Involvement of nitric oxide in UVB-induced pigmentation in guinea pig skin.
Ultraviolet (UV) B irradiation evokes erythema and delayed pigmentation in skin, where a variety of toxic and modulating events are known to be involved. Nitric oxide (NO) is generated from L-arginine by NO synthases (NOS). Production of NO is enhanced in response to UVB-stimulation and has an important role in the development of erythema. NO has recently been demonstrated as a melanogen which stimulates melanocytes in vitro, however, no known in vivo data has been reported to support this finding. In this study, we investigated the contribution of NO with UV-induced pigmentation in an animal model using an NOS inhibitor. UVB-induced erythema in guinea pig skin was reduced when an NOS inhibitor, L-NAME (N-nitro-L-arginine methylester hydrochloride), was topically applied to the skin daily, beginning 3 days before UVB-irradiation. Delayed pigmentation and an increased number of DOPA-positive melanocytes in the skin were markedly suppressed by sequential daily treatment with L-NAME. Furthermore, melanin content 13 days after UVB-irradiation was significantly lower in skin treated with L-NAME than in the controls. In contrast, D-NAME (N-nitro-D-arginine methylester hydrochloride), an ineffective isomer of L-NAME, demonstrated no effect on these UV-induced skin responses. These results suggest that NO production may contribute to the regulation of UVB-induced pigmentation.
Horikoshi
T
T
Basic Research Laboratory, Kanebo Ltd, Odawara, Kanagawa, Japan. PXB12765@nifty.ne.jp
Nakahara
M
M
Kaminaga
H
H
Sasaki
M
M
Uchiwa
H
H
Miyachi
Y
Y
D000818:Animals; D004295:Dihydroxyphenylalanine / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004890:Erythema / Q000000981:diagnostic imaging; D006168:Guinea Pigs; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009569:Nitric Oxide / Q000378:metabolism*; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors; D011877:Radionuclide Imaging; D012867:Skin / Q000378:metabolism / Q000473:pathology; D012880:Skin Pigmentation / Q000528:radiation effects*; D014466:Ultraviolet Rays
D004791:Enzyme Inhibitors; D009569:Nitric Oxide; D004295:Dihydroxyphenylalanine; D019001:Nitric Oxide Synthase; D019331:NG-Nitroarginine Methyl Ester