Mu-opioid receptor (MOR)

The mu-opioid receptor (MOR), encoded by the OPRM1 gene, is a GPCR and the principal target for endogenous opioid peptides and exogenous opioid analgesic agents. It is primarily involved in neuromodulation of pain perception, reward pathways, respiratory depression, and other physiological processes. Activation of MORs leads to analgesia but also underlies side effects such as euphoria or respiratory depression. The OPRM1 gene encodes multiple transcript variants, and a common single-nucleotide polymorphism has been associated with differences in addiction risk and pain sensitivity. MOR is targeted by most clinically important opioid analgesics for moderate-to-severe pain management.

Other names

μ-opioid receptorOPRM1

Activation of MORs couples to inhibitory G proteins (Gi), leading to inhibition of adenylate cyclase activity, reduced intracellular cAMP levels, and modulation of ion channel activity to decrease neuronal excitability.