ACTION OF INSULIN ON DEPOSITION OF GLYCOGEN AND STORAGE OF FAT IN ADIPOSE TISSUE

Abstract

After admn. of a large dose of either crystalline or protamine zinc insulin, the deposition. of glycogen in fat cells is significantly greater in diabetic than in normal rats. Moreover, a greater amt. of glycogen is deposited at the site of injn. than elsewhere. After daily injn. of large doses of protamine zinc insulin for 5-9 weeks into the fat of one groin of normal and diabetic rats, with control injns. of isotonic salt soln. into the other groin, hypertrophy of the insulin-injd. adipose tissue was demonstated. This was evidenced by an increase in wt. averaging 55% in the 27 diabetic animals and an increase in total lipids averaging 66% of the values obtained on the saline-injected, control side. Histological examination revealed an increase in the volume of the individual fat cells of the insulin-injected fat. It is concluded that insulin has a direct, local action on the adipose tissue at the site of injn. There is evidence to suggest that this may be due to a promoting action on the synthesis of fat from carbohydrate in the fat cell itself.