Editorial Type:
Pharmacology

Coat color darkening in a dog in response to a potent melanotropic peptide

Paula D. Johnson From the Departments of Pediatrics (Johnson), Medicine (Dawson, Levine), Pharmacology and Oncology (Don), Anatomy (Hadley), and Chemistry (Hruby), College of Medicine, University of Arizona, Tucson, AZ 85724.

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 DVM, MS
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Brenda V. Dawson From the Departments of Pediatrics (Johnson), Medicine (Dawson, Levine), Pharmacology and Oncology (Don), Anatomy (Hadley), and Chemistry (Hruby), College of Medicine, University of Arizona, Tucson, AZ 85724.

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 MD
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Robert T. Dorr From the Departments of Pediatrics (Johnson), Medicine (Dawson, Levine), Pharmacology and Oncology (Don), Anatomy (Hadley), and Chemistry (Hruby), College of Medicine, University of Arizona, Tucson, AZ 85724.

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Mac E. Hadley From the Departments of Pediatrics (Johnson), Medicine (Dawson, Levine), Pharmacology and Oncology (Don), Anatomy (Hadley), and Chemistry (Hruby), College of Medicine, University of Arizona, Tucson, AZ 85724.

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Norman Levine From the Departments of Pediatrics (Johnson), Medicine (Dawson, Levine), Pharmacology and Oncology (Don), Anatomy (Hadley), and Chemistry (Hruby), College of Medicine, University of Arizona, Tucson, AZ 85724.

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Victor J. Hruby From the Departments of Pediatrics (Johnson), Medicine (Dawson, Levine), Pharmacology and Oncology (Don), Anatomy (Hadley), and Chemistry (Hruby), College of Medicine, University of Arizona, Tucson, AZ 85724.

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 PhD
DOI:
https://doi.org/10.2460/ajvr.1994.55.11.1593
Volume/Issue:
Volume 55: Issue 11
Received:
28 Dec 1993
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Online Publication Date:
01 Nov 1994
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Summary

Analogues of a melanocyte-stimulating hormone (α-msh) have been documented to be effective in inducing integumental melanogenesis in several species. These melanotropin analogues are more potent than the natural hormone and have prolonged biological activity, without apparent teratogenic or other toxic effects, at least in rodents. In a pilot study, a cyclic α-msh analogue, Ac-[Nle4,Asp5, D_-Phe7,Lys10⎴] α-msh4-10-NH2, was administered sc to a dog at a dose of 1 mg of analogue in 1 ml of 0.9 % NaCl for 3 weeks, without noticeable adverse effects. There was gradual and extensive darkening of the coat, which originally was predominantly tan, with tips of black. Initially, the darkening involved face and extremities, then gradually expanded to include the trunk and tail hair. Visual pigmentation peaked approximately 2 months after injections were completed. As new hair growth continued subsequent to the injections, the original tan color appeared at the proximal end of the hair shaft, leaving a dark terminal band on all affected hairs. These observations clearly indicated that follicular melanogenesis can be induced in dogs by treatment with a melanotropic peptide.

Summary

Analogues of a melanocyte-stimulating hormone (α-msh) have been documented to be effective in inducing integumental melanogenesis in several species. These melanotropin analogues are more potent than the natural hormone and have prolonged biological activity, without apparent teratogenic or other toxic effects, at least in rodents. In a pilot study, a cyclic α-msh analogue, Ac-[Nle4,Asp5, D_-Phe7,Lys10⎴] α-msh4-10-NH2, was administered sc to a dog at a dose of 1 mg of analogue in 1 ml of 0.9 % NaCl for 3 weeks, without noticeable adverse effects. There was gradual and extensive darkening of the coat, which originally was predominantly tan, with tips of black. Initially, the darkening involved face and extremities, then gradually expanded to include the trunk and tail hair. Visual pigmentation peaked approximately 2 months after injections were completed. As new hair growth continued subsequent to the injections, the original tan color appeared at the proximal end of the hair shaft, leaving a dark terminal band on all affected hairs. These observations clearly indicated that follicular melanogenesis can be induced in dogs by treatment with a melanotropic peptide.

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Cover American Journal of Veterinary Research
American Journal of Veterinary Research
Publication Date:
01 Nov 1994
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