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Diversity in the presynaptic potentiation of excitatory neurotransmission from granule cells to molecular-layer interneurons in rat cerebellar cortex
Abstracts / Neuroscience Research 71S (2011) e108–e415
P3-a03 Diversity in the presynaptic potentiation of excitatory neurotransmission from granule cells to molecularlayer interneurons in rat cerebellar cortex Shin’Ichiro Satake 1,2 , Keiji Imoto 1,2 1
National Institute for Physiological Sciences (NIPS), Okazaki, Japan 2 The Graduate University for Advanced Studies (SOKENDAI), Okazaki, Japan
Previously, we reported that paired-pulse activation of granule cell (GC) axons causes a transient facilitation not only in the ratio of the peak amplitude but also that of the decay time constant of the EPSCs (PPRamp and PPRdecay , respectively) recorded from molecular-layer interneurons (INs). The mechanisms underlying the respective types of PPR facilitation were different. The facilitation of PPRamp was elicited by dual increase in the probability of vesicular release and in the multiplicity of the released vesicles. In contrast, the PPRdecay facilitation originated from extrasynaptic spillover of the GC glutamate and following their intersynaptic pooling. We here report that presynaptic potentiation of the GC-IN neurotransmission is classified into two distinct types by evaluation of the EPSC decay. Tetanic activation of GC axons (50 Hz for 200 ms) elicited a transient potentitation of the EPSC (namely, posttetanic potentiation; PTP) with a significant increase in the decay time constant. The PTP appeared to be presynaptically originated because the PPRamp value decreased during the potentiation, and was completely suppressed by GF109203X (1 M), a selective blocker of protein kinase C. The phorbol ester PDBu (0.5 M) presynaptically increased both the amplitude and the decay time of the EPSC. On the other hand, low-frequency activation of GCs (5 Hz for 20 s) caused a long-term potentiation (LTP) of the GC-IN EPSC with a decrease in the PPRamp depending on a protein kinase A-mediated mechanism; whereas, during the LTP, the EPSC decay remained unchanged. Furthermore, activation of adenylyl cyclase elicited presynaptic LTP without affecting the decay time of the GC-IN EPSC. These findings suggest that each of the distinct types of presynaptic potentitation, by reflecting the GC activation frequency during the induction, takes a unique part in processing neuronal information by differentially modifying the properties of multivesicular release at the single synapse. doi:10.1016/j.neures.2011.07.915
P3-a04 Regulation of hydrogen sulfide production and its cytoprotective effect in the retina Yoshinori Mikami 1 , Norihiro Shibuya 1 , Yuka Kimura 1 , Noriyuki Nagahara 2 , Masahiro Yamada 3 , Hideo Kimura 1 1
Dept. Mol. Pharmacol., Natl. Inst. Neurosci., NCNP., Tokyo, Japan 2 Dept. Environ. Med., Nippon Med. Sch., Tokyo, Japan 3 Neuroinformatics Lab., RIKEN BSI, Saitama, Japan
Hydrogen sulfide (H2 S) is a signaling molecule produced in many tissues. H2 S protects neurons from oxidative stress by increasing the levels of glutathione, a major intracellular antioxidant, through enhancing the activity of ␥-glutamylcysteine synthetase and the transport of cysteine and cystine. We recently demonstrated that 3-mercaptopyruvate sulfurtransferase (3MST) produces H2 S from 3-mercaptopyruvate, which is generated from cysteine and ␣-ketoglutarate (␣-KG) by cysteine aminotransferase (CAT) in the brain as well as in the vascular endothelium. However, the regulation of CAT and 3MST as well as the function of H2 S in the retina has not well been understood. Here we show that both 3MST and CAT were localized in the mouse retina. The retinal lysates produced H2 S in the presence of cysteine and ␣-KG. In the absence of ␣-KG, the lysates produced little H2 S. These observations indicate that H2 S is produced mainly by 3MST along with CAT in the retina. We will show the regulator of H2 S production and its physiological roles in vivo. doi:10.1016/j.neures.2011.07.916
P3-a05 P2X-purinoceptor-coupled cation channelmediated choline transport in cholinergic neurons Makoto Kaneda 1 Hiroyoshi Inoue 3
, Yasuhide Shigematsu 2 , Yukio Shimoda 2 ,
1
Dept. of Physiol., Keio Univ. Sch. Med., Tokyo, Japan 2 MRI, Tokyo Womens’ Medical Univ. 3 Dept. of Chemistry, Keio Univ. Sch. Med., Tokyo, Japan
Previous reports show that ion channels of P2X2-purinoceptors have a permeability to large cations. In the present study, we examined whether choline can permeate the ion channels of P2X2-purinoceptors in the cholinergic amacrine cells of the mouse retina. An application of ATP activated choline current in the OFF-cholinergic amacrine cells but not in the ON-cholinergic amacrine cells. Reversal potential of ATP-induced choline current shifted
e211
25 mV per 10 times change of extracellular choline concentration. Biophysiological and pharmacological characteristics of ATP-induced choline current well corresponded to those of P2X2-purinoceptor-mediated cation current. The immunoreactivity for choline transporter (high affinity) is stronger in the ON-cholinergic amacrine cells than in the OFF-cholinergic amacrine cells. An uptake of choline into cholinergic neuron was accelerated by ATP application. Our data raise a possibility that choline transport mechanism in cholinergic amacrine cells is different between ON- and OFF-pathway. Ion channels coupled with P2X2-purinoceptors work as an additional pathway of choline transport especially in the OFF-cholinergic amacrine cells of the mouse retina. Research fund: KAKENHI (21500373). doi:10.1016/j.neures.2011.07.917
P3-a06 Shingosine-1-phosphate regulates PKA/DARPP-32 signaling in striatal medium spiny neurons via GPR6independent mechanisms Ken Uematsu 1,2,3 Akinori Nishi 3
, Naohisa Uchimura 2 , Toyojiro Matsuishi 1 ,
1 Cognitive and Molecular Res. Inst. of Brain Diseases, Kurume Univ., Fukuoka, Japan 2 Dept. Neuropsychiatry, Kurume Univ. Sch. of Med., Fukuoka, Japan 3 Dept. Pharmacolgy, Kurume Univ. Sch. of Med., Fukuoka, Japan
Sphingosine-1-phosphate (S1P) is a bioactive sphingolipid metabolite that regulates critical cellular processes such as proliferation, survival and migration as well as angiogenesis, allergic responses and immune responses. S1P exerts its function by activating G protein-coupled receptors (GPCRs). Among GPCRs for S1P, GPR6 is selectively expressed in striatopallidal neurons in the striatum. It has been reported that GPR6 deficient mice show the reduced cyclic AMP levels in the striatum in vitro and the selective alterations in instrumental conditioning behaviors in vivo. In this study, we investigated the effect of S1P on cAMP/PKA signaling in mouse striatal slices by monitoring the phosphorylation states of an intracellular phosphoprotein, dopamine- and cAMP-regulated phosphoprotein of Mr 32 kDa (DARPP-32), in which Thr34 is phosphorylated by PKA. Treatment of slices with S1P (10 M) increased DARPP-32 Thr34 phosphorylation at 1 min of incubation by 3-fold. The increase in DARPP-32 phosphorylation was abolished by pretreatment with a dopamine D2 receptor agonist, quinpirole, or an adenosine A2A receptor antagonist, ZM241385. Analysis of the S1P effect in striatal slices from D1 -DARPP-32-Flag/D2 -DARPP-32-Myc transgenic mice revealed that S1P increased DARPP-32 Thr34 phosphorylation in D2 -type/striatopallidal neurons, but not in D1 -type/striatonigral neurons. We further examined the effect of S1P in striatal slices from GPR6 deficient mice. Interestingly, S1P increased DARPP-32 Thr34 phosphorylation at 1 min of incubation in GPR6 deficient mice, similarly to that in wild-type mice. These results demonstrate that S1P activates PKA/DARPP-32 signaling selectively in striatopallidal neurons, possibly by interacting with dopamine D2 and adenosine A2A receptors. However, the effect of S1P is not mediated through activation of GPR6, suggesting the involvement of other S1P receptors selectively functioning in striatopallidal neurons. doi:10.1016/j.neures.2011.07.918
P3-a07 Local acute serotonergic modulation on the excitability of single lateral amygdala Ryo Yamamoto , Tokio Sugai, Nobuo Kato Dep. of Physiol., Kanazawa Med. Univ., Uchinada, Japan The amygdala and serotonergic innervations thereunto are considered to cooperatively modulate the affective states and behaviors. In this study, we examined the effects of serotonin (5-HT) on the principal neurons in the lateral amygdala (LA) by whole-cell recording. In the current clamp mode, bath-application of 5-HT induced a depolarization of resting membrane potential about 5 mV. In voltage clamp mode, we checked the reversal potential of serotonin-induced current by applying voltage ramps from −50 mV to −130 mV, and that was nearby −105 mV. ␣-m-5-HT, a broad 5-HT2 receptor agonist, and WAY161503, a selective 5-HT2C receptor agonist, also induced similar current. With Ba2+ , the reversal potential of serotonin-induced current at −105 mV disappeared and a small inward current was observed in the voltage range from −50 mV to −130 mV. Thus, bath-application of 5-HT induced a depolarization of resting membrane potential in LA neurons by modulating Ba2+ sensitive potassium current. On the other hand, focal application of 5-HT to the soma of LA neuron elicited two types of outward current, instead of the inward current. One of the outward currents was picrotoxin sensitive. The other was induced activity dependently and not sensitive to
P3-a03 Diversity in the presynaptic potentiation of excitatory neurotransmission from granule cells to molecularlayer interneurons in rat cerebellar cortex Shin’Ichiro Satake 1,2 , Keiji Imoto 1,2 1
National Institute for Physiological Sciences (NIPS), Okazaki, Japan 2 The Graduate University for Advanced Studies (SOKENDAI), Okazaki, Japan
Previously, we reported that paired-pulse activation of granule cell (GC) axons causes a transient facilitation not only in the ratio of the peak amplitude but also that of the decay time constant of the EPSCs (PPRamp and PPRdecay , respectively) recorded from molecular-layer interneurons (INs). The mechanisms underlying the respective types of PPR facilitation were different. The facilitation of PPRamp was elicited by dual increase in the probability of vesicular release and in the multiplicity of the released vesicles. In contrast, the PPRdecay facilitation originated from extrasynaptic spillover of the GC glutamate and following their intersynaptic pooling. We here report that presynaptic potentiation of the GC-IN neurotransmission is classified into two distinct types by evaluation of the EPSC decay. Tetanic activation of GC axons (50 Hz for 200 ms) elicited a transient potentitation of the EPSC (namely, posttetanic potentiation; PTP) with a significant increase in the decay time constant. The PTP appeared to be presynaptically originated because the PPRamp value decreased during the potentiation, and was completely suppressed by GF109203X (1 M), a selective blocker of protein kinase C. The phorbol ester PDBu (0.5 M) presynaptically increased both the amplitude and the decay time of the EPSC. On the other hand, low-frequency activation of GCs (5 Hz for 20 s) caused a long-term potentiation (LTP) of the GC-IN EPSC with a decrease in the PPRamp depending on a protein kinase A-mediated mechanism; whereas, during the LTP, the EPSC decay remained unchanged. Furthermore, activation of adenylyl cyclase elicited presynaptic LTP without affecting the decay time of the GC-IN EPSC. These findings suggest that each of the distinct types of presynaptic potentitation, by reflecting the GC activation frequency during the induction, takes a unique part in processing neuronal information by differentially modifying the properties of multivesicular release at the single synapse. doi:10.1016/j.neures.2011.07.915
P3-a04 Regulation of hydrogen sulfide production and its cytoprotective effect in the retina Yoshinori Mikami 1 , Norihiro Shibuya 1 , Yuka Kimura 1 , Noriyuki Nagahara 2 , Masahiro Yamada 3 , Hideo Kimura 1 1
Dept. Mol. Pharmacol., Natl. Inst. Neurosci., NCNP., Tokyo, Japan 2 Dept. Environ. Med., Nippon Med. Sch., Tokyo, Japan 3 Neuroinformatics Lab., RIKEN BSI, Saitama, Japan
Hydrogen sulfide (H2 S) is a signaling molecule produced in many tissues. H2 S protects neurons from oxidative stress by increasing the levels of glutathione, a major intracellular antioxidant, through enhancing the activity of ␥-glutamylcysteine synthetase and the transport of cysteine and cystine. We recently demonstrated that 3-mercaptopyruvate sulfurtransferase (3MST) produces H2 S from 3-mercaptopyruvate, which is generated from cysteine and ␣-ketoglutarate (␣-KG) by cysteine aminotransferase (CAT) in the brain as well as in the vascular endothelium. However, the regulation of CAT and 3MST as well as the function of H2 S in the retina has not well been understood. Here we show that both 3MST and CAT were localized in the mouse retina. The retinal lysates produced H2 S in the presence of cysteine and ␣-KG. In the absence of ␣-KG, the lysates produced little H2 S. These observations indicate that H2 S is produced mainly by 3MST along with CAT in the retina. We will show the regulator of H2 S production and its physiological roles in vivo. doi:10.1016/j.neures.2011.07.916
P3-a05 P2X-purinoceptor-coupled cation channelmediated choline transport in cholinergic neurons Makoto Kaneda 1 Hiroyoshi Inoue 3
, Yasuhide Shigematsu 2 , Yukio Shimoda 2 ,
1
Dept. of Physiol., Keio Univ. Sch. Med., Tokyo, Japan 2 MRI, Tokyo Womens’ Medical Univ. 3 Dept. of Chemistry, Keio Univ. Sch. Med., Tokyo, Japan
Previous reports show that ion channels of P2X2-purinoceptors have a permeability to large cations. In the present study, we examined whether choline can permeate the ion channels of P2X2-purinoceptors in the cholinergic amacrine cells of the mouse retina. An application of ATP activated choline current in the OFF-cholinergic amacrine cells but not in the ON-cholinergic amacrine cells. Reversal potential of ATP-induced choline current shifted
e211
25 mV per 10 times change of extracellular choline concentration. Biophysiological and pharmacological characteristics of ATP-induced choline current well corresponded to those of P2X2-purinoceptor-mediated cation current. The immunoreactivity for choline transporter (high affinity) is stronger in the ON-cholinergic amacrine cells than in the OFF-cholinergic amacrine cells. An uptake of choline into cholinergic neuron was accelerated by ATP application. Our data raise a possibility that choline transport mechanism in cholinergic amacrine cells is different between ON- and OFF-pathway. Ion channels coupled with P2X2-purinoceptors work as an additional pathway of choline transport especially in the OFF-cholinergic amacrine cells of the mouse retina. Research fund: KAKENHI (21500373). doi:10.1016/j.neures.2011.07.917
P3-a06 Shingosine-1-phosphate regulates PKA/DARPP-32 signaling in striatal medium spiny neurons via GPR6independent mechanisms Ken Uematsu 1,2,3 Akinori Nishi 3
, Naohisa Uchimura 2 , Toyojiro Matsuishi 1 ,
1 Cognitive and Molecular Res. Inst. of Brain Diseases, Kurume Univ., Fukuoka, Japan 2 Dept. Neuropsychiatry, Kurume Univ. Sch. of Med., Fukuoka, Japan 3 Dept. Pharmacolgy, Kurume Univ. Sch. of Med., Fukuoka, Japan
Sphingosine-1-phosphate (S1P) is a bioactive sphingolipid metabolite that regulates critical cellular processes such as proliferation, survival and migration as well as angiogenesis, allergic responses and immune responses. S1P exerts its function by activating G protein-coupled receptors (GPCRs). Among GPCRs for S1P, GPR6 is selectively expressed in striatopallidal neurons in the striatum. It has been reported that GPR6 deficient mice show the reduced cyclic AMP levels in the striatum in vitro and the selective alterations in instrumental conditioning behaviors in vivo. In this study, we investigated the effect of S1P on cAMP/PKA signaling in mouse striatal slices by monitoring the phosphorylation states of an intracellular phosphoprotein, dopamine- and cAMP-regulated phosphoprotein of Mr 32 kDa (DARPP-32), in which Thr34 is phosphorylated by PKA. Treatment of slices with S1P (10 M) increased DARPP-32 Thr34 phosphorylation at 1 min of incubation by 3-fold. The increase in DARPP-32 phosphorylation was abolished by pretreatment with a dopamine D2 receptor agonist, quinpirole, or an adenosine A2A receptor antagonist, ZM241385. Analysis of the S1P effect in striatal slices from D1 -DARPP-32-Flag/D2 -DARPP-32-Myc transgenic mice revealed that S1P increased DARPP-32 Thr34 phosphorylation in D2 -type/striatopallidal neurons, but not in D1 -type/striatonigral neurons. We further examined the effect of S1P in striatal slices from GPR6 deficient mice. Interestingly, S1P increased DARPP-32 Thr34 phosphorylation at 1 min of incubation in GPR6 deficient mice, similarly to that in wild-type mice. These results demonstrate that S1P activates PKA/DARPP-32 signaling selectively in striatopallidal neurons, possibly by interacting with dopamine D2 and adenosine A2A receptors. However, the effect of S1P is not mediated through activation of GPR6, suggesting the involvement of other S1P receptors selectively functioning in striatopallidal neurons. doi:10.1016/j.neures.2011.07.918
P3-a07 Local acute serotonergic modulation on the excitability of single lateral amygdala Ryo Yamamoto , Tokio Sugai, Nobuo Kato Dep. of Physiol., Kanazawa Med. Univ., Uchinada, Japan The amygdala and serotonergic innervations thereunto are considered to cooperatively modulate the affective states and behaviors. In this study, we examined the effects of serotonin (5-HT) on the principal neurons in the lateral amygdala (LA) by whole-cell recording. In the current clamp mode, bath-application of 5-HT induced a depolarization of resting membrane potential about 5 mV. In voltage clamp mode, we checked the reversal potential of serotonin-induced current by applying voltage ramps from −50 mV to −130 mV, and that was nearby −105 mV. ␣-m-5-HT, a broad 5-HT2 receptor agonist, and WAY161503, a selective 5-HT2C receptor agonist, also induced similar current. With Ba2+ , the reversal potential of serotonin-induced current at −105 mV disappeared and a small inward current was observed in the voltage range from −50 mV to −130 mV. Thus, bath-application of 5-HT induced a depolarization of resting membrane potential in LA neurons by modulating Ba2+ sensitive potassium current. On the other hand, focal application of 5-HT to the soma of LA neuron elicited two types of outward current, instead of the inward current. One of the outward currents was picrotoxin sensitive. The other was induced activity dependently and not sensitive to