Epinephrine, norepinephrine, dopamine and serotonin: differential effects of acute and chronic stress on regional brain amines.

Following acute cold swim stress, hypothalamic epinephrine concentrations were markedly lowered and remained decreased for 24 h, while norepinephrine concentrations were decreased, but returned to baseline within 14 h. With oscillation stress repeated daily for 21 days, hypothalamic norepinephrine, hypothalamic epinephrine, and hippocampal norepinephrine turnover were decreased and absolute concentrations were increased. Repeated stress had little effect on serotonin, dopamine or their metabolites. These results suggest that hypothalamic epinephrine concentration and turnover are particularly responsive to acute and chronic stress. The decreased epinephrine and norepinephrine turnover under chronic stress may be responsible in part for the behavioral and endocrine changes observed in chronically stressed rats.