title: The gender differences in the inhibitory action of UVB-induced melanocyte activation by the administration of tranexamic acid.
abstract: BACKGROUND
  Tranexamic acid has an inhibitory action on ultraviolet (UV) B-induced melanocyte activation. This study examined the sex differences in the inhibitory action of tranexamic acid on UVB-induced melanocyte activation.
  
  
  METHODS
  We irradiated the eye and ear of male and female mice with UVB at a dose of 1.0 kJ/m(2) using a 20SE sunlamp. We orally administered tranexamic acid (750 mg/kg/day) at 30 min before UVB exposure.
  
  
  RESULTS
  Tranexamic acid inhibited the UVB-induced epidermal melanocyte activation, and the effect was more remarkable under UVB eye irradiation than under UVB ear irradiation. Furthermore, the melanocyte activity suppression effect was stronger in female mice than in male mice. Following the administration of tranexamic acid, the female displayed increased blood levels of β-endorphin and μ-opioid receptor and estradiol receptor β expression in comparison with the male. Furthermore, the effect of melanocyte activity suppression in the female mice was decreased by the administration of tamoxifen (antagonist of estrogen receptor) or naltrexone (antagonist of μ-opioid receptor).
  
  
  CONCLUSIONS
  These results suggest that the suppression by tranexamic acid of the UVB-induced melanocyte activation (UVB sensitivity) is stronger in female mice than in male mice and that female hormones and β-endorphin play an important role in this sex difference.
authors.affiliation: Department of Pharmaceutical Sciences, Suzuka University of Medical Science, Mie, Japan.
authors.forename: Keiichi
authors.initials: K
authors.lastname: Hiramoto
authors.affiliation: Department of Pharmaceutical Sciences, Suzuka University of Medical Science, Mie, Japan.
authors.forename: Yurika
authors.initials: Y
authors.lastname: Yamate
authors.affiliation: R&D Department, Daiichi Sankyo Healthcare Co., LTD, Tokyo, Japan.
authors.forename: Daijiro
authors.initials: D
authors.lastname: Sugiyama
authors.affiliation: R&D Department, Daiichi Sankyo Healthcare Co., LTD, Tokyo, Japan.
authors.forename: Yumi
authors.initials: Y
authors.lastname: Takahashi
authors.affiliation: R&D Department, Daiichi Sankyo Healthcare Co., LTD, Tokyo, Japan.
authors.forename: Eiichi
authors.initials: E
authors.lastname: Mafune
mesh_terms: D000324:Adrenocorticotropic Hormone / Q000097:blood; D000818:Animals; D000933:Antifibrinolytic Agents / Q000097:blood / Q000494:pharmacology*; D004295:Dihydroxyphenylalanine / Q000032:analysis; D004423:Ear / Q000528:radiation effects; D004958:Estradiol / Q000097:blood; D047629:Estrogen Receptor beta / Q000378:metabolism; D005123:Eye / Q000528:radiation effects; D005260:Female; D008297:Male; D008544:Melanocytes / Q000737:chemistry / Q000187:drug effects* / Q000528:radiation effects*; D051379:Mice; D008811:Mice, Inbred DBA; D051739:Microphthalmia-Associated Transcription Factor / Q000235:genetics / Q000378:metabolism; D014442:Monophenol Monooxygenase / Q000378:metabolism; D009271:Naltrexone / Q000494:pharmacology; D009292:Narcotic Antagonists / Q000494:pharmacology; D017450:Receptors, Opioid, mu / Q000378:metabolism; D020845:Selective Estrogen Receptor Modulators / Q000494:pharmacology; D012737:Sex Factors; D012867:Skin / Q000187:drug effects* / Q000378:metabolism / Q000528:radiation effects*; D013629:Tamoxifen / Q000494:pharmacology; D014148:Tranexamic Acid / Q000097:blood / Q000494:pharmacology*; D014466:Ultraviolet Rays; D000521:alpha-MSH / Q000097:blood; D001615:beta-Endorphin / Q000097:blood; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism
chemical_list: D000933:Antifibrinolytic Agents; D047629:Estrogen Receptor beta; D051739:Microphthalmia-Associated Transcription Factor; C497235:Mitf protein, mouse; D009292:Narcotic Antagonists; D017450:Receptors, Opioid, mu; D020845:Selective Estrogen Receptor Modulators; D013629:Tamoxifen; D004958:Estradiol; D000521:alpha-MSH; D009271:Naltrexone; D001615:beta-Endorphin; D004295:Dihydroxyphenylalanine; D014148:Tranexamic Acid; D000324:Adrenocorticotropic Hormone; D014442:Monophenol Monooxygenase; D048051:p38 Mitogen-Activated Protein Kinases
keywords: estrogen receptor β; sex difference; tranexamic acid; ultraviolet B; β-endorphin