HISTOLOGY AND HISTOPATHOLOGY

Cellular and Molecular Biology



Effects of indomethacin on sunburn and suntan reactions in hairless descendants of Mexican hairless dogs

T. Kimura1 and K. Doi2

1Research Center, Nihon Nosan Kogyo Co., Ltd., Takura, Ibaraki, Japan and 2Department of Veterinary Pathology, Faculty of Agriculture, The University of Tokyo, Bunkyo, Tokyo, Japan

Offprint requests to: Dr. T. Kimura, Research Center, Nihon Nosan Kogyo Co., Ltd., Takura 5246, Ibaraki 300-26, Japan

 

Summary. The inhibitory effects of topical indo-methacin (IM)-treatment on sunburn and suntan reactions after ultraviolet (UV)-irradiation were investigated in the dorsal skin of hairless descendants of Mexican hairless dogs. Skin color, plasma prostaglandin E2 (PGE2) and histological features were examined. At 1 day after UV-irradiation, the IM-untreated sites showed prominent erythema, while the IM-treated sites exhibited few visible erythematous reactions. From 4 days after UV-irradiation, both the IM-treated and -untreated sites began to develop skin pigmentation. Assessment of skin color changes, using a colorimeter, reflected precisely the color changes in visual sunburn and suntan reactions. Plasma PGE2 concentration began to increase from 2 hours after UV-irradiation, reached the maximal values at 24 hours and recovered at 96 hours after UV-irradiation. Histologically, at 1 day after UV-irradiation, the IM-untreated sites showed remarkable epidermal degeneration (thickening and sunburn cells) and moderate alteration in the dermis. On the other hand, the IM-treated sites showed only minor histological changes. At 4 days after UV-irradiation, deposition of melanin granules was found in both the IM-treated and -untreated sites. At 7 days after UV-irradiation, pig-mentation became more prominent in the stratum basale. These results revealed that UV-induced erythematous reactions of hairless dogs were closely related to the action of PGE2. Visually and histologically, topical IM-treatment had apparent inhibitory effects on erythe-matous reactions, while this agent showed no protective effects on epidermal pigmentation after UV-irradiation. Histol Histopathol 13, 29-36 (1998)

 

Key words: Erythematous reactions, Hairless dogs, Indomethacin, Prostaglandins, Ultraviolet

DOI: 10.14670/HH-13.29