Meeting Abstract
Exposure to early life stress can alter many aspects of physiology and behavior across all life history stages, with the brain being particularly sensitive. Stress effects are mediated by the glucocorticoid corticosterone (Cort) via intracellular or membrane-bound glucocorticoid receptors (GR). In songbirds, such as the zebra finch (Taeniopygia guttata), song learning and production are controlled by four interconnected song control nuclei. GR are present in two of these nuclei, HVC (proper name) and RA (nucleus robustus arcopallii). Previously we demonstrated that exposure to chronic CORT treatment for over three weeks post-hatch resulted in reduced size of HVC but not RA in brains from juvenile and adult males, as measured in Nissl stained tissue. Experimental birds received a silastic Cort implant on post-hatch day four and controls received either an empty implant or were sham-treated. To further examine the reduction in HVC volume we have quantified the number of neurons in HVC and RA in order to determine if the decrease in HVC size resulted from a decrease in HVC neuron number. We found that males chronically treated with CORT during post-hatch had significantly fewer Nissl-stained neurons in HVC than control birds. There was no difference in RA neuron number between experimental and control birds. Cort-reduction in neuron number may be a specific mechanism by which HVC size and song quality are altered in developmentally stressed birds. Taken together, this suggests a potential role for Cort in mediating adverse effects of developmental stress in adult male zebra finches and highlights the developmental plasticity of the zebra finch brain.
