Dissecting the relative contribution of central versus peripheral opioid analgesia: are the analgesic and adverse effects of opioids inseparable?

摘要

In this issue of the journal, an interesting and provocative paper by Khalefa et al. dissects out the relative contribution of peripheral and central opioid receptors to the analgesic effects of systemic opioids (Khalefa et al., 2011). Opioid receptors are expressed at different sites along the neuronal pathway involved in processing nociceptive information, including primary affer-ents, the spinal cord and supraspinal brain structures (Yaksh ahd Rudy, 1976; Snyder and Childers, 1979; Coggeshall et al., 1997; Snyder, 2004). The early studies on the potential sites of action of exogenous opioids focused on central nervous system (CNS) sites, particularly regions in the brain (Kuhar et al., 1973). The subsequent discovery of spinal opioid receptors and the powerful analgesia resulting from intrathecal administration of opioids in rodents (Yaksh and Rudy, 1976) translated into new therapeutic strategies in humans. Intrathecal and epidural administration of opioids is presently widely used clinically for the treatment of acute perioperative pain and the management of certain chronic pain states (Wallace and Yaksh, 2000).