X-Message-Number: 24796 Date: Mon, 11 Oct 2004 17:55:51 -0700 (PDT) From: Doug Skrecky <> Subject: goodbye grey hair? Photochem Photobiol. 2004 Jun 1 [Epub ahead of print] PROTECTIVE EFFECT OF SUPEROXIDE DISMUTASE AGAINST HAIR GREYING IN A MOUSE MODEL. Oxygen free radicals play a role in the aging process, and the protective effect of various antioxidants has been intensively studied, in particular for cutaneous aging. Besides hereditary factors, free radical mediated damage to melanocytes of the hair follicle has been considered as a mechanism for aging of the hair. It was the aim of this study to evaluate the role of photosensitization reactions for hair greying and to demonstrate potential protective effects of superoxide dismutase (SOD). Mice with black hair were depilated with the finger tips on a surface of 6 x 2.5 cm on both sides of the dorsum. The right side received five applications of a SOD containing gel before exposure to psoralen (concentration 0.5 mg/ml) plus UVA (365 nm, 4 J/ cm(2)). The left side was pre-treated in the same way with a gel free of SOD. When the hair started growing again, the SOD-protected side was covered with black hair, while the hair on the vehicle-treated side was grey or white in 27 of the 30 animals studied. The 0.01% SOD concentration was as protective as the 0.1% concentration. Heat-inactivated SOD, applied in another 5 animals, was not protective. Using fluorescent labelling of the SOD with fluorescein isothiocyanate, epifluorescence microscopy and digital imaging processing, we show that SOD applied to the skin surface penetrates through the follicular appendages, as well as through the unbroken stratum corneum. Our findings suggest that superoxide radicals, generated by interaction of UVA light with the sensitizer, initiated the formation of secondary products with well-known DNA-damaging effects, such as lipid peroxidation products and tumor necrosis factor alpha. SOD prevented the damage to melanocyte DNA by dismutating superoxide. Photosensitization may be another mechanism for hair greying, which can be influenced by antioxidants. Given the large number of exogenous and endogenous sensitizers, this mechanism deserves further study for human hair greying. Am J Vet Res. 1994 Nov;55(11):1593-6. Coat color darkening in a dog in response to a potent melanotropic peptide. Analogues of a melanocyte-stimulating hormone (alpha-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 alpha-MSH analogue, Ac-[Nle4, Asp5, D-Phe7, Lys10] alpha-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. Rate This Message: http://www.cryonet.org/cgi-bin/rate.cgi?msg=24796