Fig. 4.

Four isoforms of MBP (14, 17, 18.5, and 21.5 kDa) are regulated by phosphorylation during periods of increased activity of CA1 neurons. Each isoform was identified by comparison of Western blots with autoradiographs, with the exception of the 18.5 kDa isoform, which was identified by amino acid sequencing and phospho-peptide mapping (Atkins et al., 1997). Densitometric analysis of autoradiographs from hippocampal slices that received HFS of the alveus compared with control slices demonstrates increased phosphorylation of all four MBP isoforms (14 kDa, n = 6;p < 0.01; 17 kDa, n = 9;p < 0.001; 18.5 kDa, n = 14;p < 0.001; 21.5 kDa, n = 9;p < 0.001; ANOVA).