Μ-opioid receptor

Μ-opioid receptor (MOR) is a type of opioid receptor with high affinity for enkephalins and beta-endorphin but low affinity for dynorphins. It is considered the principal receptor target of the opioid drug morphine.

Structure

The Μ-opioid receptor is a G protein-coupled receptor (GPCR) that responds to the endogenous opioid peptides endorphin, enkephalin, and dynorphin. It is encoded by the OPRM1 gene. The receptor is a 400-amino acid polypeptide, with a molecular weight of approximately 50,000 daltons.

Function

The Μ-opioid receptor is involved in a variety of physiological functions, including pain perception, mood regulation, immune response, and gastrointestinal motility. Activation of the receptor by an agonist leads to inhibition of adenylate cyclase, decreased production of cAMP, and reduced neuronal excitability.

Pharmacology

The Μ-opioid receptor is the primary target of most opioid drugs, including morphine, heroin, and fentanyl. These drugs mimic the action of endogenous opioids to produce analgesia and euphoria. However, chronic use of these drugs can lead to tolerance and dependence.

Clinical significance

Alterations in Μ-opioid receptor function have been implicated in a variety of disorders, including chronic pain, addiction, and mood disorders. In addition, genetic variations in the OPRM1 gene have been associated with differences in pain perception and response to opioid drugs.

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