Watanabe Sayaka, Wei Fan-Yan, Matsunaga Tomomi, Matsunaga Nanami, Kaitsuka Taku, Tomizawa Kazuhito
Department of Molecular Physiology, Faculty of Life Sciences, Kumamoto University, Kumamoto 860-8556, Japan.
Sci Rep. 2016 May 4;6:25185. doi: 10.1038/srep25185.
Oxytocin (Oxt) is a key neuropeptide that regulates maternal behaviors as well as social behaviors in mammals. Interestingly, recent studies have shown that the impairment of Oxt signaling is associated with the disturbance of metabolic homeostasis, resulting in obesity and diabetes. However, the molecular mechanism by which Oxt signaling controls metabolic responses is largely unknown. Here, we report that Oxt signaling attenuates the death of pancreatic beta cells in islets exposed to cytotoxic stresses. The protective effect of Oxt was diminished in islets isolated from oxytocin receptor knockout (Oxtr(-/-)) mice. Oxtr(-/-) mice developed normally, but exhibited impaired insulin secretion and showed glucose intolerance under a high-fat diet. Mechanistically, the deficiency of Oxtr impaired MAPK/ERK-CREB signaling, which exaggerated the endoplasmic reticulum stress response and ultimately increased the death of beta cells in pancreatic islets under stressed conditions. These results reveal that Oxt protects pancreatic beta cells against death caused by metabolic stress, and Oxt signaling may be a potential therapeutic target.
催产素(Oxt)是一种关键的神经肽,可调节哺乳动物的母性行为以及社会行为。有趣的是,最近的研究表明,Oxt信号传导受损与代谢稳态紊乱有关,会导致肥胖和糖尿病。然而,Oxt信号传导控制代谢反应的分子机制在很大程度上尚不清楚。在此,我们报告Oxt信号传导可减轻暴露于细胞毒性应激的胰岛中胰腺β细胞的死亡。在从催产素受体敲除(Oxtr(-/-))小鼠分离的胰岛中,Oxt的保护作用减弱。Oxtr(-/-)小鼠正常发育,但表现出胰岛素分泌受损,并且在高脂饮食下表现出葡萄糖不耐受。从机制上讲,Oxtr的缺乏会损害MAPK/ERK-CREB信号传导,这会加剧内质网应激反应,并最终增加应激条件下胰腺胰岛中β细胞的死亡。这些结果表明,Oxt可保护胰腺β细胞免受代谢应激导致的死亡,并且Oxt信号传导可能是一个潜在的治疗靶点。