Fischman A J, Kastin A J, Graf M V, Moldow R L
Department of Biology, Seton Hall University, S. Orange, N.J.
Neuroendocrinology. 1988 Apr;47(4):309-16. doi: 10.1159/000124930.
The effect of constant light and constant dark on the circadian rhythm of the concentrations of hypothalamic corticotropin-releasing-factor-like immunoreactivity (CRF-LI), plasma ACTH, and corticosterone was investigated. Groups of rats were maintained under normal light-dark, constant light, or constant dark conditions for 10 days. Rats were then killed over a 24-hour time period and hypothalamic CRF-LI, plasma ACTH, and corticosterone concentrations were determined by radioimmunoassay. Under normal light-dark conditions, troughs in hypothalamic CRF-LI concentrations coincided with peaks in plasma ACTH and corticosterone concentrations. In rats housed under constant dark conditions for 10 days, higher hypothalamic CRF-LI concentrations were detected at 20.00, 24.00 and 04.00 h than at 08.00, 12.00 and 16.00 h. These relatively high hypothalamic CRF-LI concentrations coincided with relatively low plasma ACTH concentrations. The amplitude of plasma ACTH concentrations was markedly attenuated compared to levels of rats housed under normal light-dark conditions. The rats exposed to constant dark continued to demonstrate higher plasma corticosterone concentrations post meridiem than ante meridiem. The peak in plasma corticosterone coincided with the peak in plasma ACTH concentrations; however, the amplitude was normal. In rats maintained in constant light for 10 days, a decrease in hypothalamic CRF-LI concentrations at 20.00 h coincided with a peak in plasma ACTH. The peak in plasma ACTH concentrations was not associated with a peak in plasma corticosterone concentrations. The rhythm of plasma corticosterone concentrations was dramatically attenuated and phase-shifted. Together, these findings indicate that alterations of normal light-dark conditions result in changes in the circadian variation in hypothalamic CRF-LI, plasma ACTH, and corticosterone concentrations.(ABSTRACT TRUNCATED AT 250 WORDS)
研究了持续光照和持续黑暗对下丘脑促肾上腺皮质激素释放因子样免疫反应性（CRF-LI）、血浆促肾上腺皮质激素（ACTH）和皮质酮浓度昼夜节律的影响。将大鼠分组，分别置于正常昼夜、持续光照或持续黑暗条件下饲养10天。然后在24小时内处死大鼠，通过放射免疫分析法测定下丘脑CRF-LI、血浆ACTH和皮质酮浓度。在正常昼夜条件下，下丘脑CRF-LI浓度的低谷与血浆ACTH和皮质酮浓度的峰值相吻合。在持续黑暗条件下饲养10天的大鼠中，在20:00、24:00和04:00时检测到的下丘脑CRF-LI浓度高于08:00、12:00和16:00时。这些相对较高的下丘脑CRF-LI浓度与相对较低的血浆ACTH浓度相吻合。与正常昼夜条件下饲养的大鼠相比，血浆ACTH浓度的振幅明显减弱。暴露于持续黑暗的大鼠午后血浆皮质酮浓度仍高于午前。血浆皮质酮的峰值与血浆ACTH浓度的峰值相吻合；然而，振幅正常。在持续光照10天的大鼠中，20:00时下丘脑CRF-LI浓度的降低与血浆ACTH的峰值相吻合。血浆ACTH浓度的峰值与血浆皮质酮浓度的峰值无关。血浆皮质酮浓度的节律明显减弱并发生了相位改变。总之，这些发现表明正常昼夜条件的改变会导致下丘脑CRF-LI、血浆ACTH和皮质酮浓度昼夜变化的改变。（摘要截短至25０字）
