Effect of growth hormone on liver glycogen accumulation in suckling rats

The regulation of liver glycogen turnover in the neonatal period differs from that of the adult state. Little is also known about the regulation exerted by GH in the first period of life. To shed light on the regulation of glycogen production and in particular to study the role of GH on liver glycogen accumulation, we investigated the effect of GH administration in control or GH-deficient neonatal rats. A slow-release GH preparation was injected subcutaneously on days 9 and 12 of life, in normal and neonatally treated rats with thyroxine or cortisol. Seventy-two hours after the last GH administration, liver glycogen was increased without concomitant elevation of plasma insulin and corticosterone levels and in addition without sequential inactivation of glycogen synthase. These data strongly suggest that the current concepts on the regulation of the hepatic synthesis of glycogen should be revised.