Graf M, Fischman A J, Kastin A J, Moldow R L
Veterans Administration Medical Center, New Orleans, Louisiana.
Am J Physiol. 1988 Sep;255(3 Pt 1):E265-71. doi: 10.1152/ajpendo.1988.255.3.E265.
The diurnal response to ovine corticotropin-releasing factor (CRF-41), arginine vasopressin (AVP), and adrenocorticotropic hormone (ACTH) was studied in rats in which the endogenous release of CRF was blocked by chlorpromazine, morphine sulfate, and pentobarbital sodium. This procedure resulted in a markedly attenuated circadian rhythm at base-line levels of plasma corticosterone and ACTH. Decreased pituitary responsiveness to CRF-41 and AVP at 0400 compared with 1600 was observed. The plasma corticosterone response 30 min after intravenous injection of ovine CRF-41 (0.1 microgram/kg) or AVP (5.0 micrograms/kg) remained nearly constant over the major portion of the 24-h light-dark cycle. However, in the early morning (0400), 2 h before lights on, there was an approximately threefold decrease in response. The time of this decrease in response coincided with the normal decline in the concentrations of plasma corticosterone and ACTH. Rats exposed to constant darkness for 10 days continued to show a significantly greater response to CRF or AVP at 1600 than at 0400. In contrast, rats exposed to constant light for 10 days failed to demonstrate a differential response to CRF or AVP at different times of the day. These results demonstrate that there is a diurnal rhythm in pituitary response to CRF and AVP.
在通过氯丙嗪、硫酸吗啡和戊巴比妥钠阻断促肾上腺皮质激素释放因子（CRF-41）内源性释放的大鼠中，研究了对羊促肾上腺皮质激素释放因子（CRF-41）、精氨酸加压素（AVP）和促肾上腺皮质激素（ACTH）的昼夜反应。该操作导致血浆皮质酮和ACTH基线水平的昼夜节律明显减弱。观察到与16:00相比，垂体在04:00时对CRF-41和AVP的反应性降低。在24小时明暗周期的大部分时间里，静脉注射羊CRF-41（0.1微克/千克）或AVP（5.微克/千克）30分钟后，血浆皮质酮反应基本保持不变。然而，在清晨（04:00），即开灯前2小时，反应性大约降低了三倍。这种反应性降低的时间与血浆皮质酮和ACTH浓度的正常下降时间一致。持续10天暴露于持续黑暗中的大鼠在16:00时对CRF或AVP的反应仍明显大于04:00时。相反，持续10天暴露于持续光照下的大鼠在一天中的不同时间对CRF或AVP未表现出差异反应。这些结果表明，垂体对CRF和AVP的反应存在昼夜节律。
