Time-dependent involvement of autonomic nervous system in hyperglycemia due to 2-deoxy-D-glucose.

To determine the mechanism of time-dependent hyperglycemia due to intracranial injection of 2-deoxy-D-glucose (2DG), we examined the effects of various blockers of the autonomic nervous system on the hyperglycemia and hyperglucagonemia induced by intracranial injection of 2DG in male Wistar rats in light and dark periods. Hexamethonium inhibited the hyperglycemia in both light and dark periods but did not block the hyperglucagonemia in either period. Intracranial injection of 2DG did not affect the plasma insulin concentration in saline-treated control rats, but hexamethonium caused an increase in the basal plasma insulin concentration and further increase in the plasma concentration after 2DG injection in the light period. Phenoxybenzamine, an alpha-adrenergic blocker, inhibited the hyperglycemia only in the light period and the hyperglucagonemia only in the dark period and slightly stimulated the basal concentrations of insulin and glucagon only in the light period. Propranolol, a beta-adrenergic blocker, blocked the hyperglycemia and hyperglucagonemia and also lowered the basal plasma glucagon concentration in both periods. Atropine sulfate and atropine methyl nitrate, muscarinic blockers, inhibited hyperglycemia only in the light and dark period, respectively. In contrast, both drugs blocked the hyperglucagonemia in both periods. These findings suggest that the autonomic nervous system is involved time dependently in the hyperglycemia and hyperglucagonemia due to intracranial 2DG injection.