title: Effects of UV irradiation on the sebaceous gland and sebum secretion in hamsters.
abstract: BACKGROUND
  Although an understanding of the photobiology of the skin has been extensively advanced recently, the effect of ultraviolet (UV) radiation on sebaceous glands is not well known.
  
  
  OBJECTIVE
  In this study, we examined the direct effect of UV radiation on cultured sebocytes from hamsters in vitro experimental system. Moreover, we examined whether UV-induced peroxidation of skin surface lipids may affect barrier function of horney layer.
  
  
  METHODS
  We irradiated cultured sebocytes from hamsters, which have similar biological characteristics to the human sebocytes, with UV radiation. Moreover, transepidermal water loss (TEWL) was examined after topical application of cholesterol or triglyceride (TG) and UV exposures on the back of hamsters.
  
  
  RESULTS
  The number of sebocytes were increased significantly (120-140%) after 4 days as compared with the non-irradiated controls. Lipid production in sebocytes was also increased on day 7 in an irradiation-dependent manner up to 4.1 times of the pre-irradiated level. When UVB was irradiated to TG- or cholesterol-applied skin at the minimum ear-swelling dose, TEWL increased twice or more as compared with UVB irradiation to unapplied sites. When in vitro-irradiated TG, in vitro-irradiated cholesterol, TG-peroxide (TG-OOH), and cholesterol-peroxide (CHO-OOH) were applied to the skin, TEWL increased significantly.
  
  
  CONCLUSIONS
  These results suggest that UVB may directly activate the functions of the sebaceous gland in vivo to produce increased amounts of sebum, which may undergo peroxidation by UV light and damage the barrier functions of the skin.
authors.affiliation: Department of Dermatology, Kansai Medical University, 10-15, Humizono-cho, Moriguchi, 570-8506, Osaka, Japan. akitomo@takii.kmu.ac.jp
authors.forename: Yasuchiyo
authors.initials: Y
authors.lastname: Akitomo
authors.forename: Hirohiko
authors.initials: H
authors.lastname: Akamatsu
authors.forename: Yuri
authors.initials: Y
authors.lastname: Okano
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Masaki
authors.forename: Takeshi
authors.initials: T
authors.lastname: Horio
mesh_terms: D000818:Animals; D002455:Cell Division / Q000528:radiation effects; D002478:Cells, Cultured; D002784:Cholesterol / Q000494:pharmacology; D006224:Cricetinae; D015603:Keratinocytes / Q000166:cytology; D015227:Lipid Peroxidation / Q000528:radiation effects; D008297:Male; D008647:Mesocricetus; D010545:Peroxides / Q000494:pharmacology; D012627:Sebaceous Glands / Q000166:cytology / Q000378:metabolism* / Q000528:radiation effects*; D012629:Sebum / Q000378:metabolism*; D012867:Skin / Q000378:metabolism / Q000528:radiation effects; D014280:Triglycerides / Q000494:pharmacology; D014466:Ultraviolet Rays / Q000009:adverse effects*; D014867:Water / Q000378:metabolism
chemical_list: D010545:Peroxides; D014280:Triglycerides; D014867:Water; D002784:Cholesterol