SINGLE AND REPEATED ENVIRONMENTAL-STRESS - EFFECT ON PLASMA OXYTOCIN,CORTICOSTERONE, CATECHOLAMINES, AND BEHAVIOR

Rat studies were done to further characterize an environmental model o f stress designated shaker stress (SS). Plasma oxytocin (OT), corticos terone (CS), norepinephrine (NE), and epinephrine (E) were measured be fore and after 5 or 30 min of SS applied one time or applied 10 times over a 2-week period. The major findings were partial adaptation of pl asma E within 30 min of acute SS, adaptation of plasma CS baselines bu t not responses to chronic SS, and complete adaptation of plasma OT re sponses to chronic SS. Poststress behavior during chronic SS was affec ted in the following ways: freezing time habituated, defecation and re arings increased, and grooming and teeth chattering remained relativel y constant. The results show that SS produces consistent patterns of h ormonal and behavioral responses; some aspects of the patterns are sim ilar to those elicited by other environmental stresses, whereas some a spects are unique to SS. We conclude that rats do not adapt to repeate d SS but rather that most hormonal and behavioral defense mechanisms a re renewable on a daily basis. (C) 1997 Elsevier Science Inc.