Effect of 1,25-dihydroxyvitamin D on S-adenosylmethionine decarboxylase in chick intestine.
The effect of 1,25-dihydroxyvitamin D on the activity of S-adenosylmethionine decarboxylase in the duodenal mucosa of vitamin D-deficient chicks was investigated. Enzyme activity increased dose-dependently in a biphasic manner with maximal responses at 1 and 6 h, due to an increase in Vmax in both cases. A second dose of 1,25-dihydroxyvitamin D, administered 6 h after the first, resulted in a significant increase in activity 1 h later, confirming the rapidity of the response. This early response was not seen with ornithine decarboxylase. The increase in S-adenosylmethionine decarboxylase activity particularly at 6 h may be due to a rise in cytosolic calcium, since hydrocortisone, an inhibitor of 1,25-dihydroxyvitamin D-stimulated calcium absorption, attenuates this enzyme's activity. Inhibitors of polyamine biosynthesis such as DL-alpha-difluoromethyl ornithine and methylglyoxal bis(guanylhydrazone) had no effect on calcium absorption, but the significance of this in evaluating the importance of 1,25-dihydroxyvitamin D stimulation of S-adenosylmethionine decarboxylase activity needs further investigation.
D012437:Adenosylmethionine Decarboxylase / Q000037:antagonists & inhibitors / Q000378:metabolism*; D000818:Animals; D002117:Calcitriol / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism; D002262:Carboxy-Lyases / Q000378:metabolism*; D002645:Chickens; D003609:Dactinomycin / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004386:Duodenum / Q000201:enzymology; D000518:Eflornithine; D004790:Enzyme Induction / Q000187:drug effects; D007408:Intestinal Absorption / Q000187:drug effects; D007413:Intestinal Mucosa / Q000201:enzymology*; D007700:Kinetics; D008935:Mitoguazone / Q000494:pharmacology; D009952:Ornithine / Q000031:analogs & derivatives / Q000494:pharmacology; D009955:Ornithine Decarboxylase / Q000378:metabolism; D065108:Ornithine Decarboxylase Inhibitors; D013096:Spermine / Q000096:biosynthesis; D013256:Steroids / Q000494:pharmacology
D065108:Ornithine Decarboxylase Inhibitors; D013256:Steroids; D003609:Dactinomycin; D013096:Spermine; D009952:Ornithine; D002262:Carboxy-Lyases; D009955:Ornithine Decarboxylase; D012437:Adenosylmethionine Decarboxylase; D002117:Calcitriol; D008935:Mitoguazone; D002118:Calcium; D000518:Eflornithine