Immunoregulatory Activity of Endogenous Opioids

Abstract

This chapter suggests that endogenous opiates can modulate immune functions, not only as regulation by the nervous/neuroendocrine systems, but as autoregulatory factors derived from lymphoid cells themselves. It postulates that leukocytes may serve as an extrapituitary source of endorphin (END)-like molecules that are produced in response to bacterial endotoxin. The chapter determines whether human mononuclear cells or mouse spleen cells were able to synthesize immunoreactive-END in vitro in response to lipopolysaccharide. The opioid peptides have heterogenous actions depending in part upon the target cell type as well as the concentration of the effector. The endogenous opiates function as neurotransmitters, defined by their release from neurons and subsequent actions on neurons. Endogenous opioids have been implicated as possible mediators of some of the pathophysiological changes induced during endotoxic shock and Gram-negative sepsis. This implication was a result of the ability of the potent opiate antagonist, naloxone, to alleviate endotoxin-induced hypotension and changes in body temperature by apparently blocking the effector molecule.