Calcitonin induces ornithine decarboxylase in various rat tissues

A single dose of synthetic salmon calcitonin administered to rats (20 MRC U/kg body weight) stimulated the activity of ornithine decarboxylase in the brain, liver, kidney, testis and ovaries by 3-, 15-, 5-, 2- and 2-fold respectively after 4 h of the treatment. The increase in the enzyme activity in the brain, testis and ovaries was accompanied by a comparable increase in the enzyme protein content. Hepatic and renal ornithine decarboxylase concentration increased only by 2-fold. These results suggest that calcitonin influences polyamine biosynthesis through a tissue-specific regulation of the activity and/or the number of ornithine decarboxylase molecules.