Melanotan I

Melanotan I (MT-I; [Nle4,D-Phe7]-α-MSH) is an α-MSH (HY-P0252) analog, synthetic melanotropic peptide, and melanocortin receptor (MCR) agonist. Melanotan I induces skin tanning by mimicking the action of α-MSH on the melanocortin 1 receptor (MC1R) in melanocytes. As an appetite suppressant, Melanotan I impairs the ability of insulin to inhibit endogenous glucose production, suppresses leptin secretion from adipose tissue, and thereby reduces voluntary feed intake in ewes. Melanotan I can be used in research related to UV-induced skin damage, polymorphic light eruption, ruminant feeding, and sexual dysfunction^[1][2][3]. In Vitro:Melanotan I (1.0 μM) does not enhance anchorage-independent clonogenic cell growth, a hallmark of malignancy, in freshly isolated human melanoma cell populations, with unaltered or slightly inhibited colony formation at 1.0 μM^[2].
Melanotan I inhibits proliferation of cultured human melanoma cell lines, demonstrating differentiating (melanogenic) activity^[2].
Melanotan I does not alter melanoma invasiveness in the human amniotic basement membrane model in vitro^[2].
Melanotan I stimulates cAMP production and subsequent eumelanin synthesis in cultured human melanocytes with some polymorphic MC1R variants^[2]. In Vivo:Melanotan I (0.03 nmol/h; intracerebroventricular administration; continuous infusion) reduces voluntary feed intake by 50% in adult Suffolk ewes, increases plasma thyroid hormone levels in a feed intake-independent manner, impairs the inhibitory effect of insulin on endogenous glucose production in undernourished ewes, and decreases plasma leptin levels in moderately undernourished ewes^[1].
Melanotan I (10 μM; topical administration) does not induce skin papillomas in vjun transgenic mice, but causes local skin pigmentation^[2].
Melanotan I (4 mg; subcutaneous injection; single sustained-release injection) increases the eumelanin content in guinea pig skin by 2.5-fold, induces persistent pigmentation lasting up to 10 months, and shows no toxicity^[2].