IN-VIVO EFFECTS OF (-)-NICOTINE ON ETHANOL-INDUCED INCREASE IN GLUCOSE-UTILIZATION IN THE MOUSE CEREBELLUM

The purpose of this study was to investigate the possible in vivo effects of (-)-nicotine, ethanol. and an adenosine agonist N-G-cyclohexyladenosine (CHA) when injected individually as well as in various combinations on glucose utilization in the fresh cerebellar slices of mice. Mice received ICV (-)-nicotine or CHA followed 5 min later by a test dose of ethanol (2 g/kg; IF). Animals were killed 20 min postethanol-treatment and fresh slices (300 mu m) of cerebellum were incubated in a glucose medium in Warburg flasks using C-14-glucose as a tracer. Trapped (CO2)-C-14 was counted to estimate glucose utilization. Ethanol treatment markedly accentuated glucose utilization, whereas the pretreatment with (-)-nicotine (125 and 250 ng, ICV) resulted in a significant attenuation in the ethanol-induced increase in glucose utilization. However, ICV (-)-nicotine (125 ng) alone did not produce any change in the cerebellar glucose utilization. The attenuation of ethanol-induced increase in glucose utilization by (-)-nicotine was nearly totally blocked by ICV hexamethonium, a purported nicotinic antagonist, suggesting participation of cholinergic-nicotinic receptors. The (-)-nicotine pretreatment also significantly attenuated both the ICV CHA (25 ng)-induced increase in glucose utilization and the accentuation of ethanol-induced increase in glucose utilization by CHA. The antagonistic effect of (-)-nicotine on CHA- and ethanol-induced increase in glucose utilization indicating an interaction between (-)-nicotine and ethanol and between (-)-nicotine and adenosine may suggest involvement of postreceptor (nicotinic and adenosine) mechanisms including ionic channels.