Endocrine responses to electric shock and avoidance conditioning in the rhesus monkey: cortisol and growth hormone

(1) Rhesus monkeys with indwelling atrial catheters were acclimatized to continued restraint in chairs inside isolation cubicles. (2) Cortisol and growth hormone were measured in plasma samples while animals were at rest, receiving electric shocks or being trained to successfully avoid electric shocks by pressing a lever while exposed to a warning signal. (3) Following chairing, GH levels were low from the start. (4) In contrast, cortisol levels showed an initial elevation. (5) Electric shocks and shaping were powerful stimuli to secretion of both cortisol and GH. (6) In confirmation of previous work, it was found that once animals were well trained and were able to avoid most shocks by pressing a lever, there was no activation of either hormone. (7) These results provide additional evidence that different classes of stress situations produce different patterns of hormone response.