Endorphins

Endorphins are peptides produced within the body that bind opioid receptors. They help regulate pain, stress responses, and reward.

Proopiomelanocortin: A precursor protein cleaved into several hormones and peptides, including beta-endorphin. Beta-endorphin is produced when this precursor is processed in specific cells.
Exercise-induced hypoalgesia: A temporary reduction in pain sensitivity following physical exercise. Endorphin release has been proposed as one contributor, though other systems also matter.
Neuropeptide: A short amino-acid chain used by neurons to signal to other cells. Endorphins belong to this broad class of signaling molecules.
Endocannabinoid system: A signaling network of endogenous cannabinoids, their receptors, and metabolic enzymes. It can produce exercise-related effects once attributed mainly to endorphins.
Positron emission tomography: An imaging technique that maps biological activity using radioactive tracers. PET tracers can estimate changes in opioid-receptor availability during pain or exercise.
Beta-endorphin: An endogenous opioid peptide derived from proopiomelanocortin that activates opioid receptors. This potent endorphin is a key example of the peptide family’s opioid activity.
Stress-induced analgesia: Reduced pain sensitivity during or after exposure to acute stress. Endogenous opioid release can help suppress pain during intense stress.
Peptide hormone: A hormone made from amino acids and typically acting through cell-surface receptors. Some endorphins also function as hormones when released into the bloodstream.
Endocannabinoid: A lipid signaling molecule made by the body that activates cannabinoid receptors. Endocannabinoids are chemically distinct from endorphin peptides but also influence pain and reward.
Opioid receptor: A receptor protein that binds opioid ligands and initiates cellular responses. Receptor imaging detects opioid-system activity but usually cannot identify endorphins alone.

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