gnrh - a missing link between testosterone concentrations in yolk and plasma and its intergenerational effects促,蛋黄和血浆中睾酮浓度之间的缺失环节及其代际效应.pdfVIP

GnRH - a Missing Link between Testosterone Concentrations in Yolk and Plasma and Its Intergenerational Effects ¨ 1 2 1 1 Wendt Muller *, Ton G. G. Groothuis , Vivian C. Goerlich , Marcel Eens 1 Department of Biology-Ethology, University of Antwerp, Antwerp, Belgium, 2 Behavioural Biology, University of Groningen, Groningen, The Netherlands Abstract Despite the strong interest in hormone-mediated maternal effects two key questions concerning their mechanisms are as yet unanswered: First, whether the deposition of hormones in the egg yolk is coupled with the levels of these hormones in the maternal circulation, and second, whether epigenetic changes as induced by embryonic exposure to maternal yolk hormones impinge on yolk hormone deposition at adulthood. We investigated the responsiveness to gonadotropin- releasing hormone (GnRH) in female canaries whose embryonic exposure to yolk testosterone had been manipulated. This enabled us to study to what extent GnRH interlinks testosterone concentrations in female circulation and egg yolk as well as the intergenerational potential of hormone-mediated maternal effects. As expected, canary females responded to GnRH with a rise in plasma testosterone. The GnRH-responsiveness was positively correlated with the yolk testosterone content. Factors stimulating the release of GnRH will, therefore, lead to an increase of testosterone in both plasma and egg, posing a potential constraint on the yolk hormone deposition due to testosterone related trade-offs within the laying female. Exposure to elevated yolk testosterone levels as embryo reduced the GnRH-responsiveness in adulthood, potentially limiting environmental influences on yolk testosterone deposition, but the concentrations