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Related to endorphins: dopamine, serotonin


(ĕndôr`fĭnz), neurotransmittersneurotransmitter,
chemical that transmits information across the junction (synapse) that separates one nerve cell (neuron) from another nerve cell or a muscle. Neurotransmitters are stored in the nerve cell's bulbous end (axon).
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 found in the brain that have pain-relieving properties similar to morphine. There are three major types of endorphins: beta endorpins, found primarily in the pituitary gland; and enkephalins and dynorphin, both distributed throughout the nervous system. Endorphins interact with opiate receptor neurons to reduce the intensity of pain: among individuals afflicted with chronic pain disorders, endorphins are often found in high numbers. Many painkilling drugs, such as morphine and codeine, act like endorphins and actually activate opiate receptors. Besides behaving as a pain regulator, endorphins are also thought to be connected to physiological processes including euphoric feelings, appetite modulation, and the release of sex hormones. Prolonged, continuous exercise contributes to an increased production and release of endorphins, resulting in a sense of euphoria that has been popularly labeled "runner's high."


A family of endogenous morphinelike peptides present within the central nervous system. The term endorphin is generic, referring to all the opioid peptides, while specific peptides are given individual names, such as the enkephalins and β-endorphin. Their discovery has greatly enhanced the understanding of the mechanism of action of opiate drugs and how the perception of pain is modulated within the central nervous system. See Opiates, Pain

Morphine, codeine, and their many synthetic and semisynthetic analogs are effective pain killers that act through specific recognition sites, or receptors, localized on the surface of neurons within selected brain regions. These receptors have been extensively characterized, and a number of different subtypes have been identified which vary in their specificity for various opiates and opioid peptides and in the actions they mediate. The existence of these highly specific receptors implied that morphine was mimicking endogenous compounds within the brain with morphinelike actions, which have since been termed endorphins. See Morphine alkaloids

The first endorphins to be isolated were the enkephalins, two pentapeptides differing only in their fifth amino acid, which is either methionine or leucine. Since the initial description of the enkephalins, a number of opioid peptides have been reported that all share either the structure of methionine (Met) enkephalin or leucine (Leu) enkephalin as their first five amino acids. The major genes for these peptides have been identified. β-Endorphin is perhaps the most interesting peptide; it is cogenerated with important, nonopioid hormones.

The enkephalins are distributed unevenly throughout the brain, with very high levels in the basal ganglia, the thalamus, and the periaqueductal gray. In addition, there are high concentrations of enkephalins in the adrenal medulla, where they are co-released with norepinephrine in response to stress, among other stimuli. The dynorphins and α-endorphin are located within the central nervous system with a distribution similar to that of the enkephalins. See Stress (psychology)

β-Endorphin has been identified in only a single group of cells within the hypothalamus. Its highest levels are in the pituitary gland. Within the pituitary, both ACTH and β-endorphin are derived from the same precursor protein and are located within the same cells. Stimuli that release ACTH, a stress hormone which in turn induces the adrenal gland to release steroids, also co-release β-endorphin at the same time. Thus, stressful stimuli that release ACTH and norepinephrine also release both β-endorphin from the pituitary and enkephalins from the adrenal into the blood. This is particularly intriguing in view of the decreased perception of pain reported under periods of stress, such as combat. See Endocrine system (vertebrate)

All the endorphins can modulate the intensity of pain despite the fact that they act through different classes of opiate receptors. However, the presence of high concentrations of endorphins in brain regions unrelated to pain perception clearly demonstrates that the full range of actions of these compounds within the brain is not yet fully understood. Furthermore, their systemic hormonal role remains uncertain. See Nervous system (vertebrate)

References in periodicals archive ?
After getting regular doses of UV light, mice showed signs of withdrawal when their endorphins were silenced with naloxone: The animals' paws trembled, their teeth chattered and they shook like wet dogs.
When you only have to squeeze your thumb and finger and recall the memory for the feeling to flood back, you have created an endorphin switch.
Endorphin release may allow you to exercise more, too.
The endorphins that are released during an orgasm closely resemble morphine, and they effectively relieve pain," said Meston.
The discovery of the precise locations in the brain where endorphins are released provides a possible target for the development of more effective drugs for the treatment of alcohol abuse, said senior author Howard L.
Steven Keteyian, program director of preventive cardiology at the Henry Ford Heart & Vascular Institute in Detroit states that after only 15 minutes of intense exercise, increased endorphin levels are found.
It might not just have been the effect of endorphins which made me feel so happy after my day of hard physical gardening.
It has long been suspected that cutaneous endorphins are produced during exposure to UV light.
The act of simply listening to music without any intention for healing, will release endorphins to reduce stress in the body, balance left and right hemispheres of the brain, and thus create a better flow of energy within the individual.
The build-up of endorphins in the system may explain why children with Asperger's syndrome who have physical accidents report feeling less pain when the accidents occur in the afternoon or evening.
Alcohol-dependent patients, for example, are thought to have mesolimbic system dysregulations of dopamine, serotonin, endorphins, GABA, glutamate, acetylcholine, or endocannabinoid function.
Sweet foods (think chocolate) can stimulate the release of pain-relieving endorphins in the brain.