on learning ability are not understood. In recent years, converging evidence have shown that antidepressants and antidepressive therapies modulate hippocampus synaptic plasticity to improve memory (Paizanis et al., 2007; Pompili et al., 2013). LTP and long-term depression are two forms of synaptic plasticity and LTP is considered the cellular mechanism that underlies learning and memory. Exposure to acute and chronic stress was proven to impair hippocampal LTP, resulting in working memory impairment in animal studies (Bhagya et al., 2011; Dale et al., 2014; Quan et al., 2011; Shakesby et al., 2002). For example, vortioxetine (a 5-HT receptor antagonist) prevented the 5-HT-induced increase in the inhibitory postsynaptic potentials recorded from CA1 pyramidal cells, and enhanced theta burst LTP in hippocampal slices, and showed positive effects against cognitive dysfunction in major depression disorder model of rodents. To further explore the underlying mechanisms of treatment with EA on learning and memory, hippocampal Schaffer collateral-CA1 LTP was induced by the 100Hz tetanus in vitro. These data showed that treatment with EA significantly increased the slope of fEPSP as compared to the sham EA control. These suggest that EA may improve spatial
Please cite this article as: She, Y., et al., Possible antidepressant effects and mechanism of electroacupuncture in behaviors and hippocampal synaptic plasticity in a depression rat model. Brain Research (2015), http://dx.doi.org/10.1016/j. brainres.2015.10.033
487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546
BRES : 44522 brain research ] (]]]]) ]]]–]]]
547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606
learning and memory ability by enhancing the hippocampal LTP. The manner in which EA enhances LTP in the hippocampus warrants further investigation. Previous studies suggest that EA intervention may modulate Q3 hippocampal galanin (Modi et al., 2014) and dopamine (Dupin et al., 2006) to alleviate depression. Both AMPARs and NMDARs are involved in synaptic plasticity of LTP and Long term depression (LTD). AMPARs and NMDARs were further detected to determine the particular receptor subunits that might be related to the modulation of EA of hippocampal CA1 LTP in depressive rats. These results showed that the expression of GluN2B was increased after EA intervention. Accumulating evidences suggest that the enhancement of GluN2B subunits plays a critical role in the improvement of LTP in the CA1 region as well as learning and memory performance (Burgdorf et al., 2013; Shipton and Paulsen, 2014; Tang et al., 2001; Yilmaz et al., 2011). For instance (Yilmaz et al., 2011), venlafaxine and serotonin–norepinephrine reuptake inhibitor, improved depressionlike behaviors, and the depression reduced the expression of GluN2B in the hippocampus. Further, GLYX-13, a novel NMDAR glycine-site functional partial agonist, produced striking antidepressant effects accompanied by an enhancement in the magnitude of LTP at Schaffer collateral-CA1 synapses in vitro, and an increase in GluN2B in cell membrane (Burgdorf et al., 2013). Upregulation of GluN2B in CA1 pyramidal neurons results in an LTP enhancement (Müller et al., 2013) Together, these data suggest that treatment with EA may increase the expression of GluN2B to promote LTP and alleviate depression-like behavior. Additionally, this study did not find any difference in GluN1, GluN2A, GluR1, and GluR2 in the WKY rat model and EA-treated rats. In contrast, Martisova et al. (2012) reported that GluN1 and GluN2A were upregulated in an early-life stressed (maternal separation) rats; the expression of GluN2B, GluR1, and GluR2/3 were not changed in this model. Venlafaxine successfully reversed the increased expression of GluN1 and GluN2A. The difference in GluN1, GluN2a, and Glu2B between the present and the previous studies may be accounted for by the distinctive models. The relative small number of rats in each group may cause some bias of behavioral tests. In summary, these results demonstrate that treatment with EA significantly improved depression-like behavior in WKY depression rat model. This effect may be related to the increased NMDAR subunit expression of GluN2B and the enhanced LTP in the hippocampus.
4.
Experimental procedure
4.1.
Animals
Four-week-old male WKY and Wistar rats were obtained from Vital River Laboratory Animal Technology Company (Beijing, China). WKY rats showed a series of depressive symptoms that mimic those in humans such as exaggerated immobility in the FST, low level of social activities, decreased hippocampal volume as well as elevated rapid eye movement sleep in comparison to their Wistar control rats (DaSilva et al., 2011; Paré, 1989; Tizabi et al., 2010). The rats were kept under standard conditions (2272 1C, relative humidity 50–60%, alternate dark-
5
light cycles with light on at 8:00 am, food and tap water were available ad libitum). All rats were adapted to the environment for 1 week before the experiment. All procedures were performed according to the Suggestions for the Care and Use of Laboratory Animals formulated by the Ministry of Science and Technology of People's Republic of China and approved by the Animal Ethics Committee at Shanghai Municipal Hospital of Traditional Chinese Medicine, Shanghai, China.
4.2.
Experimental design
Male WKY rats were randomly categorized into three groups: EA group (n ¼7), sham EA group (n¼ 6), and blank control group (n¼ 6). The Wistar rats (n¼ 7), as an outbred albino rat strain from WKY, were used as normal control in this study. Rats in the EA group received 21 days of treatment with EA as reported (Lao et al., 2004; Xu et al., 2011) earlier: each rat was placed under an inverted clear 5″ 8″ 11″ plastic chamber without any restriction or anesthetic, disposable, sterile, and stainless steel acupuncture needles (diameter, 0.25 mm; length 25 mm; Suzhou Medical Appliance Factory, Suzhou, China) were inserted at Baihui (GV20) and Yintang (EX-HN3) at a depth of approximately 0.5 mm. An electrostimulator, Huatuo's Acupoint Nerve Stimulator (SDZ-V; Huatuo Medical Technology Co., Ltd. Suzhou, China), was connected, and electrical current was delivered to the needles. The anode was inserted into EX-HN3 and the cathode was inserted into GV20. The frequency of EA was held constant at 2 Hz (2 pulses/s) and pulse width was 0.2 ms. The intensity was started from 0.1 mA and adjusted to 3 mA, resulting in a manifestation of gentle head nodding, which is tolerated by rats. The needles were retained for 15 min. Sham EA group received no electrical stimulation: the needles were pasted at the surface of GV20 and EX-HN3 to make the needles touch the skin but not insert the acupoints. Normal control and blank control groups were not given any treatment.
4.3.
Behavioral tests
After completing the treatment on day 21, the rats were evaluated in the behavioral tests of FST, OFT, and MWM.
4.4.
FST
Briefly, in FST test (Kitada et al., 1981), rats were individually placed into glass cylinders (30 cm diameter 40 cm height) filled with water (23–25 1C) to a depth of 30 cm so that the rats could not touch the bottom of the cylinder with their hind limbs. Water was changed in between rats. On day 1, rats were placed in the water-filled cylinder for 5 min. It was pretested and was not recorded. After 24 h, rats were placed into water again for a 5-min test. The test session was videotaped and the time of immobility was measured.
4.5.
OFT
The OFT apparatus (Gray et al., 1975) was a square black box (50 cm 50 cm 100 cm) and was placed in dim light. The rat was placed in the box to move freely for 5 min, and all
Please cite this article as: She, Y., et al., Possible antidepressant effects and mechanism of electroacupuncture in behaviors and hippocampal synaptic plasticity in a depression rat model. Brain Research (2015), http://dx.doi.org/10.1016/j. brainres.2015.10.033
607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666
BRES : 44522
6
667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726
brain research ] (]]]]) ]]]–]]]
activities were recorded using a video camera mounted above the open field and recored in real time. Total distance, mean speed, time and distance in central area, and incidents of rearing and grooming were analyzed using the motion tracking system.
4.6.
MWM test
The ability of spatial learning and memory was evaluated using the MWM (Morris, 1984). The maze was a circular pool filled with water (22–25 1C) and divided into four equal quadrants. A circular platform was located 2 cm below the water surface on a fixed location. Rats were given four trials a day for five consecutive days. Once a rat climbed onto the platform and remained on it for 10 s, the trial was terminated. If the rat failed to reach the platform within 90 s, it was gently guided to the platform and allowed to stay on it for 10 s. The escape latency and distance traveled were recorded using a video tracking system. In probe test, on day 5, the hidden platform was removed and the rat was allowed to explore the pool for 90 s. The platform crossing frequencies in the target quadrant were measured.
4.7.
Electrophysiological recording
After the behavioral tests, rats were anesthetized using sodium pentobarbital and decapitated. The brain was removed immediately and placed in 0–4 1C oxygenated artificial cerebrospinal fluid (ACSF) containing 121 mM NaCl, 2.3 mM KCl, 0.5 mM CaCl2, 1.3 mM MgSO4, 1.0 mM NaH2PO4, 26.2 mM NaHCO3, and 11 mM D-glucose. Hippocampus was rapidly removed and both the hemispheres were dissected on ice; one side was placed in liquid nitrogen for the detection of protein and the other side was used for electrophysiological recording. Transverse hippocampal slices (400 mm) were cut using a vibratome in ice-cold cutting solution. Slices were transferred to a incubating chamber filled with ACSF containing 119 mM NaCl, 2.3 mM KCl, 2.5 mM CaCl2, 1.3 mM MgSO4, 1.0 mM NaH2PO4, 26.2 mM NaHCO3, and 11 mM D-glucose, and incubated for 1 h at 31 1C before recording. ACSF was perfused with 95% O2 and 5% CO2 continuously. A bipolar tungsten stimulating electrode was placed in the stratum radiatum of CA1 and the field excitatory postsynaptic potentials (fEPSPs) were recorded using a glass microelectrode filled with 0.5 M natrium aceticum (4–8 MΩ). Test stimuli were delivered every 15 s. After recording a stable baseline for 30 min, LTP was induced by a tetanic stimuli at 100 Hz for 1 s. fEPSP continued to be recorded for 60 min after highfrequency stimulation was administered. Data were recorded recorded using a Multiclamp 700B amplifier and digitized with a Digidata 1322 A (Axon Instruments, Foster City, CA).
4.8.
Western blot
Tissues were homogenized in an extraction buffer containing 2 sodium dodecyl sulfate (SDS), protease inhibitor mixture, and phosphatase inhibitor mixture. The homogenates were centrifuged at 13,000 rpm for 15 min at 4 1C. The same amount of total proteins was loaded on the gels, separated on 10% SDSpolyacrylamide gel electrophoresis, and transferred onto poly
(vinylidene fluoride) membranes. Blots were blocked in blocking buffer [1 Tris-buffered saline (TBS), 0.1% Tween-20 with 5% nonfat dry milk) for 1 h at room temperature. After washing, blots were incubated overnight at 4 1C with primary antibodies against GluR1 (1:5000; Millipore, Billerica, MA,USA), GluR2 (1:1000; Epitomics, Burlingame, CA), NMDAR (GluN1, 1:1000; Millipore,Billerica,MA,USA), NMDAR (GluN2A, 1:1500; Millipore, Billerica, MA, USA), and NMDAR (GluN2B, 1:1500; Millipore, Billerica, MA, USA). After washing twice in TBS-Tween 20 (TBS-T) and thrice in 1% milk TBS-T for 5 min each, blots were incubated with goat anti-mouse or anti-rabbit secondary antibody for 1 h at room temperature. Band intensity was detected using LI-COR Odyssey Infrared Fluorescence Scanning Imaging System(LI-COR, Lincoln, NE,USA).
4.9.
Statistical analysis
Data were analyzed using SPSS16.0 for Windows 7. All data were expressed as mean7standarddeviation. Comparisons between different groups were performed using one-way analysis of variance, followed by least significant difference test for post-hoc analyses. Pr 0.05 was considered statistically significant.
r e f e r e n c e s
Aung, S.K., Fay, H., Rd, H.R., 2013. Traditional Chinese medicine as a basis for treating psychiatric disorders: a review of theory with illustrative cases. Med. Acupunct. 25, 398–406. Bao, W., Jiao, S., Lu, J., Tu, Y., Song, Y., Wu, Q., 2014. Effect of electroacupuncture intervention on learning-memory ability Q4 and injured hippocampal neurons in depression rats. Acupunct. Res. 39, 136–141. Bhagya, V., Srikumar, B., Raju, T., Rao, B.S., 2011. Chronic escitalopram treatment restores spatial learning, monoamine levels, and hippocampal long-term potentiation in an animal model of depression. Psychopharmacology 214, 477–494. Bosch, P., van den Noort, M., Staudte, H., Lim, S., 2015. Schizophrenia and depression: a systematic review of the effective- Q5 ness and the working mechanisms behind acupuncture. EXPLORE: J. Sci. Heal.11281–291 Bschor, T., Bauer, M., Adli, M., 2014. Chronic and treatment Q6 resistant depression. Dtsch. Arztebl. Int. 111, 766776 771-U28. Burgdorf, J., Zhang, X.-l, Nicholson, K.L., Balster, R.L., Leander, J. D., Stanton, P.K., Gross, A.L., Kroes, R.A., Moskal, J.R., 2013. GLYX-13, a NMDA receptor glycine-site functional partial agonist, induces antidepressant-like effects without ketamine-like side effects. Neuropsychopharmacology 38, 729–742. Dale, E., Zhang, H., Leiser, S.C., Xiao, Y., Lu, D., Yang, C.R., Plath, N., Sanchez, C., 2014. Vortioxetine disinhibits pyramidal cell function and enhances synaptic plasticity in the rat hippocampus. J. Psychopharmacol. 28, 891–902. DaSilva, J., Husain, E., Lei, Y., Mann, G., Tejani-Butt, S., Morrison, A., 2011. Social partnering significantly reduced rapid eye movement sleep fragmentation in fear-conditioned, stresssensitive Wistar-Kyoto rats. Neuroscience 199, 193–204. Dupin, N., Mailliet, F., Rocher, C., Kessal, K., Spedding, M., Jay, T. M., 2006. Common efficacy of psychotropic drugs in restoring stress-induced impairment of prefrontal plasticity. Neurotox. Res. 10, 193–198. Foy, M.R., 2011. Ovarian hormones, aging and stress on hippocampal synaptic plasticity. Neurobiol. Learn. Mem. 95, 134–144.
Please cite this article as: She, Y., et al., Possible antidepressant effects and mechanism of electroacupuncture in behaviors and hippocampal synaptic plasticity in a depression rat model. Brain Research (2015), http://dx.doi.org/10.1016/j. brainres.2015.10.033
727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786
BRES : 44522 brain research ] (]]]]) ]]]–]]]
787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833
Gray, J.A., Drewett, R.F., Lalljee, B., 1975. Effects of neonatal castration and testosterone injection on adult open-field behaviour in rats with atypical sex difference in defecation. Anim. Behav. 23, 773–778. Kitada, Y., Miyauchi, T., Satoh, A., Satoh, S., 1981. Effects of antidepressants in the rat forced swimming test. Eur. J. Pharmacol. 72, 145–152. Lo´pez-Rubalcava, C., Lucki, I., 2000. Strain differences in the behavioral effects of antidepressant drugs in the rat forced swimming test. Neuropsychopharmacology 22, 191–199. Lao, L., Zhang, R.-X., Zhang, G., Wang, X., Berman, B.M., Ren, K., 2004. A parametric study of electroacupuncture on persistent hyperalgesia and Fos protein expression in rats. Brain Res. 1020, 18–29. Q7 Lavergne, F., Jay, T.M., 2010. A new strategy for antidepressant prescription. Front. Neurosci.4. Li, Q., Yue, N., Liu, S.-B., Wang, Z.-F., Mi, W.-L., Jiang, J.-W., Wu, G.C., Yu, J., Wang, Y.-Q., 2014. Effects of chronic electroacupuncture on depression-and anxiety-like behaviors in rats with chronic neuropathic pain. Evid.-Based Complement. Altern. Med.2014. Lu, B., Ma, Z., Cheng, F., Zhao, Y., Zhang, X., Mao, H., Shen, X., Liu, S., 2014. Effects of electroacupuncture on ethanol-induced impairments of spatial learning and memory and Fos expression in the hippocampus in rats. Neurosci. Lett. 576, 62–67. Luo, J., Min, S., Wei, K., Cao, J., Wang, B., Li, P., Dong, J., Liu, Y., 2014. Propofol prevents electroconvulsive-shock-induced memory impairment through regulation of hippocampal synaptic plasticity in a rat model of depression. Neuropsychiatr. Dis. Treat. 10, 1847. Mu¨ller, L., Tokay, T., Porath, K., Ko¨hling, R., Kirschstein, T., 2013. Enhanced NMDA receptor-dependent LTP in the epileptic CA1 area via upregulation of NR2B. Neurobiol. Dis. 54, 183–193. MacPherson, H., Richmond, S., Bland, M., Brealey, S., Gabe, R., Hopton, A., Keding, A., Lansdown, H., Perren, S., Sculpher, M., 2013. Acupuncture and counselling for depression in primary care: a randomised controlled trial. PLoS Med. 10, e1001518. Martisova, E., Solas, M., Horrillo, I., Ortega, J.E., Meana, J.J., Tordera, R.M., Ramı´rez, M.J., 2012. Long lasting effects of earlylife stress on glutamatergic/GABAergic circuitry in the rat hippocampus. Neuropharmacology 62, 1944–1953. Modi, K.K., Jana, A., Ghosh, S., Watson, R., Pahan, K., 2014. A physically-modified saline suppresses neuronal apoptosis, attenuates tau phosphorylation and protects memory in an animal model of Alzheimer’s disease. PLoS One 9, e103606. Morris, R., 1984. Developments of a water-maze procedure for studying spatial learning in the rat. J. Neurosci. Methods 11, 47–60. Paizanis, E., Hamon, M., Lanfumey, L., 2007. Hippocampal neurogenesis, depressive disorders, and antidepressant therapy. Neural Plast.2007.
7
Pare´, W.P., 1989. “Behavioral despair” test predicts stress ulcer in WKY rats. Physiol. Behav. 46, 483–487. Pompili, M., Serafini, G., Innamorati, M., Venturini, P., Fusar-Poli, P., Sher, L., Amore, M., Girardi, P., 2013. Agomelatine, a novel intriguing antidepressant option enhancing neuroplasticity: a critical review. World J. Biol. Psychiatry 14, 412–431. Quan, M.-N., Zhang, N., Wang, Y.-Y., Zhang, T., Yang, Z., 2011. Possible antidepressant effects and mechanisms of memantine in behaviors and synaptic plasticity of a depression rat model. Neuroscience 182, 88–97. Rittenhouse, P.A., Lo´pez-Rubalcava, C., Stanwood, G.D., Lucki, I., 2002. Amplified behavioral and endocrine responses to forced swim stress in the Wistar–Kyoto rat. Psychoneuroendocrinology 27, 303–318. Shakesby, A.C., Anwyl, R., Rowan, M.J., 2002. Overcoming the effects of stress on synaptic plasticity in the intact hippocampus: rapid actions of serotonergic and antidepressant agents. J. Neurosci. 22, 3638–3644. Shipton, O.A., Paulsen, O., 2014. GluN2A and GluN2B subunitcontaining NMDA receptors in hippocampal plasticity. Philos. Trans. R. Soc. Lond. B: Biol. Sci. 369, 20130163. Tang, Y.-P., Wang, H., Feng, R., Kyin, M., Tsien, J., 2001. Differential effects of enrichment on learning and memory function in NR2B transgenic mice. Neuropharmacology 41, 779–790. Tizabi, Y., Hauser, S.R., Tyler, K.Y., Getachew, B., Madani, R., Sharma, Y., Manaye, K.F., 2010. Effects of nicotine on depressive-like behavior and hippocampal volume of female WKY rats. Prog. Neuro-Psychopharmacol. Biol. Psychiatry 34, 62–69. Wang, T., Wang, L., Tao, W., Chen, L., 2014. Acupuncture combined with an antidepressant for patients with depression in hospital: a pragmatic randomised controlled trial. Acupunct. Med.32308–312acupmed-2013-010469 Wang, Z., Nie, B., Li, D., Zhao, Z., Han, Y., Song, H., Xu, J., Shan, B., Lu, J., Li, K., 2012. Effect of acupuncture in mild cognitive Q8 impairment and Alzheimer disease: a functional MRI studyPLos One7e42730 Xu, S., Li, S., Shen, X., Meng, X., Lao, L., 2011. Effects of electroacupuncture on depression in a rat model. Acupunct. Electrother. Res. 36, 259–273. Yilmaz, N., Demirdas, A., Yilmaz, M., Sutcu, R., Kirbas, A., Cure, M.C., Eren, I˙., 2011. Effects of venlafaxine and escitalopram treatments on NMDA receptors in the rat depression model. J. Membr. Biol. 242, 145–151. Zhang, E., Yau, S.Y., Lau, B.W.M., Ma, H., Lee, T., Chang, R.C.-C., So, K.F., 2012. Synaptic Plasticity, But Not Hippocampal Neurogenesis, Mediated the Counteractive Effect of Wolfberry on Depression in Rats1. Cell Transplant. 21, 2635–2649.
Please cite this article as: She, Y., et al., Possible antidepressant effects and mechanism of electroacupuncture in behaviors and hippocampal synaptic plasticity in a depression rat model. Brain Research (2015), http://dx.doi.org/10.1016/j. brainres.2015.10.033
834 835 836 837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876 877 878 879