Meeting Abstract

P2.108  Friday, Jan. 4  The effects of chronic stress on the brain: changes in glucocorticoid and mineralocorticoid receptors in European Starlings (Sturnus vulgaris) DICKENS, Molly J.*; CYR, Nicole E; MEDDLE, Simone A.; ROMERO, L. Michael; Tufts University; Wellesley University; University of Edinburgh; Tufts University molly.dickens@tufts.edu

Chronic stress in wild animals affects the secretion of glucocorticoids as well as disrupts the sensitivity of the Hypothalamic-pituitary-adrenal axis. Despite the fact that glucocorticoid (GR) and mineralocorticoid (MR) receptors in the brain also play a role in HPA axis control and are equally important to our understanding of the physiology of the stress response, we know very little about control of neural receptors. We tested the hypothesis that chronic stress, causes alterations to GR and MR expression in the hippocampus and paraventricular nucleus (PVN) regions of the brain. We subjected European Starlings ( Sturnus vulgaris ) to a chronic stress protocol in which rotating daily stressors were presented throughout each day for eighteen days. Control animals were housed under similar conditions to the chronically stressed group but were not subjected to daily rotating stressors. Immediately following the chronic stress period, animals were sacrificed and brains were frozen and later sectioned. Within these sections, in situ hybridizations identified overall receptor distributions and density of GR and MR mRNA expression in the brain. After exposing the slides to autoradiographic emulsion, cell expression was determined by cell counting and silver granule density analysis. Chronically stressed individuals had significantly fewer cells expressing MR receptor RNA in the hippocampus than non-chronically stressed individuals. GR expression did not change in either group indicating that the ratio of MR:GR in the hippocampus is disrupted by chronic stress.