Effects of single ethanol administration on hepatic ornithine decarboxylase induction and polyamine metabolism.

The effects of a single ethanol administration on ornithine decarboxylase induction, polyamine metabolism and DNA synthesis in rat liver after partial hepatectomy were studied. Ethanol given 1 hr before partial hepatectomy at the dose of 2, 3 or 5 gm/kg body wt inhibited the increase in ornithine decarboxylase activity and that in the putrescine level in the liver 4 hr after partial hepatectomy. The hepatectomy increased the amount of ornithine decarboxylase messenger RNA expressed, and this amount was unaffected by ethanol administration. Further, ethanol did not accelerate the degradation of ornithine decarboxylase 4 hr after partial hepatectomy, indicating that the inhibition of ornithine decarboxylase activity caused by ethanol was not caused by a decrease in the ornithine decarboxylase messenger RNA level or by the acceleration of ODC degradation. The single dose of ethanol inhibited [3H]thymidine incorporation into the hepatic DNA 24 hr after partial hepatectomy. The suppression of [3H]thymidine incorporation was partially reversed by the administration of putrescine. These results suggested that ethanol inhibits the increase in ornithine decarboxylase activity after transcription, suppressing the accumulation of putrescine, which prevents DNA synthesis in response to hepatectomy.