Study of the molecular mechanisms involved in GnIH control of reporduction in chickens

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As for most vertebrates, reproduction in birds is controlled by the hypothalamo-pituitary-gonadal axis and each component secretes specific factors and hormones. Until recently, it was believed that this axis was exclusively under stimulatory control with an increase in day length stimulating the release of gonadotropin releasing hormone (GnRH) from the hypothalamus, followed by luteinizing hormone and follicle stimulating hormone secretion by the pituitary gland. However, recently the discovery of a novel inhibitory hypothalamic peptide (gonadotropin inhibitory hormone or GnIH) challenged this existing dogma. Nonetheless, the exact molecular mechanisms involved in GnIH action are still unknown and, the proposed research aims at elucidating its effects at every level of the axis. Within the hypothalamus, I propose to determine the factors controlling GnIH expression around sexual maturation. At the pituitary level, I will determine how gonadotropes integrate and react to stimulatory (via GnRH) and inhibitory (via GnIH) inputs. Furthermore, the effect of this dual control on pituitary function will be clarified. At a gonadal level, I propose to examine possible autocrine/paracrine actions of GnIH on testicular development and function. Based on data we accumulated over the years, I have developed a model summarizing molecular events occurring around sexual maturations in chickens. Results from this study will help verify this model, and could be extrapolated to improve reproduction efficiency in poultry farming as well as designing new therapeutic strategies to control reproduction in wild and pet birds.