Institute of Biodiversity, Animal Health & Comparative Medicine, University of Glasgow, Glasgow, UK.
J Exp Zool A Ecol Integr Physiol. 2022 Dec;337(9-10):919-938. doi: 10.1002/jez.2634. Epub 2022 Jun 10.
In most animals, annual rhythms in environmental cues and internal programs regulate seasonal physiology and behavior. Prolactin, an evolutionarily ancient hormone, serves as a molecular correlate of seasonal timing in most species. Prolactin is highly pleiotropic with a wide variety of well-documented physiological effects; in a seasonal context prolactin is known to regulate annual changes in pelage and molt. While short-term homeostatic variation of prolactin secretion is under the control of the hypothalamus, long-term seasonal rhythms of prolactin are programmed by endogenous timers that reside in the pituitary gland. The molecular basis of these rhythms is generally understood to be melatonin dependent in mammals. Prolactin rhythmicity persists for several years in many species, in the absence of hypothalamic signaling. Such evidence in mammals has supported the hypothesis that seasonal rhythms in prolactin derive from an endogenous timer within the pituitary gland that is entrained by external photoperiod. In this review, we describe the conserved nature of prolactin signaling in birds and mammals and highlight its role in regulating multiple diverse physiological systems. The review will cover the current understanding of the molecular control of prolactin seasonality and propose a mechanism by which long-term rhythms may be generated in amniotes.
在大多数动物中，环境线索和内部程序的年度节律调节季节性生理和行为。催乳素是一种古老的激素，作为大多数物种季节性时间的分子相关物。催乳素具有高度的多效性，具有广泛的、有充分记录的生理效应；在季节性背景下，催乳素已知可调节皮毛和蜕皮的年度变化。虽然催乳素分泌的短期体内平衡变化受下丘脑控制，但催乳素的长期季节性节律由位于垂体中的内源性计时器编程。这些节律的分子基础通常被认为在哺乳动物中依赖于褪黑素。在许多物种中，即使没有下丘脑信号，催乳素的节律性也会持续数年。哺乳动物中的这种证据支持了这样一种假设，即催乳素的季节性节律来自于垂体内部的内源性计时器，它受外部光周期的调节。在这篇综述中，我们描述了催乳素信号在鸟类和哺乳动物中的保守性质，并强调了它在调节多种不同生理系统中的作用。该综述将涵盖对催乳素季节性的分子控制的当前理解，并提出一个可以在羊膜动物中产生长期节律的机制。
