EFFECT OF STRESS ON HYPOTHALAMIC INSULIN IN RATS

Four experiments examined the effects of stress on hypothalamic insulin and plasma hormones in rats. Two hours daily of immobilization (IM) stress for 2 and 4 days resulted in an increase in hypothalamic insulin. In contrast, 15 min of daily IM over 13 days or 48 h of continuous signalled shock avoidance did not alter hypothalamic insulin. These findings are interpreted to indicate that changes in hypothalamic insulin are part of the stress response. Possible reasons for the different effects of time and paradigm on the hypothalamic insulin responses to stress are discussed. Plasma insulin and glucose levels were not responsive to any of the stressors. Brief acute stress caused increases in the stress-responsive hormones ACTH, corticosterone, and prolactin, as expected, and these responses attenuated or disappeared with repeated or longer stress exposures.