Taylor G T, Frechmann T, Royalty J
J Endocrinol. 1986 Sep;110(3):533-7. doi: 10.1677/joe.0.1100533.
The juvenile stage of ontogeny is often characterized as a time of inactivity and quiescence for the immature reproductive system. The principle social behaviour by juveniles of many mammalian species is a rough-and-tumble activity known as play-fighting. An experiment is reported in which play-fighting by male rats was observed after various manipulations of gonadal steroids. Rats were housed in groups and castrated either on day 1 or day 10, times which are respectively during and after the sensitive period for androgen-induced organization of neural tissues in rats. Animals were injected with either 40 micrograms testosterone propionate or vehicle between 21 and 45 days of age, and play-fighting with unoperated, unfamiliar rats was examined. Castration on days 1 and 10 suppressed play-fighting. The behaviours remained suppressed in rats castrated on day 1 and injected with testosterone propionate, but testosterone propionate restored play-fighting to near-normal levels until 35 days of age in rats castrated on day 10. Moreover, gonadally intact juvenile males exposed to the androgen antagonist flutamide play-fought less than intact control males, although their social activity increased appreciably after day 35. It is concluded that the juvenile is not experiencing endocrine quiescence. Behavioural and physiological data suggest a reproductive system which is active, although differently from that in the adult. Hypersensitivity to testosterone and surges of gonadotrophin-releasing factors and LH at 35 days of age may be the events responsible for changes in play-fighting resulting from manipulations of gonadal steroids in juvenile rats.
个体发育的幼年期通常被描述为未成熟生殖系统处于不活跃和静止的时期。许多哺乳动物幼崽的主要社会行为是一种激烈的活动，称为打闹游戏。本文报道了一项实验，观察了在对性腺类固醇进行各种处理后雄性大鼠的打闹游戏行为。将大鼠分组饲养，并在第1天或第10天进行阉割，这两个时间点分别处于大鼠雄激素诱导神经组织组织化的敏感期内和之后。在21至45日龄之间，给动物注射40微克丙酸睾酮或溶剂，并检测其与未手术、不熟悉的大鼠的打闹游戏行为。第1天和第10天阉割均抑制了打闹游戏行为。第1天阉割并注射丙酸睾酮的大鼠的行为仍受到抑制，但丙酸睾酮使第10天阉割的大鼠在35日龄前的打闹游戏行为恢复到接近正常水平。此外，暴露于雄激素拮抗剂氟他胺的性腺完整的幼年雄性大鼠比完整的对照雄性大鼠打闹游戏的次数少，尽管它们在35日龄后社交活动明显增加。研究得出结论，幼年期并非处于内分泌静止状态。行为和生理数据表明，生殖系统是活跃的，尽管与成年期不同。35日龄时对睾酮的超敏反应以及促性腺激素释放因子和促黄体生成素的激增可能是幼年大鼠性腺类固醇处理导致打闹游戏行为变化的原因。
