γ1-Melanocyte-stimulating hormone (γ1-MSH) is a peptide hormone produced by post-translational processing of proopiomelanocortin (POMC) in the pituitary gland.1 It selectively binds to melanocortin receptor 1 (MC1R) and MC3R over MC4R and MC5R (Kis = 0.025, 0.063, >100, and >100 ?M, respectively, in insect cells expressing the human receptors) but also binds to opioid receptors in rat brain tissue homogenates (IC50 = 5.9 ?M).2,3 γ1-MSH (10 ?M) inhibits contractions induced by the neuropeptide FMRF-amide in isolated M. edulis catch muscle.4 Intracisternal administration of γ1-MSH (0.3 nmol/animal) increases the latency to tail flick in the tail-flick test and inhibits haloperidol-induced catalepsy in mice.5 γ1-MSH (0.01 nmol/animal) also inhibits LPS-induced nitric oxide (NO) release in mouse forebrain in vivo.2
References:
[1]. Rubakhin, S.S., Churchill, J.D., Greenough, W.T., et al.Profiling signaling peptides in single mammalian cells using mass spectrometryAnal. Chem.78(20)7267-7272(2006).
[2]. Muceniece, R., Zvejniece, L., Liepinsh, E., et al.The MC3 receptor binding affinity of melanocortins correlates with the nitric oxide production inhibition in mice brain inflammation modelPeptides27(6)1443-1450(2006).
[3]. Oki, S., Nakao, K., Nakai, Y., et al.'γ-MSH' fragments from ACTH-beta-LPH precursor have an affinity for opiate receptorsEur. J. Pharmacol.64(2-3)161-164(1980).
[4]. Muneoka, Y., and Saitoh, H.Pharmacology of FMRFamide in Mytilus catch muscleComp. Biochem. Physiol. C Comp. Pharmacol. Toxicol.85(1)207-214(1986).
[5]. Klusa, V., Germane, S., Svirskis, S., et al.The γ2-MSH peptide mediates a central analgesic effect via a GABA-ergic mechanism that is independent from activation of melanocortin receptorsNeuropeptides35(1)50-57(2001).