Met-enkephalin is a naturally occurring opioid peptide that has opioid effects of a relatively short duration. It is one of the two forms of enkephalin, the other being leu-enkephalin. The enkephalins are considered to be the primary endogenous ligands of the δ-opioid receptor, due to their high potency and selectivity for the site over the other endogenous opioids. Met-enkephalin is also a ligand for the μ-opioid receptor, but with lower affinity.
Met-enkephalin is produced in a variety of tissues throughout the body, including the brain, spinal cord, and peripheral nervous system. It is also produced in the gastrointestinal tract, where it plays a role in regulating gut motility.
Met-enkephalin is thought to play a role in a variety of physiological functions, including:
- Pain modulation
- Stress response
- Mood regulation
- Reward and motivation
- Learning and memory
- Gastrointestinal function
Met-enkephalin levels are increased in response to pain and stress. This may help to reduce the perception of pain and to promote coping with stress. Met-enkephalin levels are also increased during exercise and sexual activity. This may help to explain the euphoric and rewarding effects of these activities.
Met-enkephalin is also thought to play a role in learning and memory. Studies have shown that met-enkephalin levels are increased in the hippocampus, a brain region involved in memory formation, after learning new information.
Met-enkephalin is metabolized by enkephalinase, an enzyme that breaks it down into smaller peptides. These smaller peptides are then excreted in the urine.
Potential therapeutic uses of met-enkephalin
Met-enkephalin has a number of potential therapeutic uses, including:
- Pain relief
- Treatment of addiction
- Treatment of depression and other mood disorders
- Treatment of cognitive impairments
- Treatment of gastrointestinal disorders
Side effects of met-enkephalin
Met-enkephalin is generally well-tolerated, but it can cause some side effects, such as:
- Nausea
- Vomiting
- Constipation
- Headache
- Dizziness
- Drowsiness
Met-enkephalin can also cause tolerance and dependence, so it should be used with caution.
Met-enkephalin is a naturally occurring opioid peptide with a variety of potential therapeutic uses. However, it is important to note that met-enkephalin can cause side effects, and it should be used with caution.
