Trends in physiological role of opioids in psychoneuroendocrine-immune network.

Extensive evidence suggests that opioid influences on the immune response are mediated through opioid receptors on the surface of immune cells. In addition, the binding of opioid agonists to centrally located opioid receptors appears also to alter immune activity through interactions with the neuroendocrine and the nervous systems. Finally, other findings summarized in this review provide evidence consistent with the hypothesis that under stressful stimuli, the immune system is altered through the interrelations among the neuroendocrine system, the sympathetic nervous system and central opioidergic pathways