ポスター発表 (Poster Sessions)

成体ニューロン新生 Adult Neurogenesis
P2-1-89 クエチアピンは短期投与ではなく、長期投与でのみラット海馬神経新生を増加させる Quetiapine treatment increases rat hippocampal neurogenesis in chronic, but not acute administration ○鈴木陽子¹, 村田雄介¹, 森征慶¹, 美根和典¹ ○Yoko Suzuki¹, Yusuke Murata¹, Masayoshi Mori¹, Kazunori Mine¹ 福岡大学薬学部臨床心身治療学¹ Dept Psychosom Med, Fac Pharmaceuti Sci, Univ of Fukuoka, Fukuoka, Japan¹ [Introduction] Quetiapine has been used worldwide as the treatment for schizophrenia. Several reports suggested that quetiapine has also efficacy in the treatment of mood disorders. However, the mechanism of quetiapine's antidepressive effect remains currently unclear. Previous studies showed that most antidepressants can increase adult mammalian hippocampal neurogenesis in chronic, but not acute treatment, which could contribute to the therapeutic effect of antidepressants. It is possible that quetiapine may cause antidepressive action through affecting hippocampal neurogenesis positively. In the present study, we investigated the effect of acute, subchronic and chronic treatment of quetiapine on hippocampal neurogenesis of rat under nonstress conditions. [Methods] Male Sprague-Dawley rats (6 weeks old at arrival) were used. Quetiapine hemifumarate was dissolved in saline. After 1 week acclimatization, quetiapine was intraperitoneally given (10 mg/kg) daily for 1, 7 or 28 days. Rats were transcardially perfused with 4% paraformaldehyde one day after the last injection. Brains were removed and serial coronal sections at 40μm thickness were made using freezing microtome. For stereological quantification of newly generated neurons in dentate gyrus (DG) of hippocampus, the estimate of doublecortin (DCX)-immunoreactive cells using DAB staining was determined by optical fractionator procedure. [Results] The total estimates of DCX-positive cells in DG were significantly increased in 28 days treatment group compared to 1 or 7 days treatment group. No significant differences were observed in physiological (body weight gain, food consumption) and behavioural (novelty-suppressed feeding test) changes. [Discussion] Our findings suggested that hippocampal neurogenesis may be elevated by chronic, but not acute quetiapine treatment. In order to elucidate the exact mechanism underlying the increase in neurogenesis induced by quetiapine, further pharmacological study should be needed.	P2-1-90 リチウムは海馬歯状回ニューロン脱落後のニューロン新生を促進する Lithium promotes neuronal regeneration following neuronal degeneration in the hippocampal dentate gyrus ○米山雅紀¹, 梅田佳寿美¹, 長谷部茂¹, 荻田喜代一¹ ○Masanori Yoneyama¹, Kasumi Umeda¹, Shigeru Hasebe¹, Kiyokazu Ogita¹ 摂南大学　薬学部　薬理学¹ Dept Pharmacol, Fac. Pharm. Sci, Setsunan Univ. Osaka¹ Various neurological injuries are widely known to promote endogenous neurogenesis in the hippocampal dentate gyrus of adulthood. Our previous studies demonstrated that the granule cells in the hippocampal dentate gyrus are injured and disappeared on day 2 post treatment with trimethyltin chloride (TMT), with being regenerated in the dentate granule cell layer (GCL) after neuronal loss. To elucidate whether lithium has beneficial effect on neuronal regeneration after neuronal damage in the hippocampal dentate gyrus, we evaluated the effect of lithium carbonate on neurogenesis in the hippocampal dentate gyrus damaged by TMT. Either lithium carbonate (100 mg/kg) or vehicle was injected for 14 days every 24 h from day 2 after TMT treatment. To label mitotic cells, we gave mice a single series of 2 injections of BrdU every 12 h from day 2 after TMT treatment and then prepared hippocampal sagittal sections for determination of BrdU (newly generated cells marker), NeuN (mature neuronal cell marker), and doublecortin (DCX, immature neuronal cell marker) on day 30 after TMT treatment. In addition, locomotor activity and forced swimming tests were carried out on day 30 after TMT treatment. Immunostaining revealed that lithium markedly increased the number of BrdU/NueN- and BrdU/DCX-positive cells in the GCL and subgranular zone on day 30 after TMT treatment. However, lithium failed to affect the number of BrdU/NeuN- and BrdU/DCX-positive cells in animals treated with saline at any days. On day 30 after TMT treatment, lithium abolished TMT-induced prolongation of immobility time in the forced swimming test. These results suggest that lithium promotes neuronal regeneration after neuronal degeneration in the hippocampal dentate gyrus
P2-1-91 コヒーシン欠損による神経新生の抑制 Cohesin regulates neurogenesis in the adult subventricular zone ○藤田幸¹, 坂東優篤², 白髭克彦², 山下俊英¹ ○Yuki Fujita¹, Masashige Bando², Katsuhiko Shirahige², Toshihide Yamashita¹ 大阪大学大学院医学系研究科分子神経科学¹, 東京大学分子細胞生物学研究所エピゲノム疾患研究センター² Dept of Mol Neurosci, Grad Sch of Med, Osaka Univ, Osaka¹, Lab of Genome Structure and Function, Institute of Mol Cell Biosci, Univ of Tokyo, Tokyo² Cohesin complex is composed of four subunits, and has a role in sister chromatid cohesion, which is crucial for accurate chromosome segregation. These observations indicate that cohisin complex is essential for cell cycle progression and cellular proliferation. Here, we examined the consequences of removal of cohesin function within the subventricular zone of adult neural stem cell niche. We revealed that neurogenesis is inhibited when cohesin function is removed from subventricular zone stem cells. Inhibition of cohesin reduces the number of GFAP+ cells and DCX+ cells in subventricular zone. These results suggest that cohesin complex regulates adult neurogenesis in subventricular zone.	P2-1-92 ゼブラフィッシュ視蓋におけるバルプロ酸（HDAC阻害剤）の細胞増殖調節 HDAC inhibitor valproic acid regulates cell proliferation in the zebrafish optic tectum ○土澤美希¹, 河野宏光¹, 伊藤容子¹, 田中英臣¹, 大島登志男¹ ○Miki Dozawa¹, Hiromitsu Kono¹, Yoko Ito¹, Hideomi Tanaka¹, Toshio Ohshima¹ 早稲田大学大学院　先進理工学研究科　生命医科学専攻¹ Dept. of Life Sci. Med. Bio Sci., Sch. of Adv. Sci. Eng., Waseda Univ., Tokyo¹ Valproic acid (VPA) has been used as the therapeutic drug for epilepsy and bipolar disorder. Several reports demonstrated the effects of VPA, e.g.: inhibitions of GABA transaminase, folic acid metabolism, histone deacetylase (HDAC), and glycogen synthase kinase-3. VPA causes teratogenic changes in embryonic zebrafish brain, however, its effects on neural stem cells (NSCs) in the embryonic and adult zebrafish brains have not been studied. In this study, we found that VPA and HDAC inhibitor administration enhanced the number of proliferating cells in embryonic zebrafish hindbrain. We next analyzed the effect of VPA and HDAC inhibitor administration to proliferation of NSCs in the adult zebrafish optic tectum. In contrast to the embryonic hindbrain, we found that VPA and HDAC inhibitor administration reduced the number of proliferating cells in the adult zebrafish optic tectum, suggesting a possibility that VPA affects cell proliferation by HDAC inhibition and HDAC may affects the cell proliferation in embryonic hindbrain and adult optic tectum by different machinaries. Cell cycle progression was suppressed and the number of neuron was not changed in optic tectum of adult zebrafish brain by HDAC inhibition. Several studies demonstrate that HDAC inhibits Notch signaling pathway, and Notch signaling regulates proliferation of NSCs in the telencephalon of adult zebrafish. According to these studies, we addressed the effect of Notch inhibitor to the cell proliferation in adult zebrafish optic tectum. We found that treatment of Notch inhibitor increased the number of proliferating cells in the adult zebrafish optic tectum. Interestingly, HDAC inhibitor treatment upregulated the expression of her4 which is target of Notch signaling. These results suggest that HDAC inhibitor activates Notch signaling to regulate cell proliferation in optic tectum of adult zebrafish. Now we are analyzing the relationship between HDAC and Notch signaling in NSCs in the adult zebrafish brain.
P2-1-93 成体マウスの脳室周囲器官における神経幹/前駆細胞 Neural stem/progenitor cells in the circumventricular organs of adult mouse ○古部瑛莉子¹, 蓬莱敦¹, 宮田清司¹ ○Eriko Furube¹, Atsushi Hourai¹, Seiji Miyata¹ 京都工芸繊維大院・応用生物学¹ Dept of Appl Biol, Kyoto Inst of Technol, Kyoto, Japan¹ The circumventricular organs (CVOs) including the organum vasculosum of the lamina terminalis (OVLT), subfornical organ (SFO), median eminence (ME), and area postrema (AP) allow parenchyma cells to sense a blood-derived substances and/or secret peptides into blood circulation. In the present study, we demonstrate continuous neurogenesis in the CVOs of adult mice by employing immunohistochemistry of neuronal progenitor cell marker Math1 and Mash1, mitotic marker bromodeoxyuridine (BrdU) labeling and mature neuron marker HuC/D and MAP2. Mash1-positive cells were observed in the capillary plexus in the OVLT, the outer shell and ventromedial core in the SFO, the internal zone of the ME, and the lateral zone in the AP, moreover, incorporation of BrdU was seen within Mash1-positive cells. Math1-positive cells distributed at the capillary plexus in the OVLT, the outer shell and ventromedial core in the SFO, the internal zone in the ME, and the central zone of the AP, moreover, incorporation of BrdU was seen within Math1-positive cells. In addition, many number of Math1-positive cells were observed in the Arc, although Mash1-positive cells were a few. BrdU-labeled HuC/D- or MAP2-positive neurons distributed sparsely throughout the OVLT and AP, although Mash1 and Math1-positive neurons were present at discrete regions. On the other hand, there was no prominent difference of distributional pattern between Mash1-and Math1-positive cells and HuC/D-and MAP2-positive neurons in the SFO and ME.We revealed that most of Mash1- and Math1-positive NPCs express high level of plasminogen, whereas a subpopulation of HuC/D-and MAP2-positive neurons expressed low level. In conclusion, the present study demonstrates continuous neurogenesis occurs in the OVLT, SFO, AP and ME, and NPCs migrate only a short distance to integrate into neural circuit in the CVOs of adult rodents and furthermore plasminogen may be responsible for neurogenesis processes.	P2-1-94 成体海馬ニューロン新生に対するコリン作動性機構 The role of hippocampal cholinergic system on the maturation of adult born neurons ○松田孟士¹, , 久恒辰博¹ ○Takeshi Matsuda¹, Bruno Herculano¹, Tatsuhiro Hisatsune¹ 東京大院・新領域・先端生命¹ Dep. of Integrated Biosci., Grad. Sch. of Frontier Sciences, The Univ. of Tokyo, Kashiwa, Japan¹ Hippocampal neurogenesis in adult mice is enhanced by the improvement of daily habit, such as voluntary exercise or spatial learning. On this occasion, it has been argued that acetylcholine (ACh) release into hippocampal dentate gyrus from septal cholinergic neurons is increased. However, in the brain of an aged person and an Alzheimer's disease (AD) patient, it has been raised the possibility that the ACh secretion is reduced in the cholinergic neurons. Moreover, it had been shown that there is a significant correlation between adult hippocampal neurogenesis and memory function. In this study, in order to investigate the influence of cholinergic system on the maturation of new hippocampal neurons in AD, we examined the phenotype of new-born neurons in AD model double transgenic mice (B6C3-Tg(APPswe, PSEN1dE9)85Dbo/J) chronically treated with a cholinesterase inhibitor, rivastigmine (1 mg/kg/day, s.c. for 6 weeks). As a result of classifying the new-born neurons by the length of dendrites as a maturity indicator after doublecortin staining, it revealed that the maturation of adult-born neurons in the treatment group was superior to that in the control group. These results suggest that, in AD, the maturation of new-born neurons is inhibited by inadequate release of ACh and this inhibited maturation is ameliorated by cholinesterase inhibitor treatment.
P2-1-95 嗅球における神経新生を制御する分子機構の解析ーin vivoエレクトロポレーション法の応用 Identification of signaling pathways that regulate the postnatal olfactory neurogenesis by in vivo electroporation ○伊東秀記¹, 森下理香¹, 岩本郁子¹, 永田浩一¹ ○Hidenori Ito¹, Rika Morishita¹, Ikuko Iwamoto¹, Koh-ichi Nagata¹ 愛知県コロニー・研・神経制御¹ Dept Mol Neurobiol, Inst for Develop Res, AIchi Human Service Center¹ Active postnatal neurogenesis is found in the subventricular zone (SVZ) of the lateral ventricles. New neurons generated in SVZ migrate through the rostral migratory stream (RMS) to the olfactory bulb and then differentiate to granule cells and periglomerular cells. In this study, we attempted to identify the molecular basis of the postnatal olfactory neurogenesis by in vivo electroporation. GFP-expressing plasmid was injected into the lateral ventricles of neonatal mice (P0-P2) using a pulled glass capillary and then electric pulses were applied. After 4 to 7 days, we could observe significant amount of GFP-labeled cells in RMS and olfactory bulb. We electroporated knockdown vectors for various signaling molecules and found that the ablation of Rac resulted in the reduction of GFP-labeled cells in the olfactory bulb. Expression of the dominant negative form of Rac caused accumulation of neuroblast cells in SVZ/RMS. These results suggest that Rac plays a crucial role in the postnatal olfactory neurogenesis. We are now trying to reveal the function of Rac in migration and proliferation of neuroblasts in SVZ/RMS because this molecule is known to regulate these cell biological processes of other types of cells such as fibroblasts. We will also show possible activating factors and effector molecules for Rac that regulate the postnatal olfactory neurogenesis.	P2-1-96 遺伝子改変メダカを用いた孵化後の脳発達における神経前駆細胞の細胞系譜解析 Clonal analysis of neuronal progenitors in the post-hatch medaka Oryzias latipes) brain using transgenic lines ○磯江泰子¹, 奥山輝大^1,2, 保木昌仁¹, 末廣勇司^1,3, 山岸弦記¹, 成瀬清², 木下政人⁴, 亀井保博², 清水厚志^1,5, 久保健雄¹, 竹内秀明¹ ○Yasuko Isoe¹, Teruhiro Okuyama^1,2, Masahito Houki¹, Suehiro Yuji^1,3, Genki Yamagishi¹, Kiyoshi Naruse², Masato Kinoshita⁴, Yasuhiro Kamei², Atsushi Shimizu^1,5, Takeo Kubo¹, Hideaki Takeuchi¹ 東京大院・理・生物科学¹, 基礎生物学研究所², 東京女子医科大・生理学³, 京都大院・農・生命応用⁴, 慶應大・医・分子生物⁵ Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Tokyo, Japan¹, National Institute for Basic Biology, Myodaiji, Okazaki, Aichi, Japan², Department of Physiology, Tokyo Women's Medical University School of Medicine, Tokyo, Japan³, Division of Applied Biosciences, Graduate School of Agriculture, Kyoto University, Kyoto, Japan⁴, Department of Molecular Biology, Keio University School of Medicine, Tokyo, Japan⁵ In vertebrates, basic neural networks of the brain are defined during embryonic development. In contrast, brain growth spurt occurs postnatally, accompanied by the rapid increases in cell number and brain volume. It remains unknown, however, how postnatal (post-hatch) neurogenesis contributes to the organization of neural network required for social behaviors. To address this subject, we focused on medaka fish (Oryzias latipes), which is a model animal for molecular genetics and show prominent post-hatch brain growth and behavioral development. We intended to generate transgenic medaka fish, in which post-hatch neurogenesis can be genetically modified. In the previous meeting, we demonstrated that HuC promoter drives specifically in newborn neural progenitors in the adult brain using transgenic line (HuC:loxP-DsRed-loxP-GFP). Stochastic recombination induced by micro-injection of Cre mRNA into the Tg embryos at the 1 cell stage visualized clonally-related neurons which are clustered in compartmented regions in the telencephalon of the adult medaka brain. In the present meeting, we show that heat-shock induced the Cre-recombination in the nervous system in the transgenic embryo carrying the two constructs (HSP:Cre and HuC:loxP-DsRed-loxP-GFP). Interestingly, mosaic recombination patterns formed in the Tgs differed depending on the timing of the heat-shock during the developmental stages. In addition, we succeeded to visualize clonally-related HuC-expressing cells in the adult medaka fish by inducing heat-shock in a restricted larval brain area using an infrared laser-evoked gene operator (IR-LEGO) system.
P2-1-97 SSRI長期投与による海馬神経新生における5-HT4受容体の役割 The role of 5-HT4 receptor in hippocampal neurogenesis by chronic SSRI treatment ○瀬木-西田恵里¹, 吉良俊彦², 井本有基², 小林克典³ ○Eri Segi-Nishida¹, Toshihiko Kira², Yuki Imoto², Katsunori Kobayashi³ 京都大院・薬・システム創薬¹, 京都大院・薬・生体情報², 日本医大・薬理³ Dept. Syst. Biosci. for Drug Discov., Kyoto Univ. Pharm. Sci.¹, Dept. Physiol Chem., Kyoto Univ. Pharm. Sci.², Dept. Pharmacol., Nippon Med. Sch.³ Hippocampal neurogenesis is increased by chronic treatment of selective serotonin (5-hydroxytryptamine, 5-HT) reuptake inhibitors (SSRIs). SSRIs increase proliferation and differentiation of neural progenitors in the dentate gyrus (DG). Among 14 subtypes of 5-HT receptors, G_s-coupled receptors, such as 5-HT_{4, 5, 6, 7} receptors, in the postsynaptic cells have been postulated to be involved in the promotion of neurogenesis. Since 5-HT4 receptor is expressed at a high level in the DG and the treatment of 5-HT4 receptor agonist increases cell proliferation in the DG, we investigated whether 5-HT4 receptor is involved in the promotion of hippocampal neurogenesis by SSRI treatment by using 5-HT4 receptor deficient (5-HT4R KO) mice. 5-HT4R KO mice and wild-type (WT) mice were treated with fluoxetine as a SSRI at a dose of 22 mg/kg/day for 21 days. While the fluoxetine treatment significantly increased cell proliferation in the DG of WT mice, no significant change was observed between saline and the fluoxetine treatment in 5-HT4R KO mice. Doublecortin-immunoreactivities (DCX-IRs), as one of the markers for neurogenesis, in the DG were also increased in fluoxetine-treated WT mice compared with saline-treated WT mice. On the other hand, no changes were observed in DCX-IRs between saline and the fluoxetine treatment in 5-HT4R KO mice. We then examined whether 5-HT4 receptor regulates expression of genes related to hippocampal neurogenesis, such as brain-derived neurotrophic factor (BDNF), in the DG by the fluoxetine treatment. BDNF mRNA expression in the DG of WT mice was increased by the fluoxetine treatment, but not in that of 5-HT4R KO mice. These results suggest the involvement of 5-HT4 receptors in the increase of the hippocampal neurogenesis by the chronic SSRI treatment.	P2-1-98 成体海馬での神経前駆細胞の維持におけるDBIの役割 The involvement of diazepam binding inhibitor in the maintenance of neural progenitor cells in the adult dente gyrus ○金子順¹, 相澤憲¹, 岡田夏美¹, 木村康太¹, 久恒辰博¹ ○Jun Kaneko¹, Ken Aizawa¹, Natsumi Okada¹, Kohta Kimura¹, Tatsuhiro Hisatsune¹ 東京大学大学院　新領域創成科学研究科　先端生命科学専攻¹ Department of Integrated Biosciences, Graduate School of Frontier Sciences, The University of Tokyo¹ Newborn neurons are regenerating at the subgranular zone of the dentate gyrus throughout life; therefore, it has been argued the implication of long-term maintenance of neural progenitor cells. Previously we reported that the differentiation of neural progenitor cells was stimulated by GABAergic signal. Hippocampal neurogenesis is promoted via GABAergic signal which could be modulated by several endogenous molecules. Diazepam binding inhibitor (DBI; also known as ACBP; acyl-CoA Binding Peptide) is a multifunctional small cytosolic polypeptide (87 a.a.) and is expressed in neural progenitor cells. After secretion from producing cells, DBI and its fragment Octadecaneuropeptide proteolytic product (ODN) bind to GABA_A-receptor and inhibit Cl^- flow through the GABA_A-receptor. In this study, we performed a DBI knockdown experiment to investigate a functional role of DBI in dentate gyrus. In addition, to evaluate the effect of DBI knockdown for differentiation we used retrovirus to trace the progression of maturation of divided cells. We performed virus injections to dentate gyrus of wild type mice at 6 weeks old. A number of doublecortin (DCX; immature neuron marker) positive cells labeled with retrovirus significantly increased in DBI knockdown mice compared to control mice at 1 week postinjection. These data suggest DBI knock down in dentate gyrus promotes differentiation of divided cells into DCX positive immature neurons. One of the functions of DBI in neural progenitor cells appears to be suppression of differentiation via inhibition of GABA_A-receptor. As a result of DBI knockdown, GABA signal is enhanced relatively and the differentiation of neural progenitor cells is promoted.
P2-1-99 海馬新生ニューロンの前シナプス終末特異的な神経伝達機能阻害マウスの空間記憶機能 Affected memory function in transgenic mice with the attenuated presynaptic neurotransmission of hippocampal adult-born neurons ○浅井裕貴¹, , 阿部欣史¹, 金子順¹, 今吉格^3,4,5, 影山龍一郎⁴, 久恒辰博¹ ○Hirotaka Asai¹, Thomas J McHugh², Yoshifumi Abe¹, Jun Kaneko¹, Itaru Imayoshi^3,4,5, Ryoichiro Kageyama⁴, Tatsuhiro Hisatsune¹ 東京大学大学院　新領域創成科学研究科　先端生命科学専攻¹, 理研　脳科学総合研究センター　神経回路行動生理学研究チーム², 京都大学・白眉センター³, 京都大学・ウイルス研究所⁴, JSTさきがけ⁵ Dept Integrated Biosc, Univ of Tokyo, Kashiwa, Japan¹, Laboratory for Circuit and Behavioral Physiology, RIKEN BSI, Saitama, Japan², The Hakubi Center, Kyoto University, Japan³, Institute for Virus Research, Kyoto University, Japan⁴, PRESTO, Japan Science and Technology Agency (JST)⁵ Adult-born neurons generate at the dentate gyrus (DG) of the hippocampal formation and transmit the neural information from entorhinal cortex to CA3. It has been noted that adult-born neurons are crucial for the memory functions, but how adult-born neurons are involved in memory machinery is not fully understood. To investigate the role of adult-born neurons in the spatial memory functions including pattern separation, we generated a new triple transgenic mouse by crossing Nestin-CreER^T2 mouse with CA3-TeTX mouse. In the transgenic mouse, presynaptic transmission of adult born-neurons is attenuated due to the cell-type- and the developmental timing dependent-expression of the tetanus toxin (TeTX) light chain which inhibits normal presynaptic transmission due to the cleavage of VAMP2 proteins. Therefore, the transgenic mouse enables us to study the developmental-timing dependent function of adult-born neurons, for full expression of TeTX requires more than 4 weeks. The expression of TeTX in adult-born neurons was confirmed by using the retroviral vector encoding synaptophysin-GFP-IRES-mCherry-VAMP2 (kindly provided by Dr. Toshiaki Nakashiba: Cell 149, 1-14 (2012)). In our behavior test schedule (mice treated with tamoxifen at 8 week-olds and tested their behavior at 16 week-olds), we can attenuate the presynaptic function of new neurons, the age of which is between 4 - 8 weeks, specifically. In this condition, we performed the contextual fear discrimination task using the triple transgenic, Newborn Neuron-TeTX, and the control littermate mice. Our data suggest that the developmental-timing dependent attenuation of the presynaptic function of newborn neurons results in affected memory function as revealed in a pattern discrimination task, which is consistent with the previous report (Nakashiba et al., 2012).	P2-1-100 フルオキセチン慢性投与が間欠的な心理社会的ストレス負荷による海馬神経新生数の減少に及ぼす影響 Effects of intermittent psychosocial stress and concomitant fluoxetine treatment on hippocampal neurogenesis ○森征慶¹, 村田雄介¹, 今村聖奈¹, 鈴木陽子¹, 柳原有希¹, 美根和典¹ ○Masayoshi Mori¹, Yusuke Murata¹, Kiyona Imamura¹, Yoko Suzuki¹, Yuki Yanagihara¹, Kazunori Mine¹ 福岡大学薬学部臨床心身治療学¹ Dept Psychosom Med, Fac Pharmaceuti Sci, Univ of Fukuoka, Fukuoka, Japan¹ [Introduction] It is known that stress-induced reduction in hippocampal neurogenesis could contribute to the pathophysiology of depression. In addition, recent studies showed that hippocampal neurogenesis is involved in mechanisms underlying therapeutic effects of antidepressants. We hypothesized the changes of hippocampal neurogenesis may be useful as an indicator of antidepressive actions in animal model of depression. In order to elucidate the effect of chronic antidepressants treatment on hippocampal neurogenesis in psychosocial stressed rats, we designed this study using resident-intruder paradigm. [Methods] Sprague-Dawley rats were used. Naïve adult male intruder rats were introduced to a resident colony from which female was removed, and were defeated by male conspecifics, as indicated by submissive posture. Animals were administered intraperitoneally with saline or fluoxetine (FLX, 5mg/kg) once daily for 28 days. Intruder rats were exposed to social defeat intermittently four times within the last half 2 weeks of drug treatment. Defeated intruder rats were transcardially perfused with 4% paraformaldehyde 1 or 7 days after the last stress episode. Brains were cut into 40-μm coronal section using a freezing microtome. For stereological quantification of newly generated neurons in the dentate gyrus (DG) of hippocampus, the estimate of doublecortin (DCX)- immunoreactive cell numbers were determined using the optical fractionator procedure. [Results & Discussion] In saline-treated group, intruder rats showed a significant reduction in the number of DCX-positive cells in the DG of hippocampus compared to control rats (-24%). However, 7 days after last stress exposure, chronic treatment with FLX reversed the psychosocial stress-induced decrease in the number of DCX-positive cells. These results suggested that chronic FLX treatment blocked the stress-induced reduction in short-time survival in rat hippocampal neurons. We are also presenting the results of 1 day group.
P2-1-101 Tandospironeの長期投与は社会的ストレスを負荷したラット海馬神経新生を増加させるのか？ Does chronic tandospirone treatment have anti-stress effect on changes in hippocampal neurogenesis? ○柳原有希¹, 村田雄介¹, 森征慶¹, 松尾麻美¹, 鈴木陽子¹, 美根和典¹ ○Yuki Yanagihara¹, Yusuke Murata¹, Masayoshi Mori¹, Asami Matsuo¹, Yoko Suzuki¹, Kazunori Mine¹ 福岡大学薬学部臨床心身治療学¹ Dept Psychosom Med, Fac Pharmaceuti Sci, Univ of Fukuoka, Fukuoka, Japan¹ [Introduction] Tandospirone that is a serotonin (5-HT) 1A receptor partial agonist has been available for the treatment of anxiety symptom. In pilot study, we showed that chronic administration of tandospirone increased rat hippocampal neurogenesis in dose-dependent manner. Many reports suggested that reduction in hippocampal neurogenesis induced by stress is reversed by chronic treatment of antidepressants. We speculated that tandospirone may have positive impact on the stress-induced changes in hippocampal neurogenesis. In the present study, we aimed to investigate that chronic administration of tandospirone blocks the decrease in rat hippocampal neurogenesis caused by psychosocial stress. [Methods] Male Sprague-Dawley rats (6 weeks old) were used. Tandospirone citrate was dissolved in saline. After acclimatization, tandospirone (10mg/kg) was intraperitoneally given daily for 28 consecutive days. Two weeks after starting injection, rats were exposed to psychosocial stress using resident-intruder paradigm (4 times per 14 days). One week after the last stress exposure, rats were transcardially perfused with 4% paraformaldehyde. Brains were cut into 40-μm coronal section using a freezing microtome. For stereological quantification of newly generated neurons in the dentate gyrus (DG) of hippocampus, the estimate of doublecortin (DCX)-immunoreactive cell numbers were determined using the optical fractionator procedure. [Results] The total number of DCX-positive cells in DG of stressed rats significantly decreased compared to control rats in saline-treated group. However, tandospirone treatment counteracted the inhibitory effect of psychosocial stress. [Discussion] Our findings suggest that chronic tandospirone treatment may have anti-stress effect on changes in hippocampal neurogenesis. Further studies should be needed whether tandospirone has anti-depressive effect on behavioral responses to psychosocial stress.	P2-1-102 Communication Box法による心理的ストレス負荷が高脂肪食誘発性肥満マウスの海馬神経新生に与える影響 The effects of psychological stress induced by Communication Box on hippocampal neurogenesis in high-fat diet induced obese mice ○成澤志鎮¹, 村田雄介¹, 袈裟丸貴博¹, 森征慶¹, 柴田雄亮¹, 下野梨麻¹, 原千高², 美根和典¹ ○Yukiyasu Narisawa¹, Yusuke Murata¹, Takahiro Kesamaru¹, Masayoshi Mori¹, Yusuke Shibata¹, Rima Shimono¹, Chiaki Hara², Kazunori Mine¹ 福岡大学薬学部臨床心身治療学¹, 第一薬科大学薬物治療学² Dept Psychosom Med, Fac Pharmaceuti Sci, Univ of Fukuoka, Fukuoka, Japan¹, Dept Pharmacol, College of Pharmaceut Sci, Daiichi Univ, Fukuoka, Japan² [Introduction] Obesity is associated with the increase in the risk of depression. However, the mechanism underlying the development of depression induced by obesity remains unknown. Our preliminary study indicated that high-fat diet induced obese (HFDIO) mice exhibited behavioral abnormalities and showed the decrease in hippocampal neurogenesis, which suggesting that higher stress sensitivity in obesity is involved in the onset of depression. Thus, we designed the present study in order to investigate the effects of psychological stress using Communication Box (C.Box) on hippocampal neurogenesis in HFDIO mice. [Methods] Male ICR mice (4 weeks old) were fed by control diet or 45% high-fat diet for 7 weeks. At eleven weeks old, mice were exposed to psychological stress using C.Box for one hour per day on 3 consecutive days. They were transcardially perfused with 4% paraformaldehyde 1 week after last stress experiment. Brains were removed and coronal sections at 30μm in thickness were made. For stereological quantification of newly generated neurons in the dentate gyrus (DG) of hippocampus, the estimate of doublecortin (DCX) immunoreactive cell numbers were determined using the optical fractionators procedure. [Results] In HFDIO mice, the total number of DCX-positive cells in stress group was significantly decreased to sham control. However, no significant differences were observed for the total number of DCX-positive cells between sham control and stress group in lean mice fed by control diet. [Discussion] We indicated that the decrease in hippocampal neurogenesis induced by psychological stress was observed only in HFDIO mice. These findings suggest that stress sensitivity was increased in HFDIO mice. In order to elucidate the exact mechanism in higher stress sensitivity caused by obesity, further studies should be needed.
P2-1-103 心理的ストレス負荷が背側および腹側海馬神経新生に与える影響のマウス系統差と、行動学的反応の相関についての検討 The effect of mouse strain differences on psychological stress-induced changes in the dorsal and ventral hippocampal neurogenesis and behavioural responses ○袈裟丸貴博¹, 村田雄介¹, 成澤志鎮¹, 森征慶¹, 大森開¹, 原千高², 美根和典¹ ○Takahiro Kesamaru¹, Yusuke Murata¹, Yukiyasu Narisawa¹, Masayoshi Mori¹, Hiraku Omori¹, Chiaki Hara², Kazunori Mine¹ 福岡大学薬学部臨床心身治療学¹, 第一薬科大学薬物治療学² Dept Psychosom Med, Fac Pharmaceuti Sci, Univ of Fukuoka, Fukuoka, Japan¹, Dept Pharmacol, College of Pharmaceut Sci, Daiichi Univ, Fukuoka, Japan² [Introduction] We have previously suggested that there were mice strain differences in hormonal changes and the decrease in hippocampal neurogenesis induced by psychological stress. In the present study, we first evaluated the stress-induced changes in dorsal and ventral hippocampal neurogenesis between two mice strains. Because it has been reported that there were functional differences in dorsal (contribution to spatial learning and memory) and ventral (regulation of emotion) dentate gyrus (DG). Second, we conducted an experiment to investigate the strain differences in behavioural responses to psychological stress. [Methods] Male ICR and C57BL/6 mice (6 weeks old) were exposed to psychological stress induced by C.Box for 1h/day on 3 consecutive days. In a first set for evaluation of neurogenesis, they were transcardially perfused with 4% paraformaldehyde 1 week after last stress exposure. Brains were removed and coronal sections at 30 μm in thickness were made. For stereological quantification of newly generated neurons in the DG of hippocampus, the estimate of doublecortin (DCX)-immunoreactive cell numbers were determined using the optical fractionator procedure. Second set was used for behavioural analyses for depression and anxiety-like behaviours. [Results] In C57BL/6 mice, the total numbers of DCX-positive cells in dorsal and ventral DG were significantly decreased in stress group compared to sham control, respectively -16% for dorsal, -51% for ventral. However, no significant differences were observed for the total numbers of DCX-positive cells in dorsal and ventral DG between sham control and stress group in ICR mice. [Discussion] Because ventral DG was considered to be important in regulation of emotion, these findings suggest that stress group in C57BL/6 mice possibly represent large changes in depression and anxiety-related behaviours. We currently analyzed the effects of strain differences on several behavioural responses to psychological stress.	P2-1-104 成体で新生した顆粒細胞が嗅球投射ニューロンの異なる細胞領域に形成するシナプス Synapse formation of adult-born granule cells at distinct subcellular domains of projection neurons in the mouse olfactory bulb ○成塚裕美¹, 森憲作¹, 山口正洋¹ ○Hiromi Naritsuka¹, Kensaku Mori¹, Masahiro Yamaguchi¹ 東京大院・医・細胞分子生理学¹ Dept Physiol, Univ of Tokyo, Tokyo, Japan¹ In the olfactory bulb (OB), the major local interneurons, granule cells (GCs), are continually produced throughout adulthood. The new-born GCs form synapses with projection neurons, mitral cells (MCs) and tufted cells. Inhibition to different subcellular domains of a MC is considered to serve distinctive regulation of MC activity, but it remains unknown to which subcellular domains of MCs the new-born GCs form synapses. We found that new-born GCs form spines that contact to MC somata (perisomatic-targeting spines) as well as spines contacting to MC lateral dendrites (dendritic-targeting spines) at 10 days after the birth. At this time point, both types of spines express PSD-95 and GAD65, suggesting that they receive excitatory synaptic inputs from MCs and send inhibition to MCs. The perisomatic-targeting spines at this stage are larger than dendritic-targeting spines and they fully grow in size by 4 weeks of the birth. On the other hand, dendritic-targeting spines are still small at 4 weeks of the birth and continue to grow after this period. These observations indicate that maturation of perisomatic-targeting spines precedes that of dendritic-targeting spines.Most of new-born GCs form perisomatic-targeting spines at the early stage. A single new-born GC forms a few perisomatic-targeting spines with a small number of MCs located in close proximity, while it forms hundreds of dendritic-targeting spines with presumably many MCs. These results suggest that new-born GCs form functional synapses with a specific population of MCs through perisomatic-targeting spines before forming synaptic interactions with a large number of MCs through dendritic-targeting spines.
P2-1-105 Withdrawn

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