Effect of Intracisternally Administered Insulin- 131 I in Normal and Vagotomized Dogs ∗

Abstract

Summary

Insulin, labeled with ¹³¹I, was injected intracisternally in normal and vagotomized dogs. In both types of experiments a significant fall in plasma glucose concentration was observed. The amount of insulin which passed into the blood from the cerebrospinal fluid, as determined by the amount of insulin-¹³¹I in the plasma, was more than sufficient to account for the observed hypoglycemia. These findings indicate that insulin enters the blood after intracisternal injection, and that the hypoglycemia observed after intracisternal insulin administration is most likely due to a peripheral rather than a central effect of insulin.