Meeting Abstract

69.4  Thursday, Jan. 6  Season-dependent modulation of testosterone and estradiol by gonadal neuropeptides MCGUIRE, NM*; KANGAS, K; KOH, A; BENTLEY, GE; Univ. of California, Berkeley; Univ. of California, Berkeley; Univ. of California, Berkeley nicolette@berkeley.edu

Temperate vertebrates time breeding to the appropriate time of year by using day length as a primary predictive cue and availability of food and water, presence of mates/ rivals and occurrence of stressors such as habitat destruction, predation and extreme weather as secondary supplementary cues. Most work has focused on how these cues are perceived and transduced via secretory neurons in the hypothalamus (gonadotropin releasing hormone, gonadotropin inhibitory hormone, kisspeptin). However, here we show that the gonads themselves are capable of responding directly to these cues, in addition to the brain. Using gonadal culture of European starling (Sturnus vulgaris) testes and ovaries, we show that endocrine proxies of environmental cues can significantly modulate testosterone and estradiol secretion. Additionally, we show that sex steroid modulation at the level of the gonad is season-dependent. This modulation appears to be mediated in part by gonadal neuropeptide systems. Our data provide evidence that gonadal steroid release is fine-tuned directly by environmental stimuli in addition to its regulation by the hypothalamo-pituitary-gonad (HPG) axis.