Hormonal control of liver regeneration

Abstract

Two peaks in cyclic AMP production in rat livers 4 and 12 hr after partial hepatectomy were confirmed and a third peak established at 22 hr, which is the peak of DNA synthesis. The increases in cyclic AMP were prevented by β adrenergic blocking agents, propranolol and pindolol, without affecting ornithine decarboxylase induction or DNA synthesis. The α blocking agents, phenoxybenzamine and phentolamine, given at the time of partial hepatectomy, delayed the rise in ornithine decarboxylase normally found 4 hr after operation, but did not affect DNA synthesis. If the α blocking agents were given at 9-12 hr or 18 hr, the onset of DNA synthesis was delayed. Phenoxybenzamine did not affect the induction of ornithine decarboxylase in intact rat livers by glucagon or growth hormone, but did inhibit induction by dexamethasone. The induction of ornithine decarboxylase produced by dexamethasone was inhibited by 17α hydroxyprogesterone; this compound also blocked the induction of ornithine decarboxylase in livers of partially hepatectomized rats.