Endorphins are naturally produced in response to pain. This phenomenon happens in both the Central Nervous System (CNS) and the Peripheral Nervous System (PNS). In the PNS, endorphins, primarily β-endorphin, are released from the pituitary gland and bind to μ-receptors. The binding of these two components inhibits the pain signal of the periphery nerves by blocking the neurotransmitter substance P. The mechanism in the CNS is similar but works by blocking a different neurotransmitter. When the endorphin binds to the μ-receptor, it inhibits the release of the neurotransmitter gamma-aminobutyric acid (GABA) which, in turn, increases the production and release of dopamine, the neurotransmitter associated with pleasure.
Their production can also be triggered by various human activities. Vigorous aerobic exercise can stimulate the release of β-endorphin which contributes to a phenomenon known as a “runners high.”
Laughter may also stimulate endorphin production; a 2011 study showed that attendees at a comedy club showed increased resistance to pain.Endorphins are also released during various activities including eating food, sex, orgasm, listening to music and eating chocolate. Research has also demonstrated meditation by trained individuals to trigger endorphin release.