Food access modifies GnIH, but not CRH, cell number in the hypothalamus in a female songbird

Abstract

Food deprivation or restriction causes animals to mount a stereotypical behavioral and physiological response that involves overall increases in activity, elevated glucocorticoid production, and (often) inhibition of the reproductive system. Although there is increasing evidence that these responses can differ in their degree or covariation between the sexes, most studies to-date on food restriction/deprivation have focused on male songbirds. We therefore aimed to characterize the behavioral, physiological, and neuroendocrine response to acute food deprivation in a female songbird using a nomadic species, the zebra finch. We quantified behavior during a 6.5 h food deprivation and then measured physiological and neuroendocrine responses of female birds at the 6.5 h timepoint. Within 1 h of acute food deprivation, female zebra finches increased foraging behaviors, and after 6.5 h of food deprivation, females lost 5% of their body mass, on average. Change in body mass was positively associated with elevated corticosterone and (contrary to findings in male zebra finches) negatively related to the number of gonadotropin inhibitory hormone-immunoreactive cells in the hypothalamus. However, there was no effect of food deprivation on corticotropin releasing hormone-immunoreactive cells in the hypothalamus. There was also no relationship between corticotropin releasing hormone-immunoreactive cell number and circulating corticosterone. Our results are consistent with the hypothesis that neuroendocrine responses to food deprivation differ between male and female songbirds. Future studies should work to incorporate sex comparisons to evaluate sex-specific neuroendocrine responses to acute stress.