Beta-Endorphin

Pain / Mood / Stress

Also known as: beta-Endorphin, Beta-EP, POMC Fragment 237-267

Endogenous Opioid PeptidesResearch phase: Endogenous hormone (well characterized)Regulatory: Endogenous peptide. Not used as a drug. Opioid drugs target the same receptors.

Mechanism

Beta-endorphin is the body's most powerful natural painkiller — approximately 18-33 times more potent than morphine on a molar basis. This 31-amino-acid peptide is released from the pituitary and hypothalamus during intense exercise ("runner's high"), stress, and pain. It activates mu-opioid receptors to produce analgesia, euphoria, and stress relief.

Technical detail

Beta-endorphin is a 31-amino-acid endogenous opioid peptide derived from POMC (residues 237-267) via PC2 processing in the arcuate nucleus and anterior pituitary. It is a high-affinity mu-opioid receptor (MOR) agonist with lower affinity for delta-opioid receptors. MOR activation couples through Gi/Go to inhibit adenylyl cyclase, open GIRK K+ channels (hyperpolarization), and close voltage-gated Ca2+ channels, reducing neurotransmitter release in pain pathways. Co-released with ACTH from corticotrophs during HPA axis activation. Also modulates immune function via opioid receptors on lymphocytes.

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