title: Attenuation of ultraviolet A-induced alterations in NIH3T3 dermal fibroblasts by melatonin.
abstract: BACKGROUND
  Sun exposure is responsible for long-term clinical skin changes such as photoageing, photodamage and photocancers. Ultraviolet (UV)A wavelengths stimulate the production of reactive oxygen species (ROS) that may contribute to photoageing. To protect against oxidative stress, skin cells have developed several defence systems, including ROS and metal ion scavengers and a battery of detoxifying, haem-degrading and repair enzymes. Melatonin's antioxidant activity is the result of three different but complementary actions: (i) a direct action due to its ability to act as a free radical scavenger; (ii) an indirect action that is a consequence of melatonin's ability to reduce free radical generation (radical avoidance); and (iii) its ability to upregulate antioxidant enzymes.
  
  
  OBJECTIVE
  In this study, we focused our attention on the prevention of photodamage, choosing melatonin as an antioxidant agent.
  
  
  METHODS
  In the present study we analysed the effects of pretreatment of murine fibroblasts cells (NIH3T3) with melatonin (1 mmol L(-1) ) followed by UVA irradiation (15 J cm(-2) ). Thereafter, changes in components of the extracellular matrix and in some antioxidant enzymes (inducible and constitutive haem oxygenase) were evaluated.
  
  
  RESULTS
  We observed that UVA radiation caused altered expression of extracellular matrix proteins and induced the expression of inducible haem oxygenase. This increase was not sufficient to protect the cells from damage. Instead, melatonin pretreatment led to increased expression of haem-degrading enzymes and suppression of UVA-induced photodamage.
  
  
  CONCLUSIONS
  These results suggest that melatonin, as a modifier of the dermatoendocrine system, may have utility in reducing the effects of skin ageing.
authors.affiliation: Section of Anatomy and Physiopathology, Department of Clinical and Experimental Sciences, Viale Europa 11, 25123, Brescia, Italy.
authors.forename: R
authors.initials: R
authors.lastname: Rezzani
authors.forename: L F
authors.initials: LF
authors.lastname: Rodella
authors.forename: G
authors.initials: G
authors.lastname: Favero
authors.forename: G
authors.initials: G
authors.lastname: Damiani
authors.forename: C
authors.initials: C
authors.lastname: Paganelli
authors.forename: R J
authors.initials: RJ
authors.lastname: Reiter
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000494:pharmacology*; D053148:Caspase 3 / Q000378:metabolism; D024042:Collagen Type I / Q000378:metabolism; D024043:Collagen Type II / Q000378:metabolism; D045304:Cytochromes c / Q000378:metabolism; D005347:Fibroblasts / Q000378:metabolism / Q000528:radiation effects*; D005353:Fibronectins / Q000378:metabolism; D005455:Fluorescent Antibody Technique; D051547:Heme Oxygenase-1 / Q000378:metabolism; D008550:Melatonin / Q000494:pharmacology*; D051379:Mice; D041681:NIH 3T3 Cells; D012867:Skin / Q000166:cytology / Q000378:metabolism / Q000528:radiation effects; D053773:Transforming Growth Factor beta1 / Q000378:metabolism; D014466:Ultraviolet Rays / Q000009:adverse effects*
chemical_list: D000975:Antioxidants; D024042:Collagen Type I; D024043:Collagen Type II; D005353:Fibronectins; D053773:Transforming Growth Factor beta1; D045304:Cytochromes c; D051547:Heme Oxygenase-1; D053148:Caspase 3; D008550:Melatonin