EVIDENCE THAT RECEPTORS CONTROLLING GROWTH-HORMONE AND HYPERGLYCEMIC RESPONSES TO GLUCOPRIVATION ARE LOCATED IN THE HINDBRAIN

Infusions of the glucose analogue 5-thioglucose (5TG) were performed either in the lateral or fourth ventricle in animals having a patent or blocked cerebral aqueduct in order to determine the location of glucoreceptor(s) responsible for the hyperglycemic and growth hormone (rGH) responses to glucoprivation. Infusion of 5TG in the fourth ventricle induced hyperglycemia and a decrease in rGH levels whether or not the aqueduct was patent. Infusion of 5TG in the lateral ventricle produced the hyperglycemic response without decreasing rGH in animals with the aqueduct patent whereas both responses were abolished in animals with the aqueduct blocked. These results indicate that glucoreceptors that mediate hyperglycemia and a decrease in rGH in response to cerebral glucoprivation are located in the hindbrain.