Meeting Abstract
146.4 Monday, Jan. 7 Transitions in avian parental care: a role for hypothalamic gonadotropin inhibitory hormone (GnIH) CALISI, R.M.*; KRAUSE, J.S.; PERFITO, N.; BENTLEY, G.E.; WINGFIELD, J.C.; Univ. of California, Davis; Univ. of California, Davis; Univ. of California, Berkeley; Univ. of California, Berkeley; Univ. of California, Davis beccacalisi@gmail.com
The discovery of GnIH is changing the way we view the regulation of sexual behavior and reproductive function in general. GnIH inhibits gonadotropin synthesis and release in vitro and in vivo in both birds and mammals, resulting in a decrease in circulating sex steroids as well as a decrease in sexual behavior. However, the role of GnIH, if any, during the time of parental care is unknown. The transition from sexual and aggressive behaviors to parental care often involves a decrease in circulating testosterone levels that otherwise can interfere with parental care. Based on preliminary results and the negative effects of GnIH on androgen circulation, we characterized hypothalamic GnIH in male and female European starlings (Sturnus vulgaris) over the parental care phase of the breeding season. We found that GnIH-ir peptide expression changes with the first day of incubation and first day of chick care. We conducted an egg removal experiment to examine how unpredictable events (i.e. nest predation) can affect this relationship. Results revealed that GnIH-ir expression changes in response to egg loss. Thus, changes in GnIH-ir expression during these important transitions in parental care may implicate it in the mediation of such behaviors. Finally, we attempted to block GnIH expression in vivo using a recently discovered RFRP (GnIH mammalian homolog) receptor antagonist, RF9, and found that both systemic and central administration in birds does not alter LH circulation as it does in mammals, nor does systemic administration alter parental behavior, as measured by visits to nests. Thus, while RF9 may serve as a potent RFRP receptor antagonist in mammals, its actions do not appear to function similarly in birds.
