Beta-endorphin

Beta-endorphin

[bey-tuh-en-dawr-fin or, especially Brit., bee-]
Beta-endorphin is an endogenous opioid peptide neurotransmitter found in the neurons of both the central and peripheral nervous system.

Sequence: "Tyr Gly Gly Phe Met Thr Ser Glu Lys Ser Gln Thr Pro Leu Val Thr Leu Phe Lys Asn Ala Ile Ile Lys Asn Ala Tyr Lys Lys Gly Glu

Formation

β-endorphin is a peptide, 31 amino acids long, resulting from processing of the precursor proopiomelanocortin (POMC). (Note, POMC also gives rise to other peptide hormones, including ACTH (Adrenocorticotropic hormone ), as well α- and γ-MSH (Melanocyte-Stimulating Hormone ), resulting from intracellular processing by internal enzymes known as prohormone convertases.)

β-endorphin is found in neurons of the hypothalamus, as well as the pituitary gland.

Function

It is an agonist of the opioid receptors, with evidence suggesting it serves as the endogenous ligand of the μ-opioid receptor, the same receptor to which the chemicals extracted from opium, such as morphine and codeine, have their analgesic and addictive effects (indeed, the μ-opioid receptor was named based on its most renowned ligand, morphine).

History

β-endorphin was discovered from camel pituitary extracts by C.H. Li and David Chung (Choh Hao Li and David Chung. Isolation and Structure of an Untriakontapeptide with Opiate Activity from Camel Pituitary Glands. PNAS 1976 73: 1145-1148.). The discovery was amidst a flurry of discoveries made in the opioid field of "endogenous opiates", including Met-enkephalin, Leu-enkephalin, and dynorphin. Shortly thereafter, also in C.H. Li's laboratory, the opioid effects of this peptide were characterized (Horace H. Loh, L. F. Tseng, Eddie Wei, and Choh Hao Li. β-Endorphin is a Potent Analgesic Agent. PNAS 1976 73: 2895-2898.) Some notable early questions which were investigated included anatomical questions (where in the body? where in the brain? where in the neuron?), pharmacological questions (how similar to morphine? how does potency differ? what part of the molecule confers opioid activity?), biochemical questions (how is it biosynthesized? how is the activity regulated? how is it metabolized?), behavioral questions (what is the effect of endogenous β-endorphin on activity levels), clinical questions (do deficiencies in endogenous β-endorphin lead to psychological disorders?), and therapeutic questions (is β-endorphin a viable treatment for morphine and heroin addiction, as well as chronic pain disorders?).

Effects

It is used as an analgesic in the body to numb or dull pains. That is the reason why we start to feel better immediately after an acute physical trauma even though the symptoms are still present. The reason the pain dulls is because it breaks down bradykinins, which accumulate in response to injury.

β-endorphin is believed to have a number of other benefits, including:

  • Boosting the immune system
  • Slowing the growth of cancer cells
  • Promoting feeling of well-being
  • Increasing relaxation

References

External links

  • - beta-endorphin (1-9)
  • - beta-endorphin (2-9)

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