How Are Endorphins Released?
The body’s workshop where many of these endorphins are made is the pituitary gland. Composed of three lobes, the pituitary gland is a pea-sized protrusion linked to the hypothalamus at the base of the brain. The hypothalamus handles many emotional and physical responses, including hunger and sexual bliss.
Endorphins though are often triggered in response to pain. Pain receptors send signals made of a neuropeptide called Substance P to the dorsal horn of the spinal cord, and from there onto the hypothalamus. These signals are the pain we experience after a trauma.
The hypothalamus next signals the pituitary gland by releasing corticotroponin-releasing hormone (CRH). This triggers the pituitary gland to start making a large protein known as proopiomelanocortin (POMC). It is from this manipulation of the POMC protein that endorphins are created.
Enzymes act on the POMC and cut it up into several kinds of peptide sub-units. Of these it is the beta-endorphins and (to a lesser extent) met-enkephalin which are the powerful analgesics. Another peptide which is created is alpha-melanocyte stimulating hormone. MSH regulates appetite and sexual behavior.
The brain has evolved to keep a certain level of endorphins topped up to ensure survival in the face of stress. This is for the purpose of maintaining our Fight-or-Flight reaction. But the brain also knows when to recognize overproduction. When endorphin levels get too high, feedback inhibition will occur, the hypothalamus shuting off CRH production.
How Do Endorphins Work?
Beta-endorphins work as analgesics by binding to opioid receptors in the brain and inhibiting Substance P production. This has the effect of reducing pain signals transmitted to the brain.