Intracerebroventricular [ICV] administration of insulin lowers plasma glucose level in the rat

ABSTRACT

The effect of the central administration of insulin on plasma glucose and immunoreactive insulin [IRI] in normal and diabetic rats has been determined. Insulin [400 muU/kg/5 mul] was injected into the third cerebral ventricle stereotaxically. Blood samples were taken after 10, 30, and 60 minutes from insulin injections by heart puncture. In normal rats, the central administration of insulin significantly lowered plasma glucose level. A significant increase in plasma IRI level was also evident. Intracerebroventricular insulin-induced hypoglycemia was completely blocked by the prior administration of atropine [100 ug/kg i.p.]. In streptozocin [STZ] diabetic rats, intracerebroventricular injected insulin induced a significant fall in plasma glucose, but plasma IRI was not significantly altered. The role of this central action of insulin on plasma glucose regulation was discussed with special reference to other already known mechanisms