title: Inhibition by epidermal extracts of the 12-O-tetradecanoylphorbol-13-acetate induced peak of ornithine decarboxylase activity in the mouse epidermis.
abstract: The time course of induction of epidermal ornithine decarboxylase (E.C. 4.1.117) (ODC) activity following a single topical application of 17 nmoles of 12-O-tetradecanoylphorbol-13-acetate (TPA) on hairless mouse skin was established. Prior intraperitoneal (i.p.) administration of a crude epidermal extract prepared from hairless mouse epidermis led to a time-dependent, 50% inhibition of the peak level of TAP-induced ODC activity. Maximum inhibition was observed when the extract was injected 1.5 h before TPA treatment. The crude epidermal extract did not affect ODC activity in vitro. Following the administration of epidermal extracts, the inhibition of the TPA-induced ODC-response correlated positively with the presence of epidermal G2-chalone activity (determined by a stathmokinetic method) whereas myocardial, skeletal muscle, or heat-inactivated epidermal extracts with no epidermal G2-chalone activity, had no effect on TPA-induced ODC activity. These results indicate a possible relationship between ODC-activity and the control of mitotic rate by G2-chalone.
mesh_terms: D000818:Animals; D002262:Carboxy-Lyases / Q000378:metabolism*; D004790:Enzyme Induction; D004817:Epidermis / Q000201:enzymology*; D006131:Growth Inhibitors; D051379:Mice; D008812:Mice, Hairless; D009132:Muscles; D009206:Myocardium; D009955:Ornithine Decarboxylase / Q000378:metabolism*; D010704:Phorbols / Q000494:pharmacology*; D012867:Skin; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology*; D014020:Tissue Extracts
chemical_list: D006131:Growth Inhibitors; D010704:Phorbols; D014020:Tissue Extracts; D002262:Carboxy-Lyases; D009955:Ornithine Decarboxylase; D013755:Tetradecanoylphorbol Acetate