Melanocortin receptor

Melanocortin receptors are members of the rhodopsin family of 7-transmembrane G protein-coupled receptors.
There are five known members of the melanocortin receptor system each with differing specificities for melanocortins:

. MC1R is associated with pigmentation genetics.
. MC2R is also known as the ACTH receptor or corticotropin receptor because it is specific for ACTH alone.
. MC3R is associated with childhood growth, accrual of lean mass and onset of puberty.
. Defects in MC4R are a cause of autosomal dominant obesity, accounting for 6% of all cases of early-onset obesity.
. MC5R

These receptors are inhibited by endogenous inverse agonists agouti signalling peptide and agouti-related peptide, and activated by synthetic and endogenous agonist melanocyte-stimulating hormones.

Selective ligands

Several selective ligands for the melanocortin receptors are known, and some synthetic compounds have been investigated as potential tanning, anti-obesity and aphrodisiac drugs, with tanning effects mainly from stimulation of MC₁, while anorectic and aphrodisiac effects appear to involve both MC₃ and MC₄. MC₁, MC₃ and MC₄ are widely expressed in the brain, and are also thought to be responsible for effects on mood and cognition.

Agonists

; Non-selective

; MC₁-selective

BMS-470,539

; MC₄-selective

; Unknown

Antagonists and inverse agonists

; Non-selective

;MC₂-selective

Atumelnant

; MC₄-selective

HS-014
HS-024
MCL-0042
MCL-0129
MPB-10
SHU-9119

Unknown

Semax