Diversity and comparative anatomical basis of the central nervous system of four salmonid species

Abstracts P3-e12 Time dependent shifts in baroreflex curves for sympathetic outflows induced by 2-deoxy-D-gulcose in conscious rats Yuuka Souma, Naomi Kondo, Kenju Miki Dept Integrative Physiol, Nara Women’s University, Nara, Japan The present study aimed to determine a time course of shifts in baroreflex curve for renal and lumber sympathetic nerve activity during acute glucose deprivation induced by intravenous administration of 2-deoxy-D-glucose (2DG). Wistar rats were instrumented chronically with electrodes for the measurements of renal (RSNA) and lumber (LSNA) sympathetic activity, electroencephalogram, electromyogram and electrocardiogram and catheters for the measurement of systemic arterial pressure (Pa) and vasoactive drugs infusion. At least after the 2 days recovery period, 750 mg/kg of 2DG was administered intravenously. The Pa-RSNA curve was shifted to right upward at 10 min after the 2DG administration, and then it recovered to the control curve at 60 min. The Pa-LSNA curve did not change significantly throughout the experiment. These data suggest that baroreflex curve for sympathetic outflow could be shifted in time dependent and regionally different manner during glucose deprivation in rats. doi:10.1016/j.neures.2009.09.1218

P3-e13 Distribution of vagal CGRP-immunoreactive fibers in the lower esophagus and the cardia of the stomach of the rat Tetsu Hayakawa, Sachi Kuwahara, Seishi Maeda, Koichi Tanaka, Makoto Seki Department Anatomy, Hyogo College of Medicine, Nishinomiya, Japan We have examined whether the smooth muscle fibers in the lower esophagus (LE) and the cardia of the stomach are innervated by CGRP-immunoreactive (-ir) fibers coming from the nucleus ambiguus (Am). Immunohistochemical observations revealed that there were many CGRP-ir fibers and endings in all external muscle layers. Occasionally, bundles of CGRP-ir fibers were found in the inner oblique muscle layer of the cardia. When Fluorogold was injected into the junction of the LE and the cardia, many retrogradely labeled neurons were found in the compact formation of the Am (AmC) and the dorsal motor nucleus of the vagus nerve (DMV). Double labeling with immunohistochemistry for CGRP and Fluorogold showed that almost all of the neurons in the AmC that project to the LE or the cardia contained CGRP, while no CGRP-ir neurons were found in the DMV. These results indicate that the neurons of the AmC that contain CGRP project not only to the striated muscles of the upper esophagus but also to the smooth muscles of the external layers of the LE and the cardia. doi:10.1016/j.neures.2009.09.1219

P3-e14 Responses of gastric infusion of taste substances on the gastric vagal afferent activity, and their reflex in the rat Akihiko Kitamura 1 , Akira Niijima 2 , Kunio Torii 1 , Hisayuki Uneyama 1 1

Physiol & Nutr, Inst Life Sci, Ajinomoto Co, Inc, Kawasaki, Japan; Univ Sch Med, Niigata, Japan

2

Niigata

Effects of intragastric infusion of taste substances on the activity of the vagal gastric afferent (VGA), and on the activity of the vagal celiac efferent (VCE) and the splanchnic adrenal efferent (SAE), were observed in the anesthetized rat. As the five basic taste substances, glucose (sweet), sodium chloride (NaCl; salty), quinine hydrochloride (QHCl; bitter), acetic acid (sour) and inosine monophosphate (IMP; umami) solutions were used. Results: Infusion of glucose and NaCl solutions showed no effects on VGA. Infusion of QHCl solution inhibited the activity of VGA. Infusion of acetic acid and IMP solutions activated VGA. Further, Infusion of IMP, acetic acid and QHCl solutions changed on VCE and SAE. These results suggest that taste substances in the stomach send their information through VGA to brain with different mode of signaling system of the oral taste nerve and play some roles in reflex regulation of visceral functions. doi:10.1016/j.neures.2009.09.1220

P3-e15 Differences in tryptophan hydroxylase expression in the brain of XX and XY Nile tilapia during early development K. Raghuveer 1 , Chenichery Sudhakumari 1,2 , Balasubramanian Senthilkumaran 1,2 , D. Wang 2 , Yoshitaka Nagahama 2 , Aparna Dutta-Gupta 1 1

Department of Animal Sciences, Japan; ogy, Okazaki, Japan

2

National Institute for Basic Biol-

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Brain form of Tryptophan hydroxylase (Tph) was cloned to evaluate its possible role in brain sex differentiation in the XX and XY Nile tilapia. Northern hybridization in male tilapia brain identified single transcript around 2 kb. Transient transfection of Tph in COS-7 cells converted L-tryptophan to 5-hydroxytryptophan. Tissue distribution of Tph showed high expression in brain, kidney, liver and testis. Semiquantitative RT-PCR revealed exclusive expression of Tph in male brain from 5 to 15 days after hatching (dah) while in female brain it could be detected from 20 dah. These results were further authenticated by localization of Tph using in situ hybridization in olfactory bulb-telencephalon region of 11 dah male brain. In addition Tph immunoreactivity was evident in male brain as early as 15 dah. Dimorphic localization and expression pattern of brain Tph during critical period of gonadal sex differentiation warrant an important role. doi:10.1016/j.neures.2009.09.1221

P3-e16 Effect of vasopressin on rat olfactory bulb mitral cell activity Hirofumi Hashimoto, Gareth Leng, Mike Ludwig Centre for Integrative Physiol., University of Edinburgh, UK Neural processing of olfactory signals is critical to social memory and appears to be dependent on the integrity of neuropeptides such as vasopressin (VP) and oxytocin. Previous study showed that infusion of VP directly into olfactory bulbs (OB) enhances social memory in rats, however, the role of endogenous VP in the OB is unknown. In urethane-anaesthetised rats, we examined the effect of VP and a V1a receptor antagonist on OB mitral cells (MC) using extracellular recordings. Most MC display conspicuous patterned discharge comprising prolonged intermittent bursts of action potentials. Many of these cells also display a bimodal interspike interval distribution reflecting the frequent occurrence of spike doublets. Topical administration of VP or the V1 receptor antagonist onto a small exposure of the OB significantly modified the electrical activity of these bimodal MC. VP reduced the activity quotient, and particularly the doublet firing, whereas local application of a V1 antagonist had the opposite effect. Thus, VP seems to be a retrograde signal that filters activation of the MC arising from the glomeruli. doi:10.1016/j.neures.2009.09.1222

P3-e17 Contribution of TRPV1 to the osmosensitivity in the synaptic inputs to the magnocellular neurosecretory cells in the supraoptic nucleus Toru Yokoyama, Toyoaki Ohbuchi, Tosihisa Nagatomo, Yoichi Ueta Dept Physiol, Sch Med, Univ of Occup & Environ Health, Kitakyushu, Japan The magnocellular neurosecretory cells (MNCs) in the supraoptic nucleus (SON) project their axons to the posterior pituitary and secrete vasopressin in the systemic circulation. The neuronal activity of MNCs is modulated by synaptic inputs and humoral factors such as osmotic change. Recent study demonstrated that Nterminal splice variant of transient receptor potential vanilloid 1 (TRPV1) may be essential for osmosensory transduction in the SON. Here, we examined the effects of TRPV1 to the osmosensitivity on excitatory synaptic inputs to the MNCs in the SON by using whole-cell patch-clamp recordings in in vitro mice slice preparation. Hyperosmolarity-indudced potentiation of miniature excitatory postsynaptic currents were significantly attenuated in the SON of TRPV1-knockout mice compared with wild-type. This result suggests that TRPV1 may be involved in osmotic modulation of excitatory synaptic inputs to the MNCs in the SON. doi:10.1016/j.neures.2009.09.1223

P3-e18 Diversity and comparative anatomical basis of the central nervous system of four salmonid species Tamaki Ohya Laboratory of Endocrinology, Graduate School of Integrated Science, Yokohama City University, Japan Brain studies began in ancient Egypt, speculations on vertebrate brain evolution occurred only much later. Subsequently, views of brain evolution have been shaped by a complex interplay of theory and technique. With the development of histological techniques, research shifted to descriptions of cellular structure, cellular aggregates and their putative interconnections. Following the publication of The Comparative Anatomy of the Nervous System of Vertebrates by Ariens Kappers, Huber, and Crosby in 1936, there followed a period of stasis, after which biological views of evolution were radically altered by the confluence of genetics, paleontology, and systematics, termed the Evolutionary Synthesis. The development of new experimental techniques for establishing neural connections resulted in a new flowering of comparative neuroanatomy. Present digital contents were diversity and comparative anatomical aspect of four salmonid fish, rainbow trout, chum salmon, masu

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salmon, and sockeye salmon, referred The Central Nervous System of Vertebrates of Rudolf Nieuwenhuys, published in 1998. doi:10.1016/j.neures.2009.09.1224

P3-e19 Distribution of Scaffold attachment factor B in the rat brain Takashi Hashimoto, Ken-ichi Matsuda, Mitsuhiro Kawata Dept of Anatomy and Neurobiology, Kyoto Prefectural University of Medicine, Kyoto, Japan Scaffold attachment factor (SAFB) 1 and 2 are implicated in various cellular processes (e.g. chromatin organization), and they are also known as corepressors of estrogen receptor alpha (ER␣). Although their mRNAs are expressed ubiquitously, little is known about the regional difference of SAFB proteins in the brain. In this study, we examined localization of SAFB proteins in adult rat brain. SAFB1/2 immunoreactivity (ir) was observed in almost all the region, and particularly intense labeling was seen in the hippocampus, arcuate nucleus of the hypothalamus and medial amygdala, where ER␣ is expressed. In vitro analysis showed that SAFB1-ir was expressed in the nucleus of cultured neurons, astrocytes and oligodendrocytes, whereas SAFB2-ir was detected in both nucleus and cytoplasm of these cells. These results suggest that SAFB1 is broadly coexpressed with SAFB2 in the brain and their interaction with ER␣ is under investigation. doi:10.1016/j.neures.2009.09.1225

P3-e20 Neuroprotective effect of estradiol on methylmercuryinduced neuronal cell toxicity in rat hippocampal slices Takeshi Yamazaki 1 , Shota Komatsu 1 , Masahiro Onizaki 1 , Takao Mukuda 1 , Atsuhiko Ishida 1 , Shogo Sakata 1 , Suguru Kawato 2 , Megumi Yamamoto 3 1

Grad Sch of Inte Arts and Sci, Hiroshima Univ, Japan; 2 Grad Sch of Arts and Sci, the Univ of Tokyo, CREST, Japan; 3 Natl Inst for Minamata Disease, Japan

Hippocampus synthesizes estradiol as a neurosteroid. The brain-derived estradiol may have a neuroprotective function. Here we analyzed effect of estradiol on neurotoxicity of methylmercury in hippocampal slice cultures. Hippocampal slices from 10-day-old male rat were treated with methylmercury for 24 hours. Neuronal death was detected by propidium iodide (PI) uptake. About 50% of neurons at dentate gyrus were stained by PI after the treatment with 1 ␮M methylmercury. The damaged neurons at CA1 and CA3 regions were less than 10%. Pretreatment of hippocampal slices with estradiol decreased the neurotoxic effect in a dose-dependent manner. The toxic effect of methylmercury was enhanced by pretreatment of hippocampus with letrozole, an inhibitor of estradiol synthesis. The data indicate that (1) neurotoxic effect of methylmercury is reduced by estradiol, and (2) hippocampus-derived estradiol is neuroprotective. doi:10.1016/j.neures.2009.09.1226

P3-e22 Acceleration of anovulatoy condition in over exercise by midbrain raphe lesions in female rats Hideo Shimizu, Korehito Yamanouchi Neuroendocrinol, Waseda Univ, Saitama, Japan Under stressful condition, serotonin in the brain increases. Sertonergic neurons in the raphe nucleus are involved in regulation of ovulation. Over exercise is known to induce anovulatory syndrome in mammals including man. In this experiment, to clarify the role of serotonergic neurons in control of estrous cycle under stress condition, the dorsal (DRN) or median (MRN) raphe nuclei was lesioned and the rats were forced to run in a electric drive wheel during 30 min daily for 15 days. Through the tests, vaginal smear was checked.As the result, 6 of 9 rats showed normal estrous cycle during 15 days. In contrast, only each 1 of 9 DRN lesion and 8 MRN lesion rats, respectively showed normal cycle. First day of disappearance of proestrus of vaginal smear was recognized as the day of onset of anovulatory condition. The onset days (median) of the DRN lesion and MRN lesion groups were 7 and 3 days respectively after start of running. These results indicate that the DRN and MRN are important role in prevention of stress condition by over exercise in estrous cycle of female rats. doi:10.1016/j.neures.2009.09.1228

P3-e23 Effects of p-chlorophenylalanine on density of serotoninimmunoreactive cells in raphe nuclei of rats: Sex difference Hiroyuki Ito, Korehito Yamanouchi Neuroendocrinol,Waseda University,Saitama, Japan The serotonergic neurons in the dorsal raphe nucleus play an important role in regulating reproductive phenomena. However, the sex difference of nature of serotonergic neurons in the raphe nucleus has not been found, yet. To clarify this point, sensitivity of p-chlorophenylalanine (pCPA) to serotonergic neurons in the raphe nuclei was analyzed. Gonadectomized female (OVX) and male (OCX) rats were treated with 100 mg/kg b.wt pCPA or saline daily for 4 day and number of serotonin-immunoreactive (5-HT-ir) cells were counted in the dorsal and median raphe nuclues (DRN and MRN, respectively). As the results, densities of 5-HT-ir cells of pCPA-treated OVX and OCX rats were lower than those in the non-treated groups in the DRN and MRN. On the other hand, number of 5-HT-ir cells in the pCPA-OCX group was seen only half of those in the pCPA-OVX group in both raphe nuclei. These results suggest that sensitivities of serotonergic neurons to pCPA in the raphe nuclei are sexually dimorphic. doi:10.1016/j.neures.2009.09.1229

P3-e24 Proteomics analysis of changes in proteins in rat sexually dimorphic hypothalamic nucleus during the critical period Takashi Iwakura 1,2 , Shinji Tukahara 3 , Mumeko c Tsuda 1 , Kazuhiro Sano 1 , Taiichi Uchimura 1 , Sonoko Ogawa 1 , Takashi Shiga 1 , Tomohiro Kato 4 , Ritsuko Ohtani-Kaneko 2 1

P3-e21 Role of prolactin-releasing peptide in stress-induced energy expenditure Yuki Takayanagi, Tatsushi Onaka Dept Physiol, Jichi Med Univ, Tochigi, Japan Prolactin-releasing peptide (PrRP) has been shown to play a role in the control of energy metabolism and stress responses. We found that PrRP-deficient mice show adult-onset hyperphagia and obesity. PrRP administration has been reported to increase energy consumption. However, we demonstrated that basal oxygen consumption is not significantly different between PrRP-deficient and wild-type animals. Thus, metabolic functions of endogenous PrRP are not fully elucidated. In the present study, we examined oxygen consumption in PrRP-deficient mice under cage-switch stress. Cage-switch stress increased oxygen consumption in wild-type animals. At the age of 9 weeks, stress-induced increase in oxygen consumption was not significantly different between PrRP-deficient and wild-type animals. However, the increase was significantly lower in PrRP-deficient mice at the age of 16 weeks, just prior to the age when PrRP-deficient mice begun to show clear obesity. These results suggest that endogenous PrRP plays an important role in stress-induced energy expenditure. doi:10.1016/j.neures.2009.09.1227

Univ of Tsukuba Grad Sch of Cmprehensive Human Sci, Tukuba, Japan; Dept LIfe Sci, Toyo Univ, Gunma, Japan; 3 Natl Inst EnviroStudies, Japan; 4 Dept Biochem, St Marianna University, Japan 2

Our aim is to find proteins functioning in sexual differentiation of the brain, especially in the anteroventral periventricular nucleus (AVPV) of rats during the critical period. Developing AVPV was isolated from rat brain on postnatal day 1 (PD1) and 6 (PD6). Differentially expressed proteins between the sexes were identified in protein extracts by two dimensional fluorescence difference gel electrophoresis (2D-DIGE) followed by MALDI-TOF-MS or Synapt MS. We identified multiple proteins which showed sexually dimorphic expression on PD1 but not on PD 6. This was further confirmed at mRNA levels. The identification of time-specific, sexually dimorphic proteins here would promote understanding of sexual differentiation of the brain. doi:10.1016/j.neures.2009.09.1230

P3-e25 Myosin II modulates a size of exocytotic fusion pore in neuroendocrine cells Ryo Aoki 1 , Tetsuya Kitaguchi 2 , Atsushi Miyawaki 2 , Takashi 1 Tsuboi 1

Dept of Life Sci, Grad Sch of Arts and Sci, Univ of Tokyo, Japan; JST, Saitama, Japan

2

ERATO,

It has been reported that myosin II (MyoII) and F-actin regulate the size of fusion pore of dense-core vesicle exocytosis in neuroendocrine cells. However, the precise function of MyoII in dense-core vesicle exocytosis was largely unknown. We have investigated the role of MyoII in regulating exocytosis in neuroendocrine