EFFECTS OF GLYCOLYTIC METABOLITES ON PRESERVATION OF HIGH-ENERGY PHOSPHATE LEVEL AND SYNAPTIC TRANSMISSION IN THE GRANULE CELLS OF GUINEA-PIG HIPPOCAMPAL SLICES

The present study was undertaken to investigate whether neural activit y of hippocampal slices can be preserved after replacing D-glucose wit h glycolytic intermediate metabolites such as lactate, pyruvate and ci trate or with other sugars such as fructose, mannose, maltose, glucosa mine, sucrose and galactose. As an index of neural activity, populatio n spikes (PS) were recorded in the granule cell layers after electrica l stimulation to the perforant path of guinea pig hippocampal slices. In addition, we determined the levels of ATP and creatine phosphate (C rP) in each slice after the replacement of D-glucose with these substr ates, and correlated it with the neural activity. Substrates other tha n D-glucose could not maintain the PS for even 20 min although the sli ces perfused with medium containing lactate, pyruvate, galactose, fruc tose and maltose maintained similar levels of ATP and CrP as in slices incubated in the D-glucose-containing medium. These results indicate that D-glucose is essential for the preservation of synaptic activity in addition to its main role as the substrate for energy production to maintain the levels of high energy phosphates.