Endorphins MEDECIN ABONNE

Definition

An endorphin (from the abbreviation endogenous morphine) is a neuropeptide opioid endogenous, that is to say a [ tooltip title=”A peptide is a polymer of amino acids linked together by peptide bonds”]peptide[/tooltip] acting as a neurotransmitter, produced by the body, acting on opiate receptors, without however being chemically related to the compounds opium. Endorphins are secreted in vertebrates during intense physical activity, excitement, pain and orgasm. They are found, among other places, in the brain and spinal cord as well as in the digestive system. Like opiates, and in particular morphine (hence their name), they have an analgesic capacity and provide a feeling of well-being or even euphoria.

Endorphin family

(Non-exhaustive list)

  • Beta endorphin
    made up of 31 amino acids. Has analgesic, euphoric and sedative effects via μ-opioid receptors
  • Alpha endorphin
    made up of 16 amino acids. Has analgesic and tranquilizing effects via μ opioid receptors
  • Enkephalins (met-enkephalin and leu-enkephalin)
    First endorphins discovered in 1975, made up of 5 to 8 amino acids. Has analgesic effects via δ and μ opioid receptors
  • Dynorphins (Dynorphin A, Dynorphin B, Alpha neo endorphin, Beta neo endorphin)
    Made up of 5 to 8 amino acids. Act through κ receptors (also bind to δ and μ). Their effects vary depending on the area of reception of these neuropeptides.
  • Endomorphin 1 and 2
    Discovery at the end of the 1990s, composed of 4 amino acids binding to the μ receptor
  • Nociceptin
    Made up of 17 amino acids. Bind to “atypical” opioid receptors. Its effect is variable, sometimes analgesic but also sometimes pro nociceptive

Action of endorphins

  • Reduction of pain (analgesia)
  • Decreased respiratory rate
  • Response to stress (well-being)
  • Decreased appetite (μ receptors are found in portal vein)
  • Plays a role in thermoregulation
  • Stimulates the production of dopamine which is involved in the phenomenon of reward and in certain sensations of pleasure
  • Has an antidepressant effect
  • Plays a role in mood

Their action passes through opiate receptors, especially μ, in the brain, the spinal cord and the digestive system.
Their action is inhibited by Naloxone.
The production of endorphins helps eliminate the background noise of the nociceptive system but not “abnormal” pain.

Factor modifying endorphin production

Factor increasing their production

  • Pain
  • The stress
  • Sport (30 minutes/day multiplies their production by 5)
  • Make love (multiplies their production by 5)
  • Satisfaction
  • Massages
  • Acupuncture
  • psychotherapy

Factor decreasing their production

  • Immobilization
  • Undernutrition
  • Chronic pain caused by exhaustion (fibromyalgia)
  • The Depression

 

Post operative chronic pain