The Relative Importance of Nervous System and Hormones to the 2-Deoxy-D-Glucose-Induced Hyperglycemia in Fed Rats

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We examined the relative contributions of hormones and nervous system to the total 2-deoxy-D-glucose (2-DG)-induced central nervous system-mediated hyperglycemia. 2-DG was injected into the third cerebral ventricle in the following four groups of rats, and hepatic venous plasma glucose, immunoreactive glucagon, immunoreactive insulin, epinephrine, and norepinephrine were measured: 1) intact rats; 2) intact rats receiving somatostatin with insulin infusion through the femoral vein to inhibit glucagon secretion and maintain the basal insulin level; 3) bilateral adrenalectomized (ADX) rats to prevent epinephrine secretion; and 4) ADX rats receiving somatostatin with insulin infusion. Comparing areas under glucose curves among the intact rats, those receiving somatostatin with insulin infusion, ADX rats, and ADX rats receiving somatostatin with insulin infusion, the area under the glucose curve was intact rats greater than intact rats receiving somatostatin with insulin infusion greater than ADX rats receiving somatostatin with insulin infusion greater than ADX rats. These results suggest that there are three distinct sympathetic nervous system responses to 2-DG-induced central nervous system-mediated hyperglycemia. 2-DG-induced hyperglycemia is not dependent on only one of those three systems, it is dependent on all of them. The relative potency of the factors to 2-DG-induced hyperglycemia increases in the following order: direct neural innervation of liver (including suppressive epinephrine action on insulin secretion), glucagon, and direct epinephrine action on liver.