Intracerebroventricular infusions of insulin increase vasopressin release in rats

1. The role of cerebral insulin or insulin-like immunoreactive substance (ILI) on arginine-vasopressin (AVP) release using rats was investigated. Feeding rats with a high salt diet for 4 weeks significantly decreased the contents of ILI in both the hypothalamus and pituitary gland. Intracerebroventricular infusions of insulin (4 and 40 micrograms/min for 30 min) increased plasma AVP concentrations dose-dependently without hypoglycaemia, but decreased hypothalamic and pituitary contents of AVP. 2. These results indicate that ILI in the brain may play a role in the secretion of AVP, and that this mechanism could be operated to control a water-sodium balance.