Effect of MK on hippocampal neuronal damage induced by KA injection. (A) Representative Nissl-stained sections from animals 24 hr after PBS (left panels), KA (0.2 μg/mouse, middle panels) or KA plus MK (0.4 μg/mouse, right panels) injection. Top panels shows at low magnification of the hippocampus. Scale bar: 400 μm. Middle and bottom panels show at high magnification of CA3 and dentate gyrus (DG) subregions of hippocampus. Scale bars: 200 μm. Note that the damaged areas induced by KA are indicated by absence of Nissl-positive neurons. (B) Quantification of undamaged Nissl-positive neurons for the hippocampal subregions CA1 and CA3, and hilus of dentate gyrus with different MK doses (0.1 -- 0.4 μg/mouse). Data are presented as mean ± SEM. * p < 0.05, as compared with PBS. # p < 0.05, as compared with KA. One-way ANOVA, Student-Newman-Keuls multiple comparison test.