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Activin increases dendritic spines in the adult hippocampal neurons
Abstracts
S221
PC12 cells by using total internal reflection fluorescent microscopy. We showed that overexpression of MyoII prolongs the duration of exocytosis and increases the total release of hormone. Interestingly, F-actin structure was dispersed soon after the stimulation in MyoII-overexpressed cells, while the structure was stable in unphosphorylatable form of MyoII (MyoII-DN)-overexpressed cells. We also found that MyoII immediately dispersed from the exocytotic sites, whereas MyoII-DN did not. These results suggest that MyoII controls the size of fusion pore via the actin cytoskeleton reorganization and the duration of exocytotic release.
activation due to delivery and lactation is involved in anxiety and depression-like behaviors.
doi:10.1016/j.neures.2009.09.1231
Dept Physiol, Yokohama City University Sch. Med., Yokohama, Japan
P3-e26 Activin increases dendritic spines in the adult hippocampal neurons Hideo Mukai, Yusuke Hatanaka, Tomokazu Tsurugizawa, Makoto Asashima, Suguru Kawato Dept Biophys and Life Sci, Grad Sch Arts and Sci, The Univ of Tokyo, Tokyo, Japan Activin, known as a mammalian reproductive hormone, is endogenously expressed in the hippocampus, independently of blood-derived activin. Rapid modulation of hippocampal synaptic plasticity by activin has not been well elucidated. We investigated the effect of activin A on dendritic spine morphology as well as synaptic transmission in adult male rat hippocampus. We are using a novel automatic analysis software of dendritic spines developped in our laboratory. The application of 10 ng/mL activin induced rapid modulation of the density and morphology of dendritic spines in CA1 pyramidal neurons within 2 h. The total spine density increased from 0.99 spines/m (control) to 1.20 spines/m (activin-treated). Co-presence of 100 ng/mL follistatin, an inhibitor of activin, completely abrogated the effect of activin. Blocking MAP kinase also prevented the activin-induced spinogenesis, however, inhibition of other class of kinases did not prevent the spinogenesis, thus suggesting spine remodeling by activin is mediated by Erk MAP kinase pathway. doi:10.1016/j.neures.2009.09.1232
P3-e27 Comparison of sex steroid synthesis between neonatal and adult rat hippocampus Shimpei Higo 1,2 , Toshihiro Kominami 1 , Yasushi Hojo 1 , Tetsuya Kimoto 1 , Suguru Kawato 1 1 2
Graduate School of Arts and Sciences, Univ of Tokyo, Tokyo, Japan; Research Fellow of the Japan Society for the Promotion of Science, Japan
Sex steroid synthesis in the hippocampus had been thought to be much more active at neonatal stage than at adult stage. However, the detailed comparison between these two stages had not been demonstrated yet. Here we performed the comparison about the mRNA level of steroidogenic enzymes and the rate of steroid metabolism between these two stages of the hippocampus. The relative expression level of P450(17 alpha), 17 beta- or 3 beta-hydroxysteroid dehydrogenase, or P450arom was approximately 1.3–1.5 fold higher in neonatal that at adult stage. The rate of sex steroid metabolism (from ehydroepiandrosterone to estradiol) was 2–7 fold(depending on different steps) more rapid in neonatal than at adult stage. Taken together, neonatal steroidogenesis is moderately more active than adult steroidogenesis. doi:10.1016/j.neures.2009.09.1233
P3-e28 Estrogen receptor ␣ is involved in anxiety- and depressivelike behaviors in postpartum rats after weaning pups Miyako Furuta 1,2 , Midori Ninomiya 2,3 , Shuichi Chiba 2 , Yu 2,3 3 Kajiyama , Shigenobu Shibata , Tatsuo Akema 1 , Hiroshi Kunugi 2,4 1
St. Marianna University, Japan; 2 Department of Mental Disorder Res., National Inst. of Neuroscience, National Center of Neurology and Psychiatry, Tokyo, Japan; 3 Department of Electrical Engineering and Bioscience, Waseda University, Tokyo, Japan; 4 CREST, JST, Japan
A drastic reduction in estrogen levels at delivery and lactation might be implicated in anxiety, depression, and postpartum psychosis. In the present study, primiparous rats at 3 weeks postpartum showed increased anxiety and depressive behaviors in elevated plus maze (EP), pre-pulse inhibition (PPI), and forced swimming (FS), tests, as compared to diestrus nulliparous females. An ER␣-selective agonist PPT (1.0 mg/kg) and E2 (0.25 mg/kg), which were subcutaneously injected once daily for 4 days, showed anxiolytic and antidepressant effects in EP and FS tests at 3 weeks postpartum. In contrast, an ER-selective agonist DPN (1.0 mg/kg) or DMSO did not have such effects. These results raise the possibility that a decrease in ER␣
doi:10.1016/j.neures.2009.09.1234
P3-e29 Dynamic changes in the AMPA receptor subunits compostion during the estrous cycle Toshiya Funabashi, Takuya Takahashi Electrical stimulation of the preoptic area (POA) elicited EPSCs in GnRH neurons in rats expressing EGFP under the control of the GnRH promoter (Kato and Sakuma), revealed by a whole cell voltage-clamp technique. Rectification index, defined as the ratio of the response at −60 mV to that at +40 mV, in female rats was significantly fluctuated during the estrous cycle and the highest on proestrus, suggesting that these synapses were lacking GluR2. AMPARs-mediated responses in proestrous rats were reduced by NASPM, an antagonist for GluR2-lacking AMPARs, compared with those in estrous rats. GluR1-ct, competing with GluR1 for synaptic delivery, was expressed in the POA of female rats using lentivirus. As the results, the LH surge was significantly attenuated. Finally, NASPM was injected into the POA in proestrous rats. As the result, the LH surge was significantly attenuated. These results suggests the presence of dynamic changes in the AMPA receptor subunits compostion during the estrous cycle and GluR2-lacking AMPARs are important to maintain surge of LH secretion in adults. doi:10.1016/j.neures.2009.09.1235
P3-e30 Visualization of secretory vesicles in the terminal nerve (TN)-gonadotropin releasing hormone (GnRH) neurons by single cell electroporation Hideki Abe, Takayuki Irie, Yoshitaka Oka Department of Biol. Sci., Grad. School of Sci., University of Tokyo, Tokyo, Japan The peptidergic neuron in the CNS release neuropeptides from widely branched neural processes. To understand the excitation-secretion coupling of peptidergic neurons, we recently established a primary culture system of fish TN-GnRH neurons, which grew both axon- and dendrite-like neurites on a flat substratum. Here, we applied our recently developed method for introducing exogenous molecules (e.g. fluorescent dyes and exogenous genes) to specified TN-GnRH neuron by single cell electroporation using conventional patch pipettes. We successfully introduced plasmids encoding various GFP variants to identified TN-GnRH neurons. Exogenous expressions of Synaptophysin-EGFP showed distributions of punctate fluorescence in the soma and neurites, which enabled the live-cell imaging of their movements. The single cell electroporation method applied to our isolated culture of TN-GnRH neurons will open up new possibilities for cellular studies of differential exocytosis of neuropeptides from various neuronal compartments. doi:10.1016/j.neures.2009.09.1236
P3-e31 Diurnal expression of neurosteroidogenic enzymes mRNA in the rat hippocampus Minoru Hattori, Eiji Munetsuna, Kento Takahashi, Kazunori Takekawa, Atsuhiko Ishida, Shogo Sakata, Takeshi Yamazaki Grad. School Integrated Arts Sci., Hiroshima Univ, Japan Neurosteroids are synthesized de novo from cholesterol in the central and peripheral nervous systems through mechanisms that are independent of peripheral steroidogenic organs. The adult rat hippocampus possesses the active neurosteroidogenic enzymes and proteins such as StAR and P450arom. It has been well established that steroid hormone such as cortisol secreted by adrenal glands undergoes a robust daily oscillation. Both pathways of adrenal steroidogenesis and hippocampal neurogenesis are quite similar. Nevertheless, the diurnal expression of neurosteroidogenic enzymes has not been clarified. Thus, we investigated diurnal expression of neurosteroidogenic enzymes and transcription factor mRNA using real-time RT-PCR. Diurnal expression of mRNA encoding StAR, 3-HSD, P450reductase was observed. These mRNAs were increased at the beginning of light period. The other mRNA levels were not changed. These data suggest that neurosteroidogenesis may undergo a daily oscillation similar to adrenal steroid hormone. doi:10.1016/j.neures.2009.09.1237
S221
PC12 cells by using total internal reflection fluorescent microscopy. We showed that overexpression of MyoII prolongs the duration of exocytosis and increases the total release of hormone. Interestingly, F-actin structure was dispersed soon after the stimulation in MyoII-overexpressed cells, while the structure was stable in unphosphorylatable form of MyoII (MyoII-DN)-overexpressed cells. We also found that MyoII immediately dispersed from the exocytotic sites, whereas MyoII-DN did not. These results suggest that MyoII controls the size of fusion pore via the actin cytoskeleton reorganization and the duration of exocytotic release.
activation due to delivery and lactation is involved in anxiety and depression-like behaviors.
doi:10.1016/j.neures.2009.09.1231
Dept Physiol, Yokohama City University Sch. Med., Yokohama, Japan
P3-e26 Activin increases dendritic spines in the adult hippocampal neurons Hideo Mukai, Yusuke Hatanaka, Tomokazu Tsurugizawa, Makoto Asashima, Suguru Kawato Dept Biophys and Life Sci, Grad Sch Arts and Sci, The Univ of Tokyo, Tokyo, Japan Activin, known as a mammalian reproductive hormone, is endogenously expressed in the hippocampus, independently of blood-derived activin. Rapid modulation of hippocampal synaptic plasticity by activin has not been well elucidated. We investigated the effect of activin A on dendritic spine morphology as well as synaptic transmission in adult male rat hippocampus. We are using a novel automatic analysis software of dendritic spines developped in our laboratory. The application of 10 ng/mL activin induced rapid modulation of the density and morphology of dendritic spines in CA1 pyramidal neurons within 2 h. The total spine density increased from 0.99 spines/m (control) to 1.20 spines/m (activin-treated). Co-presence of 100 ng/mL follistatin, an inhibitor of activin, completely abrogated the effect of activin. Blocking MAP kinase also prevented the activin-induced spinogenesis, however, inhibition of other class of kinases did not prevent the spinogenesis, thus suggesting spine remodeling by activin is mediated by Erk MAP kinase pathway. doi:10.1016/j.neures.2009.09.1232
P3-e27 Comparison of sex steroid synthesis between neonatal and adult rat hippocampus Shimpei Higo 1,2 , Toshihiro Kominami 1 , Yasushi Hojo 1 , Tetsuya Kimoto 1 , Suguru Kawato 1 1 2
Graduate School of Arts and Sciences, Univ of Tokyo, Tokyo, Japan; Research Fellow of the Japan Society for the Promotion of Science, Japan
Sex steroid synthesis in the hippocampus had been thought to be much more active at neonatal stage than at adult stage. However, the detailed comparison between these two stages had not been demonstrated yet. Here we performed the comparison about the mRNA level of steroidogenic enzymes and the rate of steroid metabolism between these two stages of the hippocampus. The relative expression level of P450(17 alpha), 17 beta- or 3 beta-hydroxysteroid dehydrogenase, or P450arom was approximately 1.3–1.5 fold higher in neonatal that at adult stage. The rate of sex steroid metabolism (from ehydroepiandrosterone to estradiol) was 2–7 fold(depending on different steps) more rapid in neonatal than at adult stage. Taken together, neonatal steroidogenesis is moderately more active than adult steroidogenesis. doi:10.1016/j.neures.2009.09.1233
P3-e28 Estrogen receptor ␣ is involved in anxiety- and depressivelike behaviors in postpartum rats after weaning pups Miyako Furuta 1,2 , Midori Ninomiya 2,3 , Shuichi Chiba 2 , Yu 2,3 3 Kajiyama , Shigenobu Shibata , Tatsuo Akema 1 , Hiroshi Kunugi 2,4 1
St. Marianna University, Japan; 2 Department of Mental Disorder Res., National Inst. of Neuroscience, National Center of Neurology and Psychiatry, Tokyo, Japan; 3 Department of Electrical Engineering and Bioscience, Waseda University, Tokyo, Japan; 4 CREST, JST, Japan
A drastic reduction in estrogen levels at delivery and lactation might be implicated in anxiety, depression, and postpartum psychosis. In the present study, primiparous rats at 3 weeks postpartum showed increased anxiety and depressive behaviors in elevated plus maze (EP), pre-pulse inhibition (PPI), and forced swimming (FS), tests, as compared to diestrus nulliparous females. An ER␣-selective agonist PPT (1.0 mg/kg) and E2 (0.25 mg/kg), which were subcutaneously injected once daily for 4 days, showed anxiolytic and antidepressant effects in EP and FS tests at 3 weeks postpartum. In contrast, an ER-selective agonist DPN (1.0 mg/kg) or DMSO did not have such effects. These results raise the possibility that a decrease in ER␣
doi:10.1016/j.neures.2009.09.1234
P3-e29 Dynamic changes in the AMPA receptor subunits compostion during the estrous cycle Toshiya Funabashi, Takuya Takahashi Electrical stimulation of the preoptic area (POA) elicited EPSCs in GnRH neurons in rats expressing EGFP under the control of the GnRH promoter (Kato and Sakuma), revealed by a whole cell voltage-clamp technique. Rectification index, defined as the ratio of the response at −60 mV to that at +40 mV, in female rats was significantly fluctuated during the estrous cycle and the highest on proestrus, suggesting that these synapses were lacking GluR2. AMPARs-mediated responses in proestrous rats were reduced by NASPM, an antagonist for GluR2-lacking AMPARs, compared with those in estrous rats. GluR1-ct, competing with GluR1 for synaptic delivery, was expressed in the POA of female rats using lentivirus. As the results, the LH surge was significantly attenuated. Finally, NASPM was injected into the POA in proestrous rats. As the result, the LH surge was significantly attenuated. These results suggests the presence of dynamic changes in the AMPA receptor subunits compostion during the estrous cycle and GluR2-lacking AMPARs are important to maintain surge of LH secretion in adults. doi:10.1016/j.neures.2009.09.1235
P3-e30 Visualization of secretory vesicles in the terminal nerve (TN)-gonadotropin releasing hormone (GnRH) neurons by single cell electroporation Hideki Abe, Takayuki Irie, Yoshitaka Oka Department of Biol. Sci., Grad. School of Sci., University of Tokyo, Tokyo, Japan The peptidergic neuron in the CNS release neuropeptides from widely branched neural processes. To understand the excitation-secretion coupling of peptidergic neurons, we recently established a primary culture system of fish TN-GnRH neurons, which grew both axon- and dendrite-like neurites on a flat substratum. Here, we applied our recently developed method for introducing exogenous molecules (e.g. fluorescent dyes and exogenous genes) to specified TN-GnRH neuron by single cell electroporation using conventional patch pipettes. We successfully introduced plasmids encoding various GFP variants to identified TN-GnRH neurons. Exogenous expressions of Synaptophysin-EGFP showed distributions of punctate fluorescence in the soma and neurites, which enabled the live-cell imaging of their movements. The single cell electroporation method applied to our isolated culture of TN-GnRH neurons will open up new possibilities for cellular studies of differential exocytosis of neuropeptides from various neuronal compartments. doi:10.1016/j.neures.2009.09.1236
P3-e31 Diurnal expression of neurosteroidogenic enzymes mRNA in the rat hippocampus Minoru Hattori, Eiji Munetsuna, Kento Takahashi, Kazunori Takekawa, Atsuhiko Ishida, Shogo Sakata, Takeshi Yamazaki Grad. School Integrated Arts Sci., Hiroshima Univ, Japan Neurosteroids are synthesized de novo from cholesterol in the central and peripheral nervous systems through mechanisms that are independent of peripheral steroidogenic organs. The adult rat hippocampus possesses the active neurosteroidogenic enzymes and proteins such as StAR and P450arom. It has been well established that steroid hormone such as cortisol secreted by adrenal glands undergoes a robust daily oscillation. Both pathways of adrenal steroidogenesis and hippocampal neurogenesis are quite similar. Nevertheless, the diurnal expression of neurosteroidogenic enzymes has not been clarified. Thus, we investigated diurnal expression of neurosteroidogenic enzymes and transcription factor mRNA using real-time RT-PCR. Diurnal expression of mRNA encoding StAR, 3-HSD, P450reductase was observed. These mRNAs were increased at the beginning of light period. The other mRNA levels were not changed. These data suggest that neurosteroidogenesis may undergo a daily oscillation similar to adrenal steroid hormone. doi:10.1016/j.neures.2009.09.1237