Enkephalins

Enkephalins are pentapeptides involved in regulating nociception in the body. The enkephalins are termed endogenous ligands, as they are internally derived and bind to the body's opioid receptors. Discovered in 1975, two forms of enkephalin were discovered, each derived from a different precursor: leu-enkephalin and met-enkephalin.

Structure and Function

Enkephalins are found in high concentrations in the brain and spinal cord, and are also present in the adrenal medulla, heart, kidneys, and other tissues. The sequences of enkephalins are:

• Met-enkephalin: Tyr-Gly-Gly-Phe-Met
• Leu-enkephalin: Tyr-Gly-Gly-Phe-Leu

Enkephalins function as "natural pain killers" by binding to opioid receptors and preventing the release of substance P, a neuropeptide that transmits pain.

Role in Disease

Alterations in enkephalin levels have been noted in a number of pathological conditions, including Alzheimer's disease, Parkinson's disease, and schizophrenia. In addition, enkephalins are thought to play a role in the development of addiction, as they are involved in the reward pathway of the brain.

Research and Therapeutic Potential

Research into the therapeutic potential of enkephalins is ongoing. Because of their role in pain modulation, enkephalins have been considered as potential therapeutic agents in the treatment of chronic pain conditions. However, their rapid degradation in the body has limited their clinical use.

See Also

• Opioid peptide
• Endorphins
• Dynorphins

References

Enkephalins Resources
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