Mu-type opioid receptor (OPRM1) (OPRM1)

The Mu-type opioid receptor (MOR), primarily encoded by the OPRM1 gene, is a class A G protein-coupled receptor (GPCR) that serves as the principal mediator of the analgesic and rewarding effects of both endogenous and exogenous opioids [5, 11]. It is widely expressed throughout the central nervous system, including the thalamus, periaqueductal gray, and spinal cord, where it regulates nociception, mood, and motivation [10, 11]. In clinical contexts, MOR is the primary target for treating severe pain, but its activation is also central to the pathophysiology of opioid addiction and substance use disorders [7, 10]. Drugs that interact with this receptor range from clinical analgesics like morphine and fentanyl to extremely potent synthetic analogues like carfentanil, which is approximately 10,000 times more potent than morphine and used primarily in veterinary medicine for large animals [1, 12]. The molecular mechanism of MOR involves the inhibition of adenylate cyclase, resulting in decreased intracellular cAMP levels and the subsequent modulation of calcium and potassium channels to reduce neuronal excitability [2, 5]. Safety concerns associated with MOR modulation include life-threatening respiratory depression, rapid development of tolerance, and a high potential for physical dependence and abuse [12, 13].

Other names

OPRM1Mu opioid receptorMOPMu opiate receptorM-OR-1LMOROpioid receptor mu 1