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

Histol Histopathol. 1998 Jan;13(1):29-36. doi: 10.14670/HH-13.29.


The inhibitory effects of topical indomethacin (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, pigmentation 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 erythematous reactions, while this agent showed no protective effects on epidermal pigmentation after UV-irradiation.

MeSH terms

  • Administration, Topical
  • Animals
  • Anti-Inflammatory Agents, Non-Steroidal / administration & dosage
  • Anti-Inflammatory Agents, Non-Steroidal / pharmacology*
  • Dinoprostone / blood
  • Dogs
  • Female
  • Indomethacin / administration & dosage
  • Indomethacin / pharmacology*
  • Male
  • Skin / drug effects*
  • Skin / pathology
  • Skin / radiation effects*
  • Skin Pigmentation / drug effects*
  • Skin Pigmentation / radiation effects*
  • Sunburn / pathology*
  • Sunburn / veterinary*
  • Ultraviolet Rays


  • Anti-Inflammatory Agents, Non-Steroidal
  • Dinoprostone
  • Indomethacin