Buijs R M, Kalsbeek A, van der Woude T P, van Heerikhuize J J, Shinn S
Neurosciences Loeb Medical Research Institute, Ottawa Civic Hospital, Ontario, Canada.
Am J Physiol. 1993 Jun;264(6 Pt 2):R1186-92. doi: 10.1152/ajpregu.1993.264.6.R1186.
The diurnal rhythm of corticosteroid secretion is controlled by the suprachiasmatic nucleus (SCN). In rats, plasma corticosteroid levels rise just before the onset of the activity period during the dark phase. Our previous results indicated that vasopressin as a neurotransmitter from the SCN inhibited corticosteroid secretion in the area of the paraventricular/dorsomedial nucleus of the hypothalamus. We hypothesized that during the day the SCN may serve as an inhibitory system for corticosteroid secretion. To investigate this possibility, intact and SCN-lesioned animals were exposed to mild stress in the morning and evening and their plasma corticosteroid levels were monitored. The results indicate that SCN-lesioned animals have higher morning corticosteroid levels and respond both in the morning and evening with higher corticosteroid levels after stress than do intact control animals. We conclude, therefore, that these results indicate an inhibitory role of the SCN on corticosteroid secretion. The apparent discrepancy with the reported stimulatory role of the SCN on adrenocorticotropic hormone secretion is discussed.
皮质类固醇分泌的昼夜节律受视交叉上核（SCN）控制。在大鼠中，血浆皮质类固醇水平在黑暗期活动期开始前升高。我们之前的结果表明，作为来自SCN的神经递质的血管加压素在下丘脑室旁/背内侧核区域抑制皮质类固醇分泌。我们假设在白天，SCN可能作为皮质类固醇分泌的抑制系统。为了研究这种可能性，将完整的和SCN损伤的动物在早晨和晚上暴露于轻度应激，并监测它们的血浆皮质类固醇水平。结果表明，与完整的对照动物相比，SCN损伤的动物早晨皮质类固醇水平更高，并且在应激后早晨和晚上的皮质类固醇水平反应更高。因此，我们得出结论，这些结果表明SCN对皮质类固醇分泌具有抑制作用。文中讨论了与报道的SCN对促肾上腺皮质激素分泌的刺激作用明显不符的情况。
