Phosphofructokinase, a glycolytic regulatory enzyme has a crucial role for maintenance of synaptic activity in guinea pig hippocampal slices

Abstract

To clarify the importance of glucose metabolism in maintaining neural activity, we investigated the effects of lowering the concentration of glucose in perfusion medium on synaptic activity (population spikes, PS) and on the level of high energy phosphates in the region of dentate gyrus (DG), CA3 and CA1 area of hippocampal slices of guinea pig. Further we determined the activity of phosphofructokinase (PFK) and hexokinase (HK) of these areas. Lowering the concentration of glucose from 10 to 5, 4, 3, 1 and 0 (mM) caused a reduction in the PS amplitude. The PS in CA3 and CA1 region decayed and extinguished much faster than that in DG area. The ATP and CrP levels in these three areas were well preserved even after lowering the concentration of glucose to 3 mM, and the patterns of reduction showed no difference in these three areas. On the other hand, there were significant differences in the activity of PFK in the DG, CA3 and CA1 areas, in contrast with HK which showed no significant differences. PFK activity was highest in the DG area and followed by CA3 and CA1 regions. The sensitivity in maintaining synaptic activity to lowered glucose concentrations showed good parallels with the activity of PFK in these regions, indicating that non-oxidative glycolytic metabolism regulated by PFK is crucial for the maintenance of synaptic activity