Urinary Epinephrine and Norepinephrine Responses to 72-Hr. Avoidance Sessions in the Monkey

Abstract

Marked elevations in urinary epinephrine levels occur in response to 72-hr. conditioned avoidance sessions in the monkey. The response is relatively rapid and brief, reaching a peak on the first avoidance day, declining on the second and third avoidance days, and returning to baseline levels immediately on the first recovery day. In some instances epinephrine levels fell substantially below baseline values during the recovery period. Smaller but significant elevations in urinary norepinephrine levels occur during the avoidance session, with considerably larger elevations often ensuing for many days in the recovery period-a response phase apparently not previously reported. These epinephrine and norepinephrine changes, while substantial, do not appear to represent maximal sympathetic-adrenal medullary responses nor was any evidence of exhaustion of this system observed. Repetition of the 72-hr. avoidance experience is associated generally with both diminishing basal urinary catecholamine levels and urinary catecholamine response to avoidance. Significant responses persisted, however, through at least six successive sessions at monthly intervals. Substantial individual differences were observed between monkeys with respect to mean urinary epinephrine and norepinephrine response to avoidance.