title: Effect of dietary methionine, arginine and ornithine on the metabolism and accumulation of polyamines, S-adenosylmethionine and macromolecules in rat liver and skeletal muscle.
abstract: The interrelationship and possible causality of polyamine synthesis and the transmethylation pathway in the growth-retarding effects of inadequate or excess dietary methionine was studied in young male rats. Feeding the rats for 2 weeks diets containing toxic concentrations of methionine had no effect on polyamine and S-adenosylmethionine metabolism in skeletal muscle, but resulted in markedly elevated concentrations of S-adenosylmethionine and S-adenosylhomocysteine and slightly decreased accumulation of spermine and RNA in the liver. These changes were accompanied by liver-specific stimulation of methionine adenosyltransferase and reduction of spermine synthase activities. Inadequate arginine feeding or supplementation of the diets with ornithine or excess arginine resulted in no apparent changes in tissue methionine or polyamine metabolism and did not alleviate the effects of varied dietary methionine supply. Inhibition of putrescine synthesis by supplementing the diets with 2-difluoromethylornithine did not modify the effects of toxic concentrations of dietary methionine. It is suggested that although hepatic spermine synthase is sensitive to excess methionine feeding, methionine toxicity is not mediated by defective polyamine metabolism.
mesh_terms: D000596:Amino Acids / Q000494:pharmacology*; D000818:Animals; D001120:Arginine / Q000494:pharmacology; D001835:Body Weight / Q000187:drug effects; D004032:Diet; D000518:Eflornithine / Q000494:pharmacology; D008099:Liver / Q000378:metabolism*; D046911:Macromolecular Substances; D008715:Methionine / Q000494:pharmacology; D009132:Muscles / Q000378:metabolism*; D009952:Ornithine / Q000494:pharmacology; D011073:Polyamines / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D012436:S-Adenosylmethionine / Q000378:metabolism
chemical_list: D000596:Amino Acids; D046911:Macromolecular Substances; D011073:Polyamines; D012436:S-Adenosylmethionine; D001120:Arginine; D008715:Methionine; D009952:Ornithine; D000518:Eflornithine