Leptin modulates oocyte maturation by a central and a direct pathway in zebrafish.

Loss of LEPR function (LOF) in mammals leads to diverse phenotypes including morbid obesity and infertility while zebrafish show relatively minor phenotypes. This however allows the study of LEPR LOF in the absence of the detrimental effects of hyperglycemia or obesity. Here, we show evidence that leptin plays a role in the central as well as peripheral regulation of the hypothalamic-pituitary-gonadal (HPG) axis in zebrafish. Animals with a Lepr LOF show dysregulated pituitary HPG genes as well as evidence that oocytes mature slower and/or exhibit an increased rate of atresia. In culture, Lepr LOF attenuates the effect of 17α-20β-dihydroxy-4 pregnen-3-one in promoting germinal vesicle breakdown (GVBD) and increases the rate of GVBD as well as attenuates the rate of oocyte atresia.