Betaendorphin

Beta-endorphin is an endogenous opioid peptide that acts as a neurotransmitter and neurohormone in humans and other mammals. It is one of several opioid peptides derived from the larger proopiomelanocortin (POMC) precursor and is produced through proteolytic processing of POMC in the anterior pituitary and in subsets of neurons in the hypothalamus and brainstem. The mature peptide comprises 31 amino acids and is released into the bloodstream or synaptic spaces, sometimes in tandem with other POMC-derived products such as ACTH and beta-lipotropin.

Functionally, beta-endorphin binds primarily to mu-opioid receptors, producing analgesia and, in some contexts, euphoria or sedation. Its role in pain modulation is central, contributing to the endogenous analgesia system that is activated by stress, exercise, and tissue injury. In the brain the peptide participates in the regulation of stress responses, mood, and possibly appetite, while peripheral actions may involve immune modulation.

Measurement and significance: Variation in beta-endorphin levels has been studied in relation to pain conditions, mood disorders, stress, and substance use, but interpreting plasma measurements is complicated by multiple precursor fragments, tissue sources, and assay cross-reactivity. Beta-endorphin is one component of the broader endogenous opioid system, which includes enkephalins and dynorphins.

See also: Proopiomelanocortin, mu-opioid receptor, endogenous opioids, ACTH, beta-lipotropin.