OPIOID AND OPIATE IMMUNOREGULATORY PROCESSES

The discovery of the ability of the nervous system to communicate thro ugh ''public'' circuits with other systems of the body is attributed t o Ernst and Berta Scharrer, who described the neurosecretory process i n 1928. Indeed, the immune system has been identified as another impor tant neuroendocrine target tissue. Opioid peptides are involved in thi s communication (i.e., neuroimmune) and with that of autoimmunoregulat ion (communication between immunocytes). The significance of opioid ne uropeptide involvement with the immune system is ascertained from the presence of novel delta, mu, and kappa receptors on inflammatory cells that result in modulation of cellular activity after activation, as w ell as the presence of specific enzymatic degradation and regulation p rocesses. In contrast to the relatively uniform antinociceptive action of opiate and opioid signal molecules in neural tissues, the presence of naturally occurring morphine in plasma and a novel mu(3) opiate-sp ecific receptor on inflammatory cells adds to the growing knowledge th at opioid and opiate signal molecules may have antagonistic actions in select tissues. In examining various disorders (e.g., human immunodef iciency virus, substance abuse, parasitism, and the diffuse inflammato ry response associated with surgery) evidence has also been found for the involvement of opiate/opioid signaling in prominent mechanisms. In addition, the presence of similar mechanisms in man and organisms 500 million years divergent in evolution bespeaks the importance of this family of signal molecules. The present review provides an overview of recent advances in the field of opiate and opioid immunoregulatory pr ocesses and speculates as to their significance in diverse biological systems.