Cassone Vincent M, Bartell Paul A, Earnest Barbara J, Kumar Vinod
Center for Research on Biological Clocks, Department of Biology, Texas A & M University, College Station, TX 77843, USA.
J Biol Rhythms. 2008 Feb;23(1):49-58. doi: 10.1177/0748730407311110.
Avian behavior and physiology are temporally regulated by a complex circadian clock on both a daily and an annual basis. The circadian secretion of the hormone melatonin is a critical component of the regulation of circadian/daily processes in passerine birds, but there is little evidence that the gland regulates annual changes in primary reproductive function. Here it is shown that locomotor rhythms of house sparrows, Passer domesticus, which are made arrhythmic by either pinealectomy or maintenance in constant light, can be synchronized by daily administration of melatonin of different durations to simulate the melatonin profiles indicative of long and short photoperiods. Pinealectomized male sparrows maintained in constant darkness were entrained by both melatonin regimens. In both cases, testes were regressed and the song control nuclei were small. Intact male house sparrows maintained in constant light were also entrained to both melatonin regimens. However, sparrows that received a long duration melatonin cycle exhibited small song control nuclei, while sparrows that received short duration melatonin or no melatonin at all exhibited large song control nuclei. The data indicate that seasonal changes in melatonin duration contribute to the regulation of song control nuclei.
鸟类的行为和生理在日常和年度基础上都受到复杂的昼夜节律时钟的时间调节。激素褪黑素的昼夜分泌是雀形目鸟类昼夜/日常过程调节的关键组成部分，但几乎没有证据表明该腺体调节主要生殖功能的年度变化。在此表明，家麻雀（Passer domesticus）的运动节律，无论是通过松果体切除还是在持续光照下维持而变得无节律，都可以通过每日给予不同持续时间的褪黑素同步，以模拟指示长光周期和短光周期的褪黑素谱。在持续黑暗中饲养的松果体切除雄性麻雀被两种褪黑素方案所诱导。在这两种情况下，睾丸萎缩，鸣唱控制核较小。在持续光照下饲养的完整雄性家麻雀也被两种褪黑素方案所诱导。然而，接受长时间褪黑素周期的麻雀表现出较小的鸣唱控制核，而接受短时间褪黑素或根本不接受褪黑素的麻雀表现出较大的鸣唱控制核。数据表明，褪黑素持续时间的季节性变化有助于调节鸣唱控制核。
