title: Evaluation of sunscreens with various sun protection factors in a new transgenic mouse model of cutaneous photoaging that measures elastin promoter activation.
abstract: BACKGROUND
  Long-term sun exposure can cause major alterations in the papillary dermis, resulting in the deposition of massive amounts of abnormal elastic material, termed solar elastosis. Previous work has demonstrated that this type of photodamage is accompanied by an increase in elastin and fibrillin messenger RNAs and elastin promoter activity.
  
  
  OBJECTIVE
  Our purpose was to develop a rapid and sensitive in vivo method for evaluating compounds offering protection against cutaneous photodamage.
  
  
  METHODS
  Using a line of transgenic mice that expresses the human elastin promoter linked to a chloramphenicol acetyltransferase reporter gene, we applied sunscreens with various sun protection factors to 5-day-old mice followed by 30 minimal erythema doses of solar simulating radiation for three consecutive days.
  
  
  RESULTS
  Solar simulating radiation alone resulted in a fivefold increase in elastin promoter activity. Sun protection factors of 2, 4, 8, and 15 yielded a reduction in promoter activity by 2.8%, 42.5%, 58.1%, and 70.3%, respectively.
  
  
  CONCLUSIONS
  These results confirm the use of this system as a rapid and sensitive in vivo model for evaluating compounds that protect against photodamage.
authors.affiliation: Department of Dermatology, Jefferson Medical College, Philadelphia, PA, USA.
authors.forename: E F
authors.initials: EF
authors.lastname: Bernstein
authors.forename: D B
authors.initials: DB
authors.lastname: Brown
authors.forename: T
authors.initials: T
authors.lastname: Takeuchi
authors.forename: S K
authors.initials: SK
authors.lastname: Kong
authors.forename: J
authors.initials: J
authors.lastname: Uitto
mesh_terms: D000818:Animals; D015500:Chloramphenicol O-Acetyltransferase / Q000187:drug effects* / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004549:Elastin / Q000096:biosynthesis; D006801:Humans; D051379:Mice; D008822:Mice, Transgenic; D012867:Skin / Q000201:enzymology*; D015595:Skin Aging / Q000187:drug effects*; D013473:Sunscreening Agents / Q000494:pharmacology*
chemical_list: D013473:Sunscreening Agents; D004549:Elastin; D015500:Chloramphenicol O-Acetyltransferase