Fig. 3.

The increase in MBP phosphorylation requires action potentials in CA1 axons. A, When TTX (500 nm) was applied to hippocampal slices, the population spike in stratum pyramidale was completely abolished (TTX). A representative control response is shown for comparison (CTL). Calibration: 2 msec, 4 mV.B, Tetanization of the alveus in the presence of TTX abolished the increase in MBP phosphorylation as shown by the representative autoradiograph. C, This was confirmed by the corresponding densitometric analysis (HFS) (n = 7). We did not observe any changes in MBP amount with this protocol (91 ± 8% of control;n = 11). Thus, action potentials generated in CA1 axons are necessary for neuron–glia signaling.