Vacas M I, Cardinali D P
Neurosci Lett. 1979 Dec;15(2-3):259-63. doi: 10.1016/0304-3940(79)96123-8.
A diurnal variation in neuroendocrine sensitivity to melatonin is known to occur in hamsters and rats. The present experiments were carried out to examine the possibility that affinity and/or number of melatonin binding sites in brain could change accordingly at the two times when exogenous melatonin is known to be ineffective or effective to produce neuroendocrine changes, i.e., at 07 : 00 or 20 : 00 h (lights on from 07 : 00 to 21 : 00 h daily). The number of melatonin binding sites in hamster and rat brains was at 20 : 00 h 34--56% higher than at 07 : 00 h, without changing their affinity towards [3H]melatonin (hamster: Kd = 53 nM; rat: Kd = 73--77 nM). These alterations in melatonin receptor density may play a role in daily changes in sensitivity to the exogenous methoxyindole.
已知仓鼠和大鼠的神经内分泌系统对褪黑素的敏感性存在昼夜变化。本实验旨在研究在已知外源性褪黑素无效或有效产生神经内分泌变化的两个时间点，即07:00或20:00时（每天07:00至21:00开灯），大脑中褪黑素结合位点的亲和力和/或数量是否会相应改变。仓鼠和大鼠大脑中褪黑素结合位点的数量在20:00时比07:00时高34%-56%，而它们对[3H]褪黑素的亲和力没有变化（仓鼠：解离常数Kd = 53 nM；大鼠：Kd = 73-77 nM）。褪黑素受体密度的这些变化可能在对外源性甲氧基吲哚敏感性的每日变化中起作用。
