CAS Name: Melanotropin
Additional Names: melanophore-affecting hormone; melanocyte-stimulating hormone; melanophore hormone; melanophore dilating hormone; melanophore expanding hormone; melanophore-stimulating hormone; melanotropic hormone; chromatophorotropic hormone; melanosome-dispersing hormone; pigmentation hormone
Literature References: First known as Intermedin(e) or B hormone, a pituitary factor causing color changes in fish and amphibia: B. Zondek, H. Kron, Klin. Wochenschr. 11, 849 (1932). Subsequently, the hormone was identified as two linear peptides designated as a- and b-MSH. g-MSH, a third peptide has also been identified but has no significant melanocyte stimulating activity. The peptides are secreted by the pars intermedia of the pituitary gland. The brain may be a secondary site of synthesis. a-MSH derives from ACTH and b-MSH from b-lipotrophic hormone, q.q.v. These MSH precursors derive from two sections of pro-opiomelanocortin, q.v. A third portion of pro-opiomelanocortin may serve as the precursor of g-MSH. Biosynthesis: B. G. Jenks et al., J. Endocrinol. 98, 19 (1983); G. J. M. Martens et al., Gen. Comp. Endocrinol. 49, 73 (1983). Distribution and biosynthesis in the brain: D. F. Swaab et al., "The Distribution of MSH and ACTH in the Rat and Human Brain and its Relation to Pituitary Stores," in Endogenous Peptides and Learning and Memory Processes, J. L. Martinez, Jr. et al., Eds. (Academic Press, New York, 1981) pp 7-36. The mechanism of control of MSH release from the pituitary is still being investigated. There is evidence for inhibitory control by the brain via dopaminergic neurons, inhibitory control by the peptide melanostatin (MIF-1), q.v. and stimulatory control by b-adrenergic agents and the peptide CRF, q.v.: G. Schmitt et al., Neuroendocrinology 33, 306 (1981); P. G. Smelik et al., "The Role of Catecholamines in the Control of the Secretion of Pro-Opiocortin-Derived Peptides from the Anterior and Intermediate Lobes and its Implications in the Response to Stress," in The Anterior Pituitary Gland, A. S. Bhatnagar, Ed. (Raven Press, New York, 1983) pp 113-125; L. Proulx-Ferland et al., J. Steroid Biochem. 19, 439 (1983). Although the role of MSH in adaptive color change in lower vertebrates in well known, its physiological significance in mammals appears to be extrapigmentary. Effects on reproduction: M. E. Celis, M. Volosin, Prog. Clin. Biol. Res. 87, 113 (1982). Reviews of behavioral and neurochemical effects: P. C. Datta, M. G. King, Neurosci. Biobehav. Rev. 6, 297-310 (1982); B. E. Beckwith, C. A. Sandman, Peptides 3, 411-420 (1982). General reviews: Li, Adv. Protein Chem. 12, 270-295 (1957); Novales, Neuroendocrinology 2, 241 (1967); R. Schwyzer, Proc. Roy. Soc. London [Biol.] 210, 5-20 (1980); F. L. Strand, C. M. Smith, Pharmacol. Ther. 11, 509-533 (1980). Book: A. J. Thody, The MSH Peptides (Academic Press, New York, 1980) 162 pp.
Derivative Type: a-Melanotropin
Literature References: Contains 13 amino acids. Mammalian a-MSH is the most potent melanocyte-stimulating peptide known. Mechanism of action: T. K. Sawyer et al., Am. Zool. 23, 1983. Isoln from hog pituitary gland: T. H. Lee, A. B. Lerner, J. Biol. Chem. 221, 943 (1956); from pig pituitary gland: Harris, Lerner, Nature 179, 1346 (1957); Harris, Biochem. J. 71, 451 (1959); from horse pituitary gland: Dixon, Li, J. Am. Chem. Soc. 82, 4568 (1960). Structure: Lee et al., J. Biol. Chem. 236, 1390 (1961). Synthesis: Schwyzer et al., Helv. Chim. Acta 46, 870 (1963). Synthesis and biological activity of dogfish a-MSH: A. Eberle et al., Helv. Chim. Acta 61, 2360 (1978). Activity as centrally administered antipyretic agent: M. T. Murphy et al., Science 221, 192 (1983). Cardiovascular effects: D. J. Diz, D. M. Jacobowitz, Brain Res. 270, 265 (1983). Review of the a-melanotropinergic system and its role in the CNS: T. L. O'Donohue, D. M. Jacobowitz in Polypeptide Hormones, R. F. Beers, E. G. Bassett, Eds. (Raven Press, New York, 1980) pp 203-222.
Properties: [a]D25 -58.5 ± 2.5° (c = 0.38 in 10% acetic acid).
Optical Rotation: [a]D25 -58.5 ± 2.5° (c = 0.38 in 10% acetic acid)
Derivative Type: b-Melanotropin
Literature References: Contains 18-22 amino acids differing slightly from one species to another: Lee et al., J. Biol. Chem. 236, 1390 (1961). Isoln from hog pituitary gland: T. H. Lee, A. B. Lerner, loc. cit.; from pig pituitary gland: Geschwind et al., J. Am. Chem. Soc. 78, 4494 (1956); 79, 620 (1957); Harris, Roos, Biochem. J. 71, 434 (1959); from bovine pituitary gland: Geschwind et al., J. Am. Chem. Soc. 79, 6394 (1957); from human pituitary gland: Dixon, Biochim. Biophys. Acta 37, 38 (1960); Harris, Nature 184, 167 (1959). Synthesis of derivatives: Hofmann, Ann. N.Y. Acad. Sci. 88, art. 3, p 689 (1960). Synthesis of bovine b-melanotropin: Schwyzer et al., Helv. Chim. Acta 46, 1975 (1963); S. Lemaire et al., J. Med. Chem. 19, 373 (1976). Solid-phase synthesis of human and monkey b-melanotropins: Wang et al., Int. J. Pept. Protein Res. 5, 33 (1973); of camel bc1-MSH: Li et al., Biochemistry 14, 953 (1975); of camel bc2-MSH: S. Lemaire et al., loc. cit.; of dogfish b-MSH: H. Yajima et al., Chem. Pharm. Bull. 26, 571 (1978); of equine b-MSH: J. Izdebski et al., Int. J. Pept. Protein Res. 19, 327 (1982). It is probable that the human pituitary does not produce b-MSH. The substance reported as human b-MSH in early studies seems to have been an artifact formed by enzymatic degradation of b-LPH during the extraction procedure: K. Tanaka et al., J. Clin. Invest. 62, 94 (1978); A. J. Thody, loc. cit.
Derivative Type: g-Melanotropin
Literature References: Contains 12 amino acids. Discovered during nucleotide sequencing of cloned DNA for bovine pro-opiomelanocortin: S. Nakanishi et al., Nature 278, 423 (1979). May be an antagonist of b-endorphin or a partial agonist/antagonist of ACTH. Synthesis and biological activity: N. Ling et al., Life Sci. 25, 1773 (1979); K. Okamoto et al., Chem. Pharm. Bull. 28, 2839 (1980); W. A. Bijl et al., Rec. Trav. Chim. 100, 123 (1981). Radioimmunoassay: T. Shibasaki et al., Life Sci. 26, 1781 (1980). Behavioral profile in rats: J. M. Van Ree et al., ibid. 28, 2875 (1981). Comparison with a-MSH: T. L. O'Donohue et al., Peptides 2, 101 (1981). Review: J. M. Van Ree et al., Ciba Found. Symp. 81, 263-276 (1981).
Properties: [a]D20 -38.0° (c 0.5 in 10% acetic acid). [a]D23 -33.4° (c = 1.0 in 1% acetic acid).
Optical Rotation: [a]D20 -38.0° (c 0.5 in 10% acetic acid); [a]D23 -33.4° (c = 1.0 in 1% acetic acid)