EFFECTS OF CONTROLLABILITY OF STRESS ON HIPPOCAMPAL PHARMACOLOGY

To examine the effect of the controllability of stress on aspects of h ippocampal noradrenergic, opiate, and cholinergic pharmacology, we tra ined rats in a controllability paradigm and assessed [H-3] desmethylim ipramine, [H-3]quinuclidinyl benzilate, or [H-3]naloxone binding in hi ppocampal areas CA1, CA3, and the dentate gyrus with quantitative auto radiography. Rats that could control shock termination were yoked to r ats that could not control termination of equivalent shock; a third gr oup of rats received no shock. When the rats that could terminate shoc k responded at an 85% rate, their brains were removed and sectioned, i ncubated with tritiated Ligands, and exposed to film for an appropriat e period. Quantitative densitometry revealed a 10%-22% decrease in nal oxone binding in CA3 in rats receiving uncontrollable shock; no signif icant changes were observed in rats that could control shock. Thus, th e ability to control shock prevented stress-induced changes in mu opia te receptor binding in area CA3 of the hippocampus.