The effects of chronic administration of T4, growth hormone and epidermal growth factor on hepatic lipogenic enzymes in hypophysectomised rats.

The effect of daily injections of T4, growth hormone and epidermal growth factor on the activities of the 3 hepatic enzymes malic enzyme (E.C.1.1.1.40), 6 phosphogluconate dehydrogenase (E.C.1.1.1.44) and glucose 6-phosphate dehydrogenase (E.C.1.1.1.49) in hypophysectomised rats was examined. T4 was shown to increase the activity of malic enzyme in a dose dependent manner from a basal level of 3.55 mumol/min/liver to 48.97 mumol/min/liver at a dose of 75 micrograms/Kg/day. A smaller increase in the activity of 6 phosphogluconate dehydrogenase was also observed over the same range of T4 dosage. Growth hormone in the current study increased the total liver enzyme activity of glucose 6-phosphate dehydrogenase by 84% when given with a replacement dose of 35 micrograms T4/kg/day and 6 phosphogluconate dehydrogenase activity by 19%.