Edmonds K E, Stetson M H
Physiology and Anatomy Section, School of Life and Health Sciences, University of Delaware, Newark 19716.
J Pineal Res. 1994 Sep;17(2):86-93. doi: 10.1111/j.1600-079x.1994.tb00118.x.
Reproduction in rice rats is subject to photoperiodic control and the pineal gland mediates this effect. We examined the effects of the pineal gland hormone melatonin on testicular weight when administered via implants, injections, and infusions. Testicular weight was modified by photoperiod and the size of the melatonin implant. Twenty-millimeter implants suppressed testicular weight in rice rats housed on 12- and 16-hr photoperiods, while those housed on a 14-hr photoperiod were more sensitive to melatonin; in these animals 10- and 20-mm implants inhibited testicular weight. Melatonin implants also prevented rice rats from responding to a change in photoperiod with the appropriate alteration of testicular growth. Melatonin injections inhibited testicular growth when administered before lights out on LD 14:10, but not on LD 16:8. Morning injections had no effect on either photoperiod. Finally, 12-hr duration melatonin infusions inhibited testicular growth in pinealectomized rice rats on LD 16:8, while 6-hr duration infusions were without effect. These data show that the pineal, through the secretion of melatonin, is a phototransducing organ intimately involved in testicular growth in rice rats.
稻鼠的繁殖受光周期控制，松果体介导这种效应。我们研究了通过植入、注射和输注给予松果体激素褪黑素时对睾丸重量的影响。睾丸重量受光周期和褪黑素植入物大小的影响。20毫米的植入物抑制了处于12小时和16小时光周期的稻鼠的睾丸重量，而处于14小时光周期的稻鼠对褪黑素更敏感；在这些动物中，10毫米和20毫米的植入物抑制了睾丸重量。褪黑素植入物还阻止了稻鼠随着光周期变化而相应改变睾丸生长。在LD 14:10的熄灯前注射褪黑素会抑制睾丸生长，但在LD 16:8时则不会。早晨注射对两种光周期均无影响。最后，持续12小时的褪黑素输注抑制了处于LD 16:8的松果体切除稻鼠的睾丸生长，而持续6小时的输注则没有效果。这些数据表明，松果体通过分泌褪黑素，是一个与稻鼠睾丸生长密切相关的光转导器官。
