Influence of Cassia auriculata flowers on insulin receptors in streptozotocin induced diabetic rats: studies on insulin binding to erythrocytes

Abstract

In this paper, we investigated the insulin-receptor-binding effect of Cassia auriculata flower extract (CFEt) in
streptozotocin induced male wistar rats, using circulating erythrocytes as a model system. We measured the
levels of plasma glucose and plasma insulin and the binding of insulin to cell-membrane erythrocyte receptors
(ER) in CFEt and glibenclamide treated diabetic rats. The mean specific binding of insulin to ER was significantly
lower in diabetic control rats than in CFEt, glibenclamide treated diabetic rats, resulting in a significant decrease
in plasma insulin. Scatchard plot analysis demonstrated that the decrease in insulin binding was accounted for
by a lower number of insulin receptor sites per cell in diabetic control rats when compared with CFEt treated
rats. High-affinity (Kd1), low-affinity (Kd2), and kinetic analysis revealed an increase in the average receptor affinity
in ER from CFEt treated diabetic rats. The results suggest an acute alteration in the number of insulin receptors
on ER membranes in streptozotocin-induced diabetic control rats. Treatment with CFEt (2.40 ± 0.15) improved
specific insulin binding, with receptor number and affinity binding diabetic rats (0.95 ± 0.06). These biochemical
observations were supplemented by histopathological examination of pancreas section. The data presented here
showed that CFEt increase total ER membrane insulin binding sites with a concomitant (7.08 ± 0.51) increase in
plasma insulin.