| Abstract: | Changes in the activities of ornithine decarboxylase (ODC) and aryl hydrocarbon hydroxylase (AHH) were investigated in rat epidermis after wounding the skin and application of 7,12-dimethylbenz(a)anthracene (DMBA), 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), and several enzyme inhibitors. Wounding of the skin by vigorous shaving led to a marked induction of ODC activity with a peak at 6 hr. Topical application of a single dose of tetradecanoylphorbol-13-acetate to wounded skin did not affect the activities of ODC and AHH. Application of single large dose (2.5 mg) of DMBA increased AHH activity 7-fold without affecting ODC activity. DL-alpha-difluoromethyl ornithine, a specific irreversible inhibitor of ODC, almost completely abolished ODC activity but did not inhibit DMBA- or TCDD-induced AHH activity. Several potential modifiers, including retinoic acid, indomethacin, 1,3-diamino-2-propranol, alpha-naphthoflavone, and SKF 525 A had unequal effects on ODC and AHH activities. These data indicate that ODC and AHH induction processes in the epidermis are independent biochemical events that are not causally related. |
