Laboratory of Animal Physiology, School of Agriculture, Meiji University, Kawasaki, Kanagawa 214-8571, Japan.
Tohoku Medical Megabank Organization, Tohoku University, Sendai, Miyagi 980-8575, Japan.
Neurosci Lett. 2020 Mar 23;722:134814. doi: 10.1016/j.neulet.2020.134814. Epub 2020 Feb 4.
In mammals, the timing of behavior and physiological activity is controlled by the suprachiasmatic nucleus (SCN) in the hypothalamus. Incidentally, secretin is a peptide hormone that promotes digestive activities and regulates water reabsorption. In recent studies, exogenous administration of secretin has been reported to induce secretion of oxytocin in the supraoptic nucleus of the hypothalamus and modulate social behavior. These results indicate that secretin is involved in the neural network that controls social behavior and plays important roles in the central nervous system. In the present study, we investigated the effects of secretin on circadian rhythms, by assessing circadian rhythms during wheel-running behavior in secretin receptor-deficient (Sctr) mice. Male adult wild-type (WT) and Sctr mice were housed in separate cages containing a wheel. Every minute of the wheel-running activity was monitored during the normal light-dark (LD) cycle (12:12 h) and in constant darkness (DD). Significant differences were observed in the free-running period between the WT and Sctr mice. However, no significant differences were observed in the daily wheel-running revolutions between WT and Sctr mice, in the LD and DD conditions. Moreover, the ratio of the daily activity phase to the rest phase (α/ρ) was significantly smaller in Sctr than that in WT mice in the DD condition. Secretin receptors were expressed in the SCN cells. These findings suggest that secretin receptors are involved in the central circadian clock in the SCN and the circadian system in general.
在哺乳动物中，行为和生理活动的时间由下丘脑的视交叉上核（SCN）控制。顺便说一句，促胰液素是一种促进消化活动和调节水重吸收的肽激素。在最近的研究中，已经报道外源性给予促胰液素可诱导下丘脑视上核催产素的分泌，并调节社会行为。这些结果表明，促胰液素参与控制社会行为的神经网络，并在中枢神经系统中发挥重要作用。在本研究中，我们通过评估促胰液素受体缺陷（Sctr）小鼠在轮跑行为期间的昼夜节律，研究了促胰液素对昼夜节律的影响。雄性成年野生型（WT）和 Sctr 小鼠分别饲养在装有轮子的单独笼子中。在正常的明暗（LD）循环（12:12 h）和持续黑暗（DD）中，每一分钟的轮跑活动都进行监测。WT 和 Sctr 小鼠之间的自由运行周期存在显著差异。然而，在 LD 和 DD 条件下，WT 和 Sctr 小鼠的每日轮跑圈数没有显著差异。此外，在 DD 条件下，Sctr 小鼠的每日活动相位与休息相位（α/ρ）的比值明显小于 WT 小鼠。促胰液素受体在 SCN 细胞中表达。这些发现表明，促胰液素受体参与 SCN 中的中央生物钟和一般的昼夜节律系统。
