Reduced insulin binding to hepatic plasma membranes in D-galactosamine-treated rats

Six to 12 hr after IP injection of 400 mg/kg of D-galactosamine in rats a 5-fold increase in plasma insulin was observed. In addition, impaired glucose assimilation was present after an IV Load in spite of unchanged fasting glucose levels. In streptozotocin-diabetic rats (100 mg/kg IV) plasma insulin remained diminished 12 h after induction of D-galactosamine hepatitis. Under identical conditions of preparation and incubation, the liver plasma membranes of D-galactosamine-treated rats, in both normal and diabetic states, bound only 40--60% as much insulin per mg of membrane protein as those of the control rats. Scatchard analysis suggested that this was due to a decrease in the number of receptor sites in the membranes of the D-galactosamine-injected rats. No difference in the insulin degrading capacity and in insulin-receptor dissociation of the plasma membranes between control and D-galactosamine-treated groups was found. These data suggest that a reduction in the number of hepatic insulin receptors in galactosamine hepatitis can lead to insulin resistance and hyperinsulinaemia.