title: Inhibition by 1 alpha, 25-dihydroxyvitamin D3 of induction of epidermal ornithine decarboxylase caused by 12-O-tetradecanoylphorbol-13-acetate and teleocidin B.
abstract: Topical application of 1 alpha, 25-dihydroxyvitamin D3 [1 alpha, 25-(OH)2D3], an active form of vitamin D3, markedly inhibited induction of ornithine decarboxylase caused by 12-O-tetradecanoylphorbol-13-acetate (TPA) and teleocidin B in mouse skin. The degree of inhibition was dependent on the dose and time of application of 1 alpha, 25(OH)2D3. Application of 1 micrograms 1 alpha, 25(OH)2D3 within 30 min before or after treatment with 10 micrograms TPA caused about 72% inhibition of ODC induction at 4 hr. Similar degrees of inhibition were obtained with dose ratios of 1 alpha, 25(OH)2D3 to TPA of 1:3, 1:10, and 1:30. The dose required for 50% inhibition was 0.063 micrograms, or 0.15 nmol, which is about one-half that of retinoic acid, a known inhibitor of induction of ODC activity by TPA. 1 alpha, 25(OH)2D3 had a specific inhibitory effect, in which 100 times higher doses or more of other derivatives of vitamin D3, such as 1 alpha-hydroxyvitamin D3, 25-hydroxyvitamin D3, 24R,25-dihydroxyvitamin D3, and vitamin D3, were required to inhibit ODC induction by TPA. 1 alpha, 25(OH)2D3 did not inhibit epidermal hyperplasia induced by TPA.
mesh_terms: D000470:Alkaloids / Q000494:pharmacology*; D000818:Animals; D002117:Calcitriol / Q000494:pharmacology*; D004336:Drug Antagonism; D004790:Enzyme Induction / Q000187:drug effects; D005260:Female; D007700:Kinetics; D008235:Lyngbya Toxins; D051379:Mice; D008815:Mice, Inbred Strains; D009955:Ornithine Decarboxylase / Q000096:biosynthesis*; D010704:Phorbols / Q000494:pharmacology*; D012867:Skin / Q000187:drug effects / Q000201:enzymology*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology*; D014212:Tretinoin / Q000494:pharmacology
chemical_list: D000470:Alkaloids; D008235:Lyngbya Toxins; D010704:Phorbols; C022176:teleocidins; D014212:Tretinoin; D009955:Ornithine Decarboxylase; D002117:Calcitriol; D013755:Tetradecanoylphorbol Acetate