Blache D, Zhang S, Martin G B
School of Animal Biology, Faculty of Natural and Agricultural Sciences, University of Western Australia, Crawley 6009, Australia.
Reprod Suppl. 2003;61:387-402.
Animals adjust the time of year that they reproduce through their ability to perceive and respond to critical aspects of their environment, such as photoperiod, nutrition or the socio-sexual milieu, and their genotype determines the degree of response to each stimulus. Ultimately, information from environmental cues filters through to the GnRH neurones in the brain which are the primary regulator of fertility. Each of these cues has been studied in isolation and the mechanisms by which they affect GnRH secretion are now better, if not fully, understood. In the field, the brain centres that control GnRH must integrate information from all cues at any given time before 'formulating a reproductive decision'. In this review, the effect of this integration is illustrated by showing how the acute GnRH response to a nutritional signal can be modulated by genotype, photoperiod and social cues, to the point of being completely blocked under some circumstances. Candidate pathways that may mediate these modulatory effects at both the whole body and brain have been proposed, although none of these pathways are confirmed and some have not yet been studied. As a guide for further research, we propose a working model that integrates the inputs and explains the interactions between them.
动物通过感知和响应环境的关键因素（如光周期、营养或社会性别环境）来调整繁殖的年份时间，其基因型决定了对每种刺激的反应程度。最终，来自环境线索的信息会传递到大脑中的促性腺激素释放激素（GnRH）神经元，这些神经元是生育能力的主要调节者。这些线索中的每一个都已被单独研究，并且它们影响GnRH分泌的机制现在即使没有完全理解，也有了更好的理解。在实际情况中，控制GnRH的脑中枢在“做出繁殖决定”之前，必须在任何给定时间整合来自所有线索的信息。在这篇综述中，通过展示对营养信号的急性GnRH反应如何受到基因型、光周期和社会线索的调节，直至在某些情况下被完全阻断，来说明这种整合的效果。已经提出了可能在全身和大脑中介导这些调节作用的候选途径，尽管这些途径都未得到证实，有些甚至尚未被研究。作为进一步研究的指南，我们提出了一个整合输入并解释它们之间相互作用的工作模型。
