High heritable variation of egg testosterone (T) concentrations has been found in several avian species indicating the evolutionary relevance for maternal T-dependent traits in offspring. However, underlying mechanisms of this genetic variation and potential consequences for female reproductive physiology are not understood. Therefore, we analysed pituitary and gonadal responsiveness during the ovulatory cycle and after a single gonadotropin releasing hormone (GnRH) stimulation in females from two lines of Japanese quail divergently selected for yolk T concentrations. Luteinizing hormone (LH), T and estradiol levels were measured in the circulation of laying females. Time of expected ovulation was comparable in both lines. The temporal pattern of plasma LH levels during the ovulatory cycle significantly differed between lines showing the maximum 3.5 and 0.5 hours before ovulation in high (HET) and low (LET) egg T females, respectively. Moreover, HET females displayed higher LH levels 6.5 and 3.5 hours before ovulation than LET quails, while no line differences were found around the time of expected ovulation. Preovulatory peaks of plasma T and estradiol concentrations were observed between 6.5 and 3.5 hours prior ovulation in both lines. HET as compared to LET quails showed increased plasma T and a tendency to elevated estradiol concentrations 6.5 hours before ovulation. Pituitary responsiveness to GnRH stimulation did not differ between lines. In conclusion, our results demonstrate that genetically programmed high yolk T deposition is associated with the increased preovulatory peak of LH and T in the circulation implying potential consequences for functioning of female reproductive system and behaviour. Supported by grants VEGA 1/0686/15 and APVV 0047-10 to MO, MZ and grant funding from the BBSRC to SLM.
|Conference||Eleventh International Symposium on Avian Endocrinology|
|Period||11/10/16 → 14/10/16|