Ohta M, Kadota C, Konishi H
Department of Veterinary Physiology, College of Agriculture, University of Osaka Prefecture, Japan.
Biol Reprod. 1989 May;40(5):935-41. doi: 10.1095/biolreprod40.5.935.
To estimate whether melatonin is involved in gonadal activity in the male quail, the dynamics of plasma melatonin at an early stage of the photoperiodic response were investigated. Nocturnal levels of melatonin were manipulated by treatment with anti-melatonin (anti-M). By means of 4 additional hours of photic stimulation of the brain (provided by a red light-emitting diode inserted through the back of the head) after the environmental lights (8L:16D, lights-on, 1000 h) were turned off, the elevation of levels of melatonin after lights-off was significantly suppressed on Days 1 and 2 (p less than 0.01); after 5 days of brain-lighting, gonadal growth first became noticeable. However, 4 h of brain-lighting before lights-on elicited no change in levels of melatonin or in gonadal growth. The injections of anti-M just before lights-off (at 1800 h) for the first 3 days caused significant gonadal growth (p less than 0.01), whereas injections at 2200, 0200, or 0600 h were without effect. In addition, 4 h of brain-lighting before lights-on became gonadostimulatory (p less than 0.01) when it was accompanied by the injection of anti-M at 1800 h, but remained without effect when anti-M was injected at 0600 h. These results suggest that melatonin is involved in the initial stage of photoperiodism in birds, and the timing of suppression of the elevation of melatonin levels is critical in gonadal development.
为了评估褪黑素是否参与雄性鹌鹑的性腺活动，研究了光周期反应早期血浆褪黑素的动态变化。通过用抗褪黑素（anti-M）处理来调控夜间褪黑素水平。在环境光（8小时光照：16小时黑暗，开灯时间为1000时）关闭后，通过插入头部后方的红色发光二极管对大脑进行额外4小时的光刺激，结果发现，关灯后第1天和第2天，褪黑素水平的升高受到显著抑制（p<0.01）；大脑光照5天后，性腺生长开始明显可见。然而，开灯前4小时的大脑光照并未引起褪黑素水平或性腺生长的变化。在最初3天的关灯前（1800时）注射anti-M可导致性腺显著生长（p<0.01），而在2200时、0200时或0600时注射则无效。此外，开灯前4小时的大脑光照在1800时注射anti-M时具有性腺刺激作用（p<0.01），但在0600时注射anti-M时则仍然无效。这些结果表明，褪黑素参与鸟类光周期现象的初始阶段，褪黑素水平升高的抑制时间对性腺发育至关重要。
