GLUCOSE DEPRIVATION RESULTS IN A LACTATE PREVENTABLE INCREASE IN ADENOSINE AND DEPRESSION OF SYNAPTIC TRANSMISSION IN RAT HIPPOCAMPAL SLICES

The effect of glucose deprivation on adenosine levels and on synaptic transmission was investigated in rat hippocampal slices. Incubation of hippocampal slices either in glucose-free medium or in the presence of the glucose transport inhibitor cytochalasin B (50 muM) increased bath adenosine levels and depressed the extracellularly recorded synaptic potential or population spike. The addition of lactate (10 mM), a precursor for mitochondrial ATP generation, prevented the elevation in adenosine and the depression of the population spike. These results indicate that the neuroinhibitory modulator adenosine is elevated during glucose deprivation and contributes to the hypoglycemic depression of synaptic transmission. The increase in adenosine during glucose deprivation can be prevented by providing substrate for mitochondrial ATP generation. The present results indicate an interaction between lactate and adenosine such that an increase in lactate may contribute to a decline in adenosine production.