Growth hormone normalizes hepatic lipase in hypothyroid rat liver.

The effects of growth hormone (GH) administration on hepatic lipase (HL) activity and mRNA levels were studied in pair-fed hypothyroid rats. In the hypothyroid state, liver HL mRNA levels and liver and postheparin plasma HL activities were decreased. In hypothyroid rats, GH normalized HL mRNA levels and HL activity in postheparin plasma; GH also increased the activity of HL in the liver, which remained lower than that in controls. These data indicate that at least part of the decrease of HL activity during hypothyroidism is due to the concomitant GH deficiency, and that GH rather than thyroid hormone may regulate HL mRNA levels.