Meeting Abstract
Gonadotropin−inhibitory hormone (GnIH) acts to inhibit reproduction at all levels of the hypothalamo−pituitary−gonad (HPG) axis. For example, GnRH neurons express GnIH receptor and decrease firing in response to GnIH application. The anterior pituitary gland of all species studied also expresses GnIH receptor, and GnIH application decreases pituitary gonadotropin synthesis and release. The gonads of all species studied synthesize GnIH and express its receptor, and GnIH can influence gonadal steroid production directly. Exposure to different stressors causes changes in GnIH expression in the hypothalamus and gonads in birds and mammals in vitro and in vivo. GnIH neurons also express glucocorticoid receptor. Thus, GnIH may be involved in stress-induced reproductive inhibition. Here I discuss regulation of GnIH in the avian brain and gonads in response to different stressors and compare our findings to those in mammals. Our data suggest that GnIH responsiveness to cues of stress appears to be conserved across species, but the response of specific tissues and the direction of GnIH regulation can vary. Importantly, the gonads can respond to cues of stress independently from neural input.
