| pro-opiomelanocortin | |||||||
|---|---|---|---|---|---|---|---|
| Identifiers | |||||||
| Symbol | POMC | ||||||
| NCBI gene | 5443 | ||||||
| HGNC | 9201 | ||||||
| OMIM | 176830 | ||||||
| RefSeq | NM_000939 | ||||||
| UniProt | P01189 | ||||||
| Other data | |||||||
| Locus | Chr. 2p23 | ||||||
| |||||||
Lipotropin is the name for twohormones produced by the cleavage ofpro-opiomelanocortin (POMC). Theanterior pituitary gland produces thepro-hormone POMC, which is then cleaved again to formadrenocorticotropin (ACTH) and β-lipotropin (β-LPH).
β-Lipotropin is a 90-amino acidpolypeptide that is thecarboxy-terminal fragment of POMC. It was initially reported to stimulatemelanocytes to producemelanin. It was also reported to perform lipid-mobilizing functions such aslipolysis[1] andsteroidogenesis. However, no subsequent studies have been published that support these early findings and no receptor has been identified for β-lipotropin.
β-Lipotropin can be cleaved into smaller peptides. In humans, γ-lipotropin,β-MSH, andβ-endorphin, are all possible fragments of β-lipotropin.[2] β-endorphin is the predominant opioid of the anterior human and rat pituitary gland. Birdsall and Hulme demonstrated that the C-fragment of lipotropin (β-endorphin) has a high affinity for opiate receptors in the brain, and the binding was reversed by naloxone, a classical antagonist of the opiates (Bradbury et al. 1976a). Alongside this, Feldberg found that β-endorphin administered in cat ventricles was 100 times more potent than morphine as an analgesic agent (Feldberg & Smyth 1976, 1977) and the analgesia persisted for several hours. Feldberg concluded that β-endorphin was the most potent analgesic agent known.β-Lipotropin is found in essentially equimolar concentrations to that ofcorticotropin. Evidence shows that β-Lipotropin is metabolized intoendorphins that can greatly affect mood and behavior and is thus regarded as aprohormone.[3]
γ-lipotropin is theamino-terminal peptide fragment of β-lipotropin. In humans, it has 56 amino acids. Gamma lipotropin is identical to the first 56 amino acid sequences of β-lipotropin. It can be cleaved toβ-melanocyte stimulating hormone.
In sheep, gamma-lipotropic hormone is a 58-amino-acid long pituitary polypeptide formed from the first 58 residues of beta-lipotropic hormone. Thecarboxyl-terminal of gamma-lipotropic hormone is identical to the structure of beta-melanophore-stimulating hormone.[4]
β-endorphin has been determined to have an analgesic effect. It produces effects similar to or characteristic of morphine.[5]
Lipotropin is on the Prohibited List of substances by the World Anti Doping Agency.[6] Lipotropin has also, under its alternate name AOD-9604 (Anti-Obesity Drug-9604),[7] been connected with controversies inAustralian Rules Football. Allegations have arisen around the use of the drug and its administration to players of theEssendon Football Club in theEssendon Football Club supplements saga, including weekly administration to players in the 2012 season.[8] The matters are currently under investigation due to the relationship between Lipotropin and growth hormones, as noted by club medical staff.[9]
In 2020 AOD-9604 underwent clinical trials into its use for the treatment of pain.[10]
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