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シンポジウム 28 人工冬眠の基盤となる低温脳機能学Cold Brain Scienceの創生に向けて 28 Towards Cold Brain Science Underpinning Artificial Hibernation Technology 座長：櫻井 武（筑波大学医学医療系）・宮道 和成（理化学研究所 生命機能科学研究センター） 2022年7月1日　16:10～16:42　沖縄コンベンションセンター 会議場A1　第2会場 2S02e-01 冬眠様状態における概日振動体の動態と機能 Dynamics and function of the circadian oscillator during hibernation-like state in mice *平野 有沙(1)、高橋 徹(1)、南部 美友(2)、田中 和正(2)、櫻井 武(1) 1. 筑波大学、2. 沖縄科学技術大学院大学 *Arisa Hirano(1), Tohru Takahashi(1), Nambu Miyu(2), Tanaka kazumasa(2), Sakurai Takeshi(1) 1. University of Tsukuba, 2. OIST Keyword: Circadian clock, Circadian rhythms, hibernation The circadian clock system regulates the 24 hours physiological rhythms in various organisms. In mammals, the suprachiasmatic nucleus (SCN) in the hypothalamus is known as the master clock responsible for generation and synchronization of circadian rhythms in peripheral tissues. The circadian clocks are driven by a transcription-translation based negative feedback loop and multiple steps of mRNA/protein modifications. Although the clock oscillation is composed of biochemical reactions, the circadian period is not so much affected by fluctuation of environmental and/or internal temperature, which is known as temperature compensation. Recently, long-term hibernation-like hypothermia and hypometabolic state was reported in mice, which are not natural hibernator (Takahashi et al., Nature, 2020). Pyroglutamylated RFamide peptide (QRFP)-positive neurons in the anteroventral periventricular nucleus (AVPe) hypothalamus region (called as Q neurons) are responsible for this phenomenon. Pharmacological excitation of these neurons triggered decrease of body temperature and metabolism (oxygen consumption) and it lasted for several days. To examine the brain function in the hypothermic and hypometabolic state, we analyzed the circadian oscillator at behavioral, cellular and molecular levels in the SCN and peripheral tissues. In vivo imaging of PER2::LUC, which is fused protein of LUC and a core clock protein PER2, revealed that the molecular circadian oscillator persisted in hibernation-like hypothermic state, while the cellular metabolic rate is supposed to be largely decreased. On the other hand, tissue culture at low temperature (25 degree) significantly damped the molecular rhythms, suggesting the specific mechanism keeping the clock function in vivo in low temperature environment. Our findings also demonstrated that the temperature compensation of the circadian clock is observed in mammals in vivo. 2022年7月1日　16:42～17:04　沖縄コンベンションセンター 会議場A1　第2会場 2S02e-02 概日時計の温度補償性 -低温Ca(2+)シグナルによる生化学振動の制御- Temperature compensation of circadian clock -Regulation of biochemical oscillation by cold Ca(2+) signaling- *金 尚宏(1)、王 幸慈(2)、岩本 隆宏(3)、深田 吉孝(4) 1. 名古屋大学トランスフォーマティブ生命分子研究所、2. 東京大学、3. 福岡大学、4. 東京大学 *Naohiro Kon Kon(1), Wang hsintzu(2), Takahiro Iwamoto(3), Yoshitaka Fukada(4) 1. Nagoya University , 2. University of Tokyo, 3. Fukuoka University, 4. University of Tokyo Keyword: circadian clock , temperature compensation of , cold Ca2+ signaling, CaMKII Circadian clock generates many physiological rhythms. In mammals, most of the rhythms are generated by transcriptional rhythms based on transcriptional and translational feedback loops (TTFL). Importantly, period lengths of the biochemical oscillations are almost constant in the range of physiological temperatures, and the property is called as temperature compensation. In order to understand the mechanism of the temperature compensation, we screened small-molecule inhibitors by using mammalian cultured cells expressing luciferase reporter of the transcriptional rhythms. The temperature compensation was compromised in the presence of an inhibitor of NCX (KB-R7943, SEA0400) or CaMKII (KN-93). Further analysis revealed that lowering the temperature enhances NCX-dependent Ca2+ influx to activate CaMKII. CaMKII facilitates heterodimerization of CLOCK and BMAL1, bHLH transcription factors, thereby activating gene expression through E-box DNA elements. Thus, NCX-dependent cold Ca2+-CaMKII signaling compensates for deceleration of TTFL at lower temperatures. We found that the Ca2+ signaling is essential for maintenance of amplitude of mouse behavioral rhythms especially at cold temperature. (Kon et al., Genes and Development, 2014; Kon et al. Science Advances, 2021). 2022年7月1日　17:04～17:26　沖縄コンベンションセンター 会議場A1　第2会場 2S02e-03 人工冬眠によるてんかん進行の抑制 Substantial suppression in the progression of the medial temporal lobe epilepsy after induction of the hibernation-like state タト ムホトゥ(1)、リン ユジュ(1)、南部 美友(1)、大山 薫(1)、平野 有沙(2)、櫻井 武(2)、*田中 和正(1) 1. 沖縄科学技術大学院大学（OIST）、2. 筑波大学 国際統合睡眠医科学研究機構（WPI-IIIS） Thato Mary Mokhothu(1), Yu-Ju Lin(1), Miyu Fudge Nambu(1), Kaoru Ohyama(1), Arisa Hirano(2), Takeshi Sakurai(2), *Kazumasa Z Tanaka(1) 1. Okinawa Institute of Science and Technology Graduate University, Okinawa, Japan, 2. International Institute for Integrative Sleep Medicine (WPI-IIIS), University of Tsukuba Keyword: temporal lobe epilepsy, hibernation, latent phase Temporal lobe epilepsy (TLE) is a chronic neuronal disorder initiated by abnormal hyperactivity in the temporal lobe. It is characterized by recurrent and unprovoked seizure activities and propagates to other brain areas as it progresses. The progression of TLE consists of three distinct phases; the acute phase, where a brain insult causes a prolonged seizure; the latent phase, where no behavioral seizures are observed; and the chronic phase, where spontaneous recurrent seizures (SRS) emerge. Despite the severity of SRS, the physiological mechanisms leading to the chronic phase remain to be elucidated. Although it is still controversial, the neuronal activities during the latent phase are hypothesized to play a causal role in TLE progression. To test this idea, we used recently developed transgenic mice to induce a hibernation-like hypometabolic state (Q-neuron-induced hypothermia and hypometabolism, QIH). During QIH, the neuronal activity throughout the central nervous system is substantially reduced without leaving abnormality after arousal from QIH. To induce TLE in mice, we used the pilocarpine model, which well captured the three phases of progression while keeping the mortality rate low. After the acute phase, we induced QIH to reduce neuronal activities for a long duration during the latent phase. Our preliminary observation revealed a substantial delay in SRS onset after recovery from QIH. This finding suggests artificially-induced hypothermia and hypometabolism as a novel therapeutic approach to prevent the progression of TLE. 2022年7月1日　17:26～17:48　沖縄コンベンションセンター 会議場A1　第2会場 2S02e-04 ライフステージやストレスにより誘導される神経内分泌機能のモードシフト Life Sage- and Stress-induced Mode Shift of Neuroendocrine Functions in Mice *宮道 和成(1) 1. 理化学研究所 生命機能科学研究センター *Kazunari Miyamichi(1) 1. RIKEN BDR Keyword: Hypothalamus, Kisspeptin, Oxytocin, photometry Diverse body functions and their homeostasis are regulated by orchestrated actions of various hormonal systems, each of which is regulated by a unique neural population in the hypothalamus. Until recently, blood sampling is an almost solely available way to measure hormonal dynamics. However, such an endocrinological method is not only invasive to animals but also limited by low temporal resolution. Direct monitoring neural activity patterns of specific hormone regulators in the brain may improve the temporal resolution in the studies of hormonal dynamics. Here I discuss two examples of chronic in vivo Ca2+ imaging of the central regulators for neuroendocrine systems in freely moving animals: oxytocin (OT) for maternal functions and kisspeptin (Kiss) for gonadotropin release. Pulsatile release of OT mediates uterine contraction during parturition and milk ejection during lactation. These OT pulses are generated by unique activity patterns of the central OT neurons. By fiber-photometry-based chronic Ca2+ imaging, we showed that pulsatile activities of OT neurons only appeared in mothers, grew as mothers experienced lactation, and quickly terminated after weaning of pups. We also demonstrated the pharmaco-genetic manipulation of pulsatile activities of OT neurons via activating a prominent pre-synaptic structure of OT neurons defined by retrograde trans-synaptic tracing. Thus, our study opens a new avenue for the neuroscience of maternal neuroendocrine functions. Pulsatile release of gonadotropin, which is essential for germline growth, is mediated by the central pattern generator of gonadotropin-releasing hormone (GnRH), the Kiss neurons in the hypothalamic arcuate nucleus. We established chronic Ca2+ imaging of Kiss neurons to reveal how various stressors, including restraint and fasting, can potently and acutely suppress the pulsatile activities of Kiss neurons. In this seminar, I will discuss our working progress on dissecting neural (circuit) mechanisms of the stress-mediated decline of Kiss neural activities. Our study will form a foundation to understand how basic functions of the hypothalamus may be altered under induced hypothermic conditions. 2022年7月1日　17:48～18:10　沖縄コンベンションセンター 会議場A1　第2会場 2S02e-05 冬眠は救急医療に有用か？ 〜脳から始まる能動的低代謝による急性期疾患の管理〜 Can hibernation save lives in emergency medicine? Designing acute disease management via brain-initiated active hypometabolism. *砂川 玄志郎(1) 1. 理化学研究所 生命機能科学研究センター *Genshiro A. Sunagawa(1) 1. RIKEN BDR Keyword: hibernation, QIH, torpor, medicine Hibernation is a regulated hypometabolism. Animals lower the basal metabolic rate and exhibit low body temperature as a consequence. How the peripheral tissues tolerate low metabolism during hibernation remains unanswered. When peripheral tissues face a prolonged shortage of oxygen for any reason, the tissue will suffer from hypoxic damage. Shocks and respiratory failures are good examples, although they have distinct etiologies. Modern medicine attempts to recover the damaged oxygen supply when patients suffer from a mismatch of oxygen demand and supply. Hibernators also face a shortage of food during winter, making it impossible for the animal to meet the energy demand at the peripheral tissues. They overcome such food shortages by reducing their basal metabolic rate rather than hunting food in the winter. Suppose critically ill patients can reduce their metabolic rate as hibernators, and the patient can survive longer than before. This will provide a novel choice for primary care with critically ill patients. This talk will show that QIH (Q neurons–Induced Hypometabolism) can delay acute disease progression. I would like to discuss the possibility of acute disease management via brain-initiated active hypometabolism.