Garcia V, Jouventin P, Mauget R
Centre d'Etudes Biologiques de Chizé/CNRS, Villiers en Bois, France.
Horm Behav. 1996 Sep;30(3):259-65. doi: 10.1006/hbeh.1996.0031.
The King penguin (Aptenodytes patagonicus) has been studied on Possession Island, Crozet Archipelago (46 degrees 25'S-51 degrees 45'E). It is an offshore feeder, but it breeds on land. Its breeding cycle is unusually long (about 14 months). It starts at the beginning of spring, is interrupted during 5 months of winter, and ends in the next spring. Furthermore, it is characterized by a long parental care period, of about 11 months, including the winter interruption. In fact, care given to the egg and the chick is biparental, which supposes that parental behavior includes both parents. Each parent alternates care given to the egg and to the chick on land and foraging bouts at sea. An incubation bout, or a chick care bout, is called a shift. Prolactin is the hypophyseal hormone known to be correlated with incubation and chick care. We studied the mechanism of the maintenance of prolactin during the parental care period in the King penguin, a period which is unusually long. In many species, prolactin secretion has been shown to be stimulated by the presence of eggs and/or chicks, but in the King penguin, prolactin secretion is observed throughout the entire period of parental care, despite the fact that the birds leave the egg and the chick repeatedly and for extended periods of time to feed. Prolactin levels rise significantly at the beginning of courtship; females have significantly higher prolactin levels than males during courtship, copulation, and the period of waiting for egg laying. In both sexes, prolactin levels remain high during incubation and the first part of chick rearing, before winter. Prolactin concentrations decline somewhat during the winter period of minimal parental care, but remain that level in spring when parental care starts again. The level returns to basal value during molt. Prolactin levels rise during the incubation shifts but not over the course of contact with young. Prolactin values remain high in unsuccessful breeders, possibly preventing the birds from relaying, but remain low in immature birds. These data raise questions about how prolactin secretion is controlled in this species. The hypothesis of a programmed secretion of prolactin is advanced.
帝企鹅（阿德利企鹅）已在克罗泽群岛的占有岛（南纬46度25分至东经51度45分）上得到研究。它是一种在近海觅食但在陆地上繁殖的鸟类。其繁殖周期异常漫长（约14个月）。始于春季伊始，在长达5个月的冬季中断，直至次年春季结束。此外，其特点是亲代抚育期较长，约11个月，包括冬季的中断期。实际上，对卵和雏鸟的照料由双亲共同承担，这意味着亲代行为涵盖双亲。双亲各自交替在陆地照料卵和雏鸟以及在海上觅食的时段。一次孵卵时段或雏鸟照料时段被称作一个轮值。催乳素是已知与孵卵和雏鸟照料相关的垂体激素。我们研究了帝企鹅亲代抚育期（此时期异常漫长）催乳素维持分泌的机制。在许多物种中，已表明卵和/或雏鸟的存在会刺激催乳素分泌，但在帝企鹅中，尽管亲鸟会反复且长时间离开卵和雏鸟去觅食，催乳素分泌在整个亲代抚育期都能观察到。求偶开始时催乳素水平显著升高；在求偶、交配以及等待产卵期间，雌性的催乳素水平显著高于雄性。在两性中，催乳素水平在孵卵期间以及冬季来临前雏鸟饲养的第一阶段都保持较高。在亲代照料最少的冬季时段，催乳素浓度有所下降，但在春季亲代照料再次开始时仍维持该水平。在换羽期间，该水平恢复到基础值。催乳素水平在孵卵轮值期间升高，但在与雏鸟接触过程中不会升高。在繁殖失败的亲鸟中，催乳素值仍保持较高，这可能会阻止亲鸟再次繁殖，但在未成熟的鸟类中则保持较低水平。这些数据引发了关于该物种催乳素分泌如何受到控制的问题。提出了催乳素程序性分泌的假说。
