Regional differences in glial cell modulation of synaptic transmission

Metabolic integrity of glial cells in field CA1 of the guinea pig hippocampus is critical to maintenance of synaptic transmission (Keyser and Pellmar [1994] Glia 10:237-243). To determine if this tight glial-neuronal coupling is equally important in other brain regions, we compared the effect of fluoroacetate (FAC), a glial specific metabolic blocker, on synaptic transmission in field CA1 to synaptic transmission in area dentata (DG). FAC was significantly more effective in decreasing synaptic potentials in CA1 than in DG. A similar regional disparity in the FAC-induced decrease in ATP levels was evident. Isocitrate, a glial specific metabolic substrate, prevented the FAC-induced synaptic depression in both CA1 and DG. The results suggest that glia of CA1 and dentate respond differently to metabolic challenge. Modulation of this glial-neuronal coupling could provide a regionally specific mechanism for synaptic plasticity. Additionally, site-specific glial-neuronal interactions can impact on a variety of physiological and pathophysiological conditions.