Role of delta-opioid receptors in biological processes.

Agonists at the delta-opioid receptor were initially investigated as potential analgesic agents that may lack the undesired effects (respiratory depression, constipation, dependence) of mu-opioid agonists such as morphine. These studies have, however, uncovered that the delta-opioid system is involved in many biological processes, and thus delta-opioid-based medications have great therapeutic potential for the treatment of a wide variety of disorders.