Characterization of specific insulin binding sites in rat testis following induced diabetes and experimental...

The presence of insulin-saturable binding sites in the rat testis have been demonstrated. Employing radioreceptor assay (RRA), the characteristics of insulin binding in both liver and testis of the normal (control) rats have been studied. Crude receptor binding at 37 degrees C after 18-20 hrs of incubation in Tris-HCl buffer at pH-7.5. The binding of 125I-insulin to liver and testis of the experimental rats, rendered diabetic for two months with single parenteral streptozotocin (STZ) administration (65 mg/Kg, BW, ip) was also studied. In the diabetic rats, the insulin binding in liver as compared to the control increased by over 92% (P 0.001); the increase in the binding of 125I-insulin to the testis of the diabetic rats however was not statistically significant. Similarly, insulin binding to the testis did not vary much after 3 days of starvation as against 84% (P 0.001) increase in the insulin binding to the liver of the fasted rats. These results suggest that testicular insulin receptors are similar to those of liver but may have a different physiological control.