RESUMO
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.
Assuntos
Anti-Inflamatórios não Esteroides/farmacologia , Indometacina/farmacologia , Pigmentação da Pele/efeitos dos fármacos , Pigmentação da Pele/efeitos da radiação , Pele/efeitos dos fármacos , Pele/efeitos da radiação , Queimadura Solar/patologia , Queimadura Solar/veterinária , Administração Tópica , Animais , Anti-Inflamatórios não Esteroides/administração & dosagem , Dinoprostona/sangue , Cães , Feminino , Indometacina/administração & dosagem , Masculino , Pele/patologia , Raios UltravioletaRESUMO
The skin of adult hairless dogs is clinically nonpigmented, clinically lightly pigmented, or clinically hyperpigmented (spotty pigmented). The pigment noted clinically is attributable to melanin granules in the epidermis. Spotty pigmentation in the skin of adult hairless dogs was treated by administration of the depigmenting agent (3% hydroquinone, HQ) for 1 month. Depigmenting effects were examined by use of three methods: skin color, dihydroxyphenylalanine (DOPA)-positive melanocyte count, and histologic evaluation. The treated skin of hairless dogs began to become depigmented after application of HQ for 1 week. After 1 month of treatment with HQ, depigmentation spread over a quarter of the body. The number of DOPA-positive melanocytes in the HQ-treated sites decreased to less than approximately a fifth of that before treatment. In HQ-treated skin, histologic staining by use of Fontana-Masson's (FM) method revealed complete absence of melanin pigment. These results suggested that hairless dogs should be a useful animal model for investigating the effects and cutaneous toxicity of depigmenting agents.
Assuntos
Doenças do Cão/tratamento farmacológico , Hidroquinonas/uso terapêutico , Melanose/veterinária , Pele/efeitos dos fármacos , Animais , Animais Recém-Nascidos , Contagem de Células , Di-Hidroxifenilalanina/metabolismo , Doenças do Cão/metabolismo , Doenças do Cão/patologia , Cães , Feminino , Masculino , Melaninas/metabolismo , Melanócitos/metabolismo , Melanócitos/patologia , Melanose/tratamento farmacológico , Melanose/metabolismo , Melanose/patologia , Pele/metabolismo , Pele/patologia , Pigmentação da Pele/efeitos dos fármacosRESUMO
Histopathological changes in the dorsal skin of hairless descendants of Mexican hairless dogs (MHDs) exposed to artificial irradiation with high energy dose (180 kJ/m2) of ultraviolet (UV) rays (UVA + B) were investigated. Macroscopically, erythema and edema were observed in the irradiated skin at 1 day after irradiation (DAI), and blister formation occurred except one dog at 2 DAI. Erythema almost disappeared at 5 DAI, and at 6 DAI, the skin recovered to almost normal state. Light microscopically, sunburn cells were observed at 1 DAI. Then intercellular edema and blister formation in the epidermis and dermal edema were evident at 2 and 3 DAI. At 6 DAI, the skin showed almost normal features except for slight epidermal thickening, but melanin granules, which were distributed in almost the whole length of the epidermis before UV irradiation, were detected only in cells which seemed to be melanocytes except one dog. Dihydroxyphenylalanine (DOPA)-positive melanocytes almost disappeared at 1 and 2 DAI, and at 6 DAI, the number of DOPA-positive melanocytes increased over the level before UV irradiation. The ultrastructural features of melanocytes were characterized by vacuolated cytoplasm, decreased melanosomes, irregular-shaped nuclei and shortened dendrites at 1 DAI, and returned to normal at 6 DAI. These findings of melanocytes reflect the severity of the skin injury and support weak suntan reaction in this case. In conclusion, severe form of UV-induced skin injury seen in humans could be reproduced in hairless descendants of MHDs exposed to high energy dose of artificial UVA + B.
Assuntos
Lesões Experimentais por Radiação/patologia , Pele/patologia , Raios Ultravioleta/efeitos adversos , Animais , Vesícula/patologia , Di-Hidroxifenilalanina/metabolismo , Cães , Edema/patologia , Eritema/patologia , Histocitoquímica , Queratinócitos/efeitos da radiação , Queratinócitos/ultraestrutura , Masculino , Melanócitos/metabolismo , Melanócitos/efeitos da radiação , Melanócitos/ultraestrutura , Microscopia Eletrônica , Pele/ultraestrutura , Queimadura Solar/patologiaRESUMO
In the first experiment, the skin sebum and humidity, perspiration ability of sweat glands, and histology of spontaneous comedones were examined in hairless descendants of Mexican hairless dogs. The skin of females showed lower humidity than that of males. Some animals with a large number of comedones exhibited remarkably high skin sebum scores. The comedones were distributed throughout the dorsal skin, and a cluster of lesions was found mainly in the limbs and prepuces. The sweat glands showed no perspiration in the sudorific test. Histologically, both infant and adult animals had lesions of micro- and/or "blackhead" comedones. Plugged follicles containing abundant keratic substances associated well-developed sebaceous glands. Spontaneous comedones in the skin of hairless dogs were grossly and histologically similar to the acne vulgaris observed in human beings. The skin of some adult animals showed a large number of protrusive comedones which were solid cystic structures containing organized substances. In the second experiment, three kinds of antiacne agents (sulfur and camphor, sulfur and resorcinol, and ibuprofen piconol) were applied daily to the test sites for one month. These antiacne agents caused prominent extrusion of keratin plugs from follicular sites. The results suggest that the hairless dogs are a predictive model for evaluating the efficacy of antiacne agents proposed for acne treatment.
Assuntos
Acne Vulgar/patologia , Modelos Animais de Doenças , Doenças do Cão/patologia , Dermatopatias/patologia , Pele/fisiopatologia , Acne Vulgar/tratamento farmacológico , Acne Vulgar/fisiopatologia , Animais , Água Corporal/fisiologia , Cânfora/administração & dosagem , Doenças do Cão/tratamento farmacológico , Doenças do Cão/fisiopatologia , Cães , Quimioterapia Combinada , Condutividade Elétrica , Feminino , Ibuprofeno/administração & dosagem , Ibuprofeno/análogos & derivados , Ceratose/tratamento farmacológico , Ceratose/patologia , Masculino , Resorcinóis/administração & dosagem , Sebo/fisiologia , Pele/patologia , Dermatopatias/tratamento farmacológico , Dermatopatias/fisiopatologia , Enxofre/administração & dosagem , Suor/fisiologiaRESUMO
Dorsal skin reactions to irradiation with two different types of ultraviolet (UV) light sources (sunlight and artificial UV light) were investigated in hairless descendants of Mexican hairless dogs. The total energy dose of solar UV exposure and artificial UV irradiation was 90 kJ/m2 and 40 kJ/m2, respectively. Histological examinations were done up to 7 days after UV irradiation (7 DAI). At 1 DAI, the solar UV-exposed skin did not show marked changes, while artificial UV irradiated skin exhibited a visible erythematous reaction and prominent histological alterations such as epidermal thickening, appearance of sunburn cells and deformation elastic fibers. At 4 DAI of solar UV-exposure, the skin color became moderately dark and noticeable pigmentation developed in the epidermis. In contrast, at 4 DAI of artificial UV irradiation, there still remained moderate degeneration in the epidermis and dermis, and delayed tanning was weak. At 7 DAI of solar exposure, delayed suntan reactions became more prominent. Histologically, there were heavy pigmentation of melanin granules mainly in the stratum basale. On the other hand, artificial UV irradiated skin showed less pigmentation. Thus, solar exposure provoked remarkable pigmentation while artificial UV irradiation brought about severe sunburn reactions in the dorsal skin of hairless dogs.
Assuntos
Hipotricose , Pele/efeitos da radiação , Luz Solar/efeitos adversos , Raios Ultravioleta/efeitos adversos , Animais , Cães , Tecido Elástico/patologia , Epiderme/patologia , Eritema/etiologia , Feminino , Masculino , Mastócitos/patologia , Pigmentação/efeitos da radiação , Pele/patologiaRESUMO
Ultrastructural characteristics of the dorsal skin of hairless descendants derived from Mexican hairless dogs (3-month-, 1-year- and 5-year-old) were investigated and compared with those of age-matched beagles. Except that beagles had no melanocytes in epidermis, there was no essential difference in ultrastructural characteristics of epidermis between hairless dogs and beagles. In the Stratum basale of epidermis of hairless dogs, a small number of melanocytes and a few Langerhans cell (LC)-like cells were observed among keratinocytes. Melanocytes contained many melanosomes and a few premelanosomes. LC-like cells were characterized by electron-lucent cytoplasm and lobulated nucleus and lacked melanin granules, tonofilaments and desmosomal attachments. Unlike LC in humans and rodents, these LC-like cells did not contain Birbeck granules. Although age-related ultrastructural changes of dorsal skin were generally not clear both in hairless dogs and in beagles, cells containing melanin granules were not infrequently observed among dermal collagen bundles in 5-year-old hairless dogs.
Assuntos
Hipotricose/patologia , Pele/ultraestrutura , Animais , Núcleo Celular/ultraestrutura , Citoplasma/ultraestrutura , Grânulos Citoplasmáticos/química , Grânulos Citoplasmáticos/ultraestrutura , Cães , Epiderme/ultraestrutura , Feminino , Queratinócitos/ultraestrutura , Masculino , Melaninas/análise , Melanócitos/ultraestrutura , Microscopia EletrônicaRESUMO
Age-related changes in skin color and histologic features of hairless descendants of Mexican Hairless dogs were investigated and compared with those of haired descendants of Mexican Hairless dogs and Beagles. According to age, dogs studied were allotted to 4 groups: 0 to 2 weeks, 4 to 5 months, 1 to 1.5 years, and 3 to 4 years old. Skin color, histologic features, and numbers of dihydroxyphenylalanine (DOPA)-positive melanocytes were examined. The luminance values measured, using a spectrophotometer, decreased with advancing age up to 1.5 years, but they increased again at 3 to 4 years in hairless dogs. The number of DOPA-positive melanocytes in hairless dogs decreased with advancing age, whereas there were no DOPA-positive melanocytes in haired dogs and Beagles. Histologically, the epidermis of newborn hairless pups was thick. The border between the epidermis and dermis was wavy, and epidermal ingrowths were found projecting into the dermis. As hairless dogs grew older, the epidermis became thinner and flatter. Although numbers of hair follicles and sebaceous and apocrine sweat glands were apparently fewer in hairless dogs than in haired dogs and Beagles, these structures were detected at least up to 4 years of age. On the other hand, haired dogs and Beagles had a thin epidermis at birth and aging had little effect on their epidermal structures. The dermis of hairless dogs contained fewer mast cells than did that of haired dogs and Beagles.
Assuntos
Envelhecimento/fisiologia , Cães/fisiologia , Pigmentação da Pele , Pele/anatomia & histologia , Animais , Cruzamento , Feminino , Masculino , FenótipoRESUMO
Responses of the skin over the dorsum to solar UV irradiation (2 hours/d for 6 consecutive days) were investigated in hairless descendants of Mexican hairless dogs. Assessment of skin color changes, using a spectrophotometer, indicated that luminance values began to decrease from the third day of UV irradiation, reached the minimal value at 3 weeks, and almost recovered 12 weeks after completion of UV irradiation. The number of the dihydroxyphenylalanine-positive melanocytes increased significantly (P < 0.01) from the third day of UV irradiation, reached its maximal value at 2 weeks, and recovered to normal at 12 weeks after completion of UV irradiation. On the second day of UV irradiation, the epidermis became focally thick, with disarrangement of component cells that had degenerative changes. In addition, a few so-called sunburn cells with pyknotic nuclei were seen in the epidermis. On the third day of UV irradiation, apparent suntan reaction developed, and a large number of epithelial cells in the epidermis were heavily pigmented with melanin granules. At 12 weeks after completion of UV irradiation, the epidermis appeared almost normal. On the other hand, significant changes were not detected in the dermis throughout the study.
Assuntos
Cães/fisiologia , Pigmentação da Pele/efeitos da radiação , Pele/efeitos da radiação , Luz Solar , Raios Ultravioleta , Animais , Cruzamentos Genéticos , Cães/genética , Feminino , Masculino , Pele/citologia , Pele/patologiaRESUMO
The inheritance and breeding results of hairless descendants of Mexican hairless dogs (MHDs) were investigated. When the male hairless dogs were bred to female beagles, the birth ratio of hairless and haired dogs was 1:1. Mating between MHDs gave both hairless and haired pups. The results indicated that an autosomal dominant monogenic gene was responsible for their hairless characteristics. We propose the symbol Hm for this gene (hairless, Mexican type). The survival rate of hairless pups was markedly lower than that of haired ones. It was elevated to 50-90% by warming their cages to a minimum of 25 degrees C.
Assuntos
Cruzamento , Cães/genética , Animais , Coeficiente de Natalidade , Cães/fisiologia , Feminino , Cabelo/crescimento & desenvolvimento , Masculino , Taxa de SobrevidaRESUMO
Haematological and serum biochemical measurements were carried out in 1-year-old hairless and haired hybrids derived from the Mexican hairless dog (MHD). These hybrids included F1 hybrids obtained from male MHD and female Beagles, and BCF1 hybrids obtained from male hairless F1 and female Beagles. There were no significant differences between F1 and BCF1 hybrids, nor between male and female hybrids. Except for red blood cell counts, haemoglobin concentrations and packed cell volumes which were slightly higher in MHD-descendants than in Beagles, there were no differences for haematological and serum biochemical findings between hairless and haired hybrids when compared to age-matched Beagles.