18.2 Monday, Jan. 4 How can stress affect the neural control of reproduction? An examination of gonadotropin inhibitory hormone (GnIH) and glucocorticoid receptors (GR) in songbirds CALISI, R.M.*; PERFITO, M.N.; BENTLEY, G.E.; Univ. of California, Berkeley; Max Planck Institute for Ornithology, Univ. of California, Berkeley; Univ. of California, Berkeley, email@example.com
Stress can have an inhibitory effect on reproduction in many organisms. However, the direct links between stress physiology, sexual behavior and reproduction are not very well understood. Generally in vertebrates, the adrenal glands produce the glucocorticoids cortisol and corticosterone in response to stressors. The neuropeptide gonadotropin inhibitory hormone (GnIH) inhibits reproduction via its action on gonadotropin-releasing hormone (GnRH) in the hypothalamus, on luteinizing hormone in the pituitary, and on testosterone and estradiol in the gonad. We recently reported that the hypothalamic content of GnIH peptide increases in house sparrows during times of stress at the beginning of the breeding season, demonstrating a mechanism by which reproduction could be delayed or disrupted in response to environmental stimuli. Using an avian model, we examined how different types of stress could affect the hypothalamic control of reproduction and sexual behavior. Specifically, we investigated the expression of hypothalamic glucocorticoid receptors (GR) and hypothalamic GnIH. We are the first to report the co-localization of GR mRNA within GnIH-producing cells in birds. This co-localization provides the neuroanatomical infrastructure for glucocorticoids to influence GnIH synthesis and release directly. In addition, we compared GnIH content and GR expression in European starlings experiencing intense nest site competition. These data represent the first indicating effects of social environment on GnIH.