Stimulation of Thirst and ADH Release After Intracranial Injection of Insulin in the Dog

Abstract

Insulin injected subcutaneously has been established to elicit drinking in the rat [2,4]. Intravenous (i.v.) administration of this hormone has been also reported to cause an increase in plasma vasopressin (ADH) concentration in man [1]. Both, stimulation of thirst in the rat and release of ADH in man have been suggested to be mediated by hypoglycaemia. A recent finding that i.v. administration of insulin or glucose causes some elevation of this hormone concentration in the cerebrospinal fluid CSF [7] prompted us to investigate whether stimulation of thirst and release of ADH may be caused by direct action of inulin on the central nervous system. To this end small doses of insulin were injected to the third cerebral ventricle (3rdV) of the dog and its effect on plasma antidiuretic activity (ADA) and spontaneous water intake measured.