一般口演（Oral）

Oral Biological rhythm 一般口演生体リズム

7月26日（金）8:30～8:45　第7会場（朱鷺メッセ　2F　201B） 2O-07m1-1 視交叉上核バソプレシンニューロンからのGABA放出は中枢概日時計の出力のタイミングを制御する Michihiro Mieda（三枝理博）¹，Emi Hasegawa（長谷川恵美）²，Yusuke Tsuno（津野祐輔）¹，Takashi Maejima（前島隆司）¹ ¹金沢大医統合神経生理学 ²筑波大国際統合睡眠医科学研 The hypothalamic suprachiasmatic nucleus (SCN) serves as the master circadian clock in the mammals. The SCN neuronal circuit consists mostly of GABAergic neurons that can generate independent circadian oscillations of clock gene expression and neuronal activity. These GABAergic neurons include arginine vasopressin (AVP) producing neurons in the dorsomedial part and vasoactive intestinal peptide producing neurons in the ventrolateral part of the SCN. Recently, we have shown that AVP neurons have a pacemaking function to determine the length of circadian cycle. However, the roles of GABA in the SCN network remain controversial. In this study, to investigate a functional role of the GABAergic synaptic output from AVP neurons in controlling the circadian rhythmicity, we have analyzed AVP neuron-specific vesicular GABA transporter deficient mice (AVP-Vgat^-/- mice). First, we found that miniature GABAergic synaptic currents (mGPSCs) with smaller amplitude were more frequently detected in light phase than in dark phase from control AVP neurons. However, such a circadian change of the mGPSCs occurrence could not be seen in AVP-Vgat^-/- mice. These data suggested that the smaller mGPSCs derived from AVP neuronal terminals are practically eliminated in AVP-Vgat-/- mice. In constant dark condition, AVP-Vgat^-/- mice showed marked lengthening more than 5 hours and also a splitting pattern in activity time of behavioral circadian rhythm. Synchrony of cellular circadian oscillations in the SCN monitored by PER2::LUC reporters was not attenuated, whereas phase relationships between the SCN cellular clocks and the circadian morning/evening locomotor activities altered significantly in AVP-Vgat^-/- mice. Thus, GABAergic transmission from AVP neurons regulates the timing of SCN output to delineate correct circadian behavior rhythm.		7月26日（金）8:45～9:00　第7会場（朱鷺メッセ　2F　201B） 2O-07m1-2 Palmitate Changes Circadian Clock Gene Expression in Hypothalamic Cells Anne-Marie Neumann（Neumann Anne-Marie），Merle Brockmann（Brockmann Merle），Henrik Oster（Oster Henrik） Institute of Neurobiology, Center of Brain, Behavior & Metabolism, University of Luebeck, Luebeck, Germany Circadian clocks, the endocrine system and energy metabolism are tightly linked and mutually influence one another. Moreover, chronodisruption is an increasingly recognized risk factor for the development of obesity. Obese patients show a heavily disturbed blood lipid levels including increased concentrations of free fatty acids compared to healthy individuals. Among these fatty acids, palmitate is the most abundant in blood as well as in Western style diets and was shown to disrupt circadian clocks and cell function of hepatocytes and β-cells. We hypothesized, that diurnal metabolic signals such as palmitate may not only affect peripheral tissues but also clocks in food regulatory centers in the hypothalamus. To test this, we used immortalized murine hypothalamic neuronal cells and investigated the effect of palmitate on clock gene mRNA transcription. Acute supplementation of 2 mM palmitate increased expression of Bmal1 (after 8h p < 0.001), Per2 (p < 0.001), Rev-Erbα (p < 0.01) while Clock and Per1 were unaffected. The fatty acid target gene and potential BMAL1 regulator, Pgc1α, was also acutely increased (p < 0.0001). In synchronized cells, rhythms of Bmal1 and Clock mRNA as well as the expression of Pparα and Pgc1α were altered in the presence of 1 mM palmitate. To evaluate the effect of palmitate on hypothalamic clock rhythmicity, cells were robustly transfected to express the luciferase reporter enzyme under the control of the promotor of Bmal1. We found palmitate to change phase, damping and amplitude of Bmal1 expression rhythms in a dose-dependent manner. In summary, we were able to show the clock disrupting potential of dietary fatty acids such as palmitate on hypothalamic clock function. These data may help to better understand the pathogenesis of obesity and to find ways to stop the vicious cycle of chronodisruption and disturbed energy metabolism.

7月26日（金）9:00～9:15　第7会場（朱鷺メッセ　2F　201B） 2O-07m1-3 時差環境下において概日行動リズムを担うバソプレッシンシグナル Yoshiaki Yamaguchi（山口賀章）¹，Hitoshi Okamura（岡村均）² ¹京都大院薬システムバイオ ²京都大院薬分子脳科学 It is indispensable for us today that 24/7 services in commerce, industry, and social facilities. Roughly, 20% of the working population in developed countries engage in some sort of shiftwork. Accumulating evidence indicates that shiftwork is a risk factor for cancers, obesity, gastric ulcers, and heart diseases. Studies using animals kept in a chronic jet lag (CJL) condition where a light-dark (LD) cycle is repeatedly shifted at a certain interval to mimic an environment of shift workers have also related CJL to more rapid tumor progression, dysregulated inflammation, obesity, and heart diseases. In particular, a CJL exposure even induced a sudden death in aged mice (Davidson et al., 2006). Dissociation between the internal time and the environmental LD schedule has been thought to the main cause for this sudden death. However, the molecular and neural mechanism(s) for this dissociation has not been clarified yet. Circadian rhythm is an evolutionarily and highly conserved trait of bacteria, plants, insects, and animals which coordinates physiology and behavior with the 24 h solar time to anticipate and adapt to daily environmental changes. Circadian rhythm is not generated subordinately by the environmental LD cycle, but is autonomously driven by the internal timing system comprised of a master pacemaker located in the suprachiasmatic nucleus (SCN) of the anterior hypothalamus. The coherent output signal from the SCN clock neurons synchronizes cellular clocks in periphery. We recently found that jet lag, accompanied by an abrupt change of the LD cycle, profoundly affected the circadian oscillatory characteristics of the SCN neurons. We identified that the neuronal circuit mediated by arginine vasopressin (AVP)/V1 receptor signaling in the SCN plays a crucial role in the resilience of the circadian clock to jet lag; AVP receptor V1a and V1b double knockout (V1aV1bDKO) mice did not show any jet-lag symptoms in the rhythms of locomotor activity, clock gene expression, and body temperature. This feature of rapid re-entrainment increased the survival rate under chronic jet lag in aged V1aV1bDKO mice.		7月26日（金）9:15～9:30　第7会場（朱鷺メッセ　2F　201B） 2O-07m1-4 視交叉上核ガストリン放出ペプチド産生ニューロンのサーカディアンリズム形成における役割 Ruth Li（李若詩）^1,2，Arisa Hirano（平野有沙）¹，Ran Inoue（井上蘭）³，Hisashi Mori（森寿）³，Takeshi Sakurai（櫻井武）¹ ¹国際統合睡眠医科学研究機構 ²筑波大学医学群医学類 ³富山大学大学院医学薬学研究部分子神経科学講座 The suprachiasmatic nucleus (SCN) of the hypothalamus is known to be responsible for controlling the circadian rhythm. Anatomically, the SCN consists of the shell (outer layer) and the core (inner layer). Both parts contain different populations of neurons--the shell consists of mostly arginine vasopressin (AVP) neurons, while the core consists of mostly vasoactive intestinal peptide (VIP) and gastrin-releasing peptide (GRP) neurons. Compared to AVP and VIP neurons, GRP neurons have a smaller population, and the roles they play in regulating circadian rhythm also remain largely unknown. Through the use of a newly generated mouse line--the GRP-iCre knock-in (KI) mice--we managed to clarify the role of GRP neurons in the SCN. We traced the neuronal projections of GRP neurons in the SCN through restricted expressions of GFP by injecting a Cre-activatable adeno-associated virus serotype 2 (AAV2) vector carrying GFP in the SCN of GRP-iCre KI heterozygous mice. We found that GRP neurons send projections to the ventromedial preoptic nucleus, ventrolateral preoptic nucleus, paraventricular thalamic nucleus, central medial thalamic nucleus, and dorsomedial hypothalamic nucleus, but avoid the ventromedial hypothalamic nucleus and arcuate hypothalamic nucleus. We have also examined the effect of inhibition of these cells on behavior. We focally injected Cre-dependent AAV2 carrying tetanus toxin light chain, in the GRP-iCre KI heterozygous mice, and monitored their locomotor activities. The mice with inhibition of GRP neurons in the SCN showed normal locomotor activity rhythms in the normal light-dark cycle, but became arrhythmic in constant darkness. From these results, we postulated that the GRP neurons in the SCN may play a role in regulating the circadian behavioral rhythm in the absence of light entrainment.