Simultaneous changes in hypothalamic catecholamine levels and plasma corticosterone concentration in the rat after acute morphine and during tolerance.

TL;DR: Results from all variables characterize intermittent morphine injections as a chronic stressor, in contrast to constant treatment, injected morphine probably allows some withdrawal during each 12 h interval, causing repeated stress.

TL;DR: The sixteenth installment of the annual review of research concerning the opiate system is presented, restricted to papers published during 1993 that concern the behavioral effects of the endogenous opiate peptides, and does not include papers dealing only with their analgesic properties.

TL;DR: The results show an interaction between opioid-receptors and alpha 2-adrenoceptors in the hypothalamus, and suggest that mechanisms other than hyperactivity of NA neurons contribute to the HPA axis hyperactivity during the opiate withdrawal.

TL;DR: It is demonstrated that prenatal morphine exposure alters the ACTH and CORT responses to stress but not the sensitivity of negative feedback of glucocorticoids.

TL;DR: The responsiveness and physiological consequences of activation of these two systems are so inter-twined as to have generated the hypothesis that activation of the HPA is evoked by sympathoadrenomedullary activation.

TL;DR: In tolerant rats, the rate of incorporation of carbon-14 into dopamine and into norepinephrine in these areas is more than twice that in animals that have received only one injection of morphine.

TL;DR: The results suggest the opioid peptides and their receptors play a major role in the regulation of HPA function.

TL;DR: The results indicate that morphine and the enkephalins evoke hypothalamo-pituitary-adrenocortical activity by stimulating specific receptors in the hypothalamus and raise the possibility that opioid peptides and their receptors are physiologically important in the control of the secretion of CRF.