Meeting Abstract

P1.91  Monday, Jan. 4  Effects of dietary restriction on the development of avian endocrine axes: Hormone receptor mRNA expression and response to GnRH challenges by captive rhinoceros auklet chicks (Cerorhinca monocerata) BENOWITZ-FREDERICKS, M.*; LI, W. W.; KITAYSKY, A. S.; Bucknell University; Bucknell University; University of Alaska Fairbanks zmbf001@bucknell.edu

Food availability during chick-rearing can be highly variable for seabirds. Chicks often experience food shortages, and the morphological and endocrine consequences of food restriction (particularly growth rates and circulating glucocorticoids) have been well documented in free-living and captive chicks. In this study, we assessed the effects of post-hatch food restriction on the expression of hormone receptor mRNA (androgen receptor, glucoccorticoid receptor, and IGF-1 receptor) in brain and muscle, and on the response to GnRH challenges in captive rhinoceros auklets (Cerorhinca monocerata ). Food restriction did not affect receptor mRNA expression, but it generated a larger increase in estradiol in response to handling (independent of GnRH treatment). mRNA expression was better explained by size and mass at hatching than treatment, suggesting that these aspects of endocrine physiology are determined prior to hatching, and not affected by post-hatching food intake