神経化学教育口演セッション3 Cerebellum
O3-8-5-1 アルドステロン短期投与による神経機能制御 Aldosterone enhanced release of neurotransmitter in cultured neurons ○安達直樹2,3, 沼川忠広2,3, 岡本明理1,2, 増尾好則1, 功刀浩2,3 ○Akari Okamoto1,2, Tadahiro Numakawa2,3, Naoki Adachi2,3, Yoshinori Masuo1, Hiroshi Kunugi2,3 東邦大学　理学部　生物学科1, 国立精神・神経医療研究センター　神経研究所　疾病研究第三部2, 戦略的創造研究推進事業、科学技術振興機構3 Dept Bio, Univ of Toho, Chiba, Japan1, Department of Mental Disorder Research, National Institute of Neuroscience, NCNP, Japan2, CREST, JST, Saitama, Japan3 Many reports suggest that chronic glucocorticoid exposure is involved in the pathophysiology of brain disorders including depression, and we previously confirmed decreased neuronal function after glucocorticoid exposure in cultured neurons (Numakawa et al., Neuroscience in press). On the other hand, there is very little information on acute action of glucocorticoid in neurons. In the present study, we found that aldosterone, an agonist for mineralocorticoid receptor (high affinity receptor for glucocorticoid) enhanced the release of glutamate, an excitatory neurotransmitter in cultured cortical neurons. Furthermore, we found that ERK (Extracellular Signal-regulated Kinase), which is one of intracellular signaling pathways, was stimulated following aldosterone application. As evidences including ours indicate that the ERK pathway is critical for synaptic plasticity such as neurotransmission, it is possible that aldosterone rapidly regulates intracellular signaling for release of neurotransmitter in the central nervous system neurons.	O3-8-5-2 ラットメラニン凝集ホルモン受容体1の構造活性相関－Gタンパク質選択機構 The structure-activity relationship in rat melanin-concentrating hormone receptor 1 -Structural determinants for G-protein selectivity ○濱本明恵1, 小林勇喜1, 斎藤祐見子1 ○Akie Hamamoto1, Yuki Kobayashi1, Yumiko Saito1 広島大学大学院　総合科学研究科　生命科学1 Graduate School of Integrated Arts and Sciences, Hiroshima University, Hiroshima1 Melanin-concentrating hormone (MCH) receptor 1 (MCHR1) is a G-protein coupled receptor (GPCR) that is widely expressed at high levels in the brain. MCH-MCHR1 system is linked to a variety of physiological functions centered on energy homeostasis and mood. Although knowledge concerning structural determinants of mammal MCHR1 activation has been accumulated, there is no answer regarding selectivity mechanisms between MCHR1 and different subtypes of Gα proteins. Our preliminary studies have shown that the signaling properties of goldfish MCHR1 and frog MCHR1 are quite different from mammalian MCHR1. That is, mammalian MCHR1 promiscuously couples to both Gi/o and Gq, whereas either goldfish or frog MCHR1 exclusively couples to Gq. Therefore, we take advantage of such a difference and try to identify amino acid residues of rat MCHR1 that is specifically responsible for Gi/o coupling. We first made multiple sequence alignment among rat, goldfish and frog MCHR1, and systematically designed a series of substitution in rat MCHR1 containing the mutated helix and/or intracellular cytoplasmic loop. Next, using transiently transfection into HEK293T cells, the amounts of receptor expression and glycosylation pattern of mutations were examined by Western blotting. We further analyzed the effect of mutations on Gi/o activity in calcium mobilization with Gi/o-sensitive pertussis toxin, and then judged by Gi/o-dependent GTPγS-binding assay. The 6sub/i3 mutant, in which all four residues in the 3rd intracellular loop with two residues in helix 5 were simultaneously substituted, exhibited significantly increased the EC50 value in GTPγS-binding but intact value in Gq-dependent calcium mobilization. Further, 6sub/i2 mutant, with mutation of all six residues in the 2nd intracellular loop, also led to the characteristic phenotype in terms of selective G-protein activation. Further investigation base on our findings could be useful in building a 3D model of MCHR1 in complex with Gi/o.
O3-8-5-3 シェーファー側枝LTPに対するパルブアルブミン陽性神経細胞を介したニューロプシンシグナリングの関与 Involvement of parvalbumin neurons on Schaffer-collateral long term potentiation via neuropsin signaling ○鈴木春満1, 石川保幸1, 塩坂貞夫1 ○Harumitsu Suzuki1, Yasuyuki Ishikawa1, Sadao Shiosaka1 奈良先端大　バイオ　神経機能科学1 Dept Bio Sci, NAIST, Nara1 Neuropsin(NP) is known to contribute plasticity functions in hippocampus areas and amygdala. Deficiency of neuropsin causes a significant impairment of early-phase of long-term potentiation (LTP) in the Schaffer collateral pathway and consequently behavioral deficient such as hippocampus-dependent memory in the Y maze and Morris water maze. Recently, NP was revealed to induce ErbB4 signaling via ErbB4 expressing inhibitory neurons to regulate excitatory neurons. However, how the CA1 pyramidal neurons which receives Schaffer-collateral LTP is controlled from inhibitory NP signaling remains elusive. To reveal it, we focused on how to innervate excitatory neurons by parvalbumin(PV) positive neurons that also express ErbB4 using immunohistochemistry. PV neurons are scattered in the CA1 and CA3 areas of hippocampus, especially stratum oriens and radiatum layers. A small number of them also exist in stratum radiatum and dentate gyrus(DG). In NP deficient mice, the PV positive neurons were changed in number in some layers of hippocampus compared wild type mice; increased in stratum oriens of the CA3 subfield and the hilus of DG; decreased in stratum pyramidale of the CA3 subfield and granule cell layer of DG. Since NP deficient mice defect to induce early phase of LTP, interaction between PV and CA1 pyramidal neurons might be important to induce LTP via NP signaling.	O3-8-5-4 哺乳類のBrn-2/Pou3f2は仔育ておよび社会性行動に重要である―先祖返りマウスの解析から脳の進化を探る― Mammalian Brn-2/Pou3f2 is important for the parenting and social behaviors - the research on the brain evolution with the analysis of reversion mice - ○矢田紗織1, 那須信1, 伊藤円1, 吉田進昭2, 植田信太郎1 ○Saori Yada1, Makoto Nasu1, Meguru Ito1, Nobuaki Yoshida2, Shintaroh Ueda1 東大・院理・生科1, 東大・医科研・システム疾患モデル研究センター2 Dept. of Biol. Sci., Grad. Sch. of Sci., The Univ. of Tokyo, Tokyo1, Cen. of. Exp. Med. and Sys. Biol., Inst. Of Med. Sci., The Univ. of Tokyo2 Brn-2/Pou3f2 is expressed in the central nervous system of all vertebrates. Brn-2 knock-out mice exhibited morphological mutations at the cerebrum and the diencephalon and died within a few days after birth. Thus, Brn-2 is considered to be an important gene for the morphologic formation in the vertebrate brain. There are three homopolymeric amino acids (HPAAs) in mice Brn-2. These three HPAAs only exist in amniotes (from reptiles to mammals), whereas there are no HPAAs in amphibia and fishes. Except for HPAAs regions, Brn-2 sequence was highly conserved among all vertebrates. HPAAs are generally known to have some function in vivo. Therefore, it is assumed that three HPAAs in Brn-2 have been acquired through the evolution in vertebrates and play an important role in the brain. In this study we investigated the function of Brn-2 HPAAs and the mechanism of the brain evolution by analyzing knock-in mice which have amphibian Brn-2. We generated Xenopus tropicalis Brn-2 (xBrn-2) knock-in (KI) mice by homologous recombination between mouse Brn-2 and xBrn-2. KI mice have only amphibian-type Brn-2. We found that the weaning rate when KI mice were dams was markedly lower than in wild-type dams. Because genotypes of dead infants were in accord with Mendelian ratio, it suggests that this low weaning rate depends on dam genotypes. We therefore tried retrieving test to examine maternal behaviors on female mice. These results have revealed that KI mice showed significantly low value, that is, they were mutated in one of the maternal behavior. We next examined an olfactory memory test because olfaction is important for parenting on mice. It resulted in loss of olfactory memory on KI mice compared with Wt. Furthermore, some other behavioral test showed higher anxiety and fear on KI mice. Consequently, it suggests that the change of Brn-2 sequence through the evolution from amphibia to mammals contributes to complex social behaviors in mammals such as the parenting and the emotion.

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