Reassessment of Central Neural Pathways Necessary for Adrenal Catecholamine Output in Response to Hypoglycemia

Abstract

SummaryInsulin-induced hypoglycemia produced a marked increase in adrenal catecholamine output in intact dogs as well as in dogs with midbrain transection at the level of the inferior colliculus. An increase in plasma FFA also occurred in these groups of animals with an increase in ACO. In 10 animals with cervical (C1) spinal cord transection in which the pH remained above 7.35 there was no increase in ACO or FFA following the production of severe hypoglycemia. In an animal with cervical spinal cord transection that developed an acidosis to pH 7.12, a rise in ACO occurred which returned to normal with correction of the acidosis. In a previous similar study pH was not followed and it seems likely that acidosis may have caused increased ACO in dogs with C1 transection. Our findings suggest that the locus at which hypoglycemia acts to initiate an increase in ACO and FFA is within the brainstem, below the level of the inferior colliculus.