Meeting Abstract

3.1  Saturday, Jan. 4 08:00  Aggressive responses to food insecurity: the search for novel steroid-peptide interactions FOKIDIS, HB*; PRIOR, NH; MA, CC; GRADANDOS-SAMAYOA, J; TAVES, MD; ADOMAT, HA; GUNS, ES; SALDANHA, CJ; SOMA , KK; Rollins College; Univ. of British Columbia; Univ. of British Columbia; Univ. of British Columbia; Univ. of British Columbia; Vancouver Prostate Centre; Vancouver Prostate Centre; American Univ.; Univ. of British Columbia hfokidis@rollins.edu

Aggression enables individuals to access limited resources. Most research has focused on the regulation of male breeding aggression where circulating testosterone (T) is converted to estradiol (E₂) by aromatase (AROM) within the brain to act on receptors in behavioral circuits. Food insecurity is common in nature and can promote aggression, but is percieved as a stressor, stimulating corticosterone (CORT) secretion in birds. Higher CORT lowers circulating T, thus suggesting aggression during food insecurity is mediated by another, as yet unknown, mechanism. Using novel behavioral tests we explored how food insecurity impacts aggression in both gregarious and territorial birds. In zebra finches, fasting increased aggressive interactions between individuals competing for a food source, while both decreasing T and elevating levels of CORT and the prohormone, dehydroepiandrosterone (DHEA). Circulating DHEA can be metabolized to E₂ within the brain to maintain aggression. In microdissected brain tissue, fasting increased E₂ content within the vertebrate social behavior network. In territorial song sparrows, fasting increased aggression in a resident-intruder test and altered steroid profiles as determined using liquid chromatography – mass spectrometry. To identify neuroendocrine links between energy and behavior pathways within the social behavior network, we investigated immunoreactivity for neuropeptide-Y (NPY) and orexin (two central regulators of food intake) and AROM in response to fasting and aggressive encounters over food. We propose fasting may promote DHEA secretion and its neural conversion to E₂ where it may interact to promote aggression during food insecurity.