title: Elevated insulin/glucagon ratios and decreased cyclic AMP levels accompany the glycogen and triglyceride storage syndrome in the hypothyroid chick.
abstract: The role of endogenous glucagon and insulin on the hepatic glycogen and triglyceride storage syndrome in propylthiouracil (PTU)-induced hypothyroidism was investigated in the chick. PTU feeding in the diet resulted in a progressive increase in liver glycogen concentration associated with a concomitant decrease in hepatic glucose-6-phosphatase (G-6-Pase) activity. Plasma glucagon level was significantly decreased and insulin significantly increased after two days of PTU administration. These enzyme and hormone changes were associated with a significant increase in hepatic glucose-6-phosphate (G-6-P) and a decrease in cyclic AMP levels. Although our results do not directly prove, the data does suggest that the hepatic glycogen storage syndrome observed in the PTU-induced hypothyroidism in the chick is mediated through changes in pancreatic glucagon and insulin secretion. The extent of glycogen accumulation was inversely related to G-6-Pase which is a rate limiting glycogenolytic enzyme. A significant increase in the plasma insulin/glucagon ratio, along with a significant decrease in the hepatic cyclic AMP concentration, could most likely also account for the excessive hepatic triglyceride accumulation in the PTU-treated chicks.
mesh_terms: D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D002645:Chickens / Q000378:metabolism*; D002784:Cholesterol / Q000378:metabolism; D000242:Cyclic AMP / Q000378:metabolism; D005934:Glucagon / Q000097:blood*; D005952:Glucose-6-Phosphatase / Q000378:metabolism; D006003:Glycogen / Q000378:metabolism*; D007037:Hypothyroidism / Q000139:chemically induced / Q000378:metabolism*; D007328:Insulin / Q000097:blood*; D008099:Liver / Q000378:metabolism*; D008297:Male; D010743:Phospholipids / Q000378:metabolism; D011441:Propylthiouracil; D014280:Triglycerides / Q000378:metabolism*
chemical_list: D001786:Blood Glucose; D007328:Insulin; D010743:Phospholipids; D014280:Triglycerides; D011441:Propylthiouracil; D006003:Glycogen; D005934:Glucagon; D002784:Cholesterol; D000242:Cyclic AMP; D005952:Glucose-6-Phosphatase