The effects of chronic stress on corticosterone, GH and TSH response to morphine administration.

The effects of a chronic stress model in which several acute stressors were applied on a random basis on corticosterone, growth hormone (GH) and thyroid stimulating hormone (TSH) responses to morphine administration were studied in adult male rats. Chronic stress resulted in lower corticosterone response to the drug. In contrast, GH response to morphine was enhanced in the former animals and TSH response remained unchanged. The physiological role of changes in hormone response to opiates remains to be established, but the present results suggest that central opioid pathways involved in the neuroendocrine control of the anterior pituitary did not respond homogeneously to chronic stress.