Down-regulation of delayed rectifier K+ channels in the hippocampus of seizure sensitive gerbils

In order to confirm the species-specific distribution of voltage-gated K+ (Kv) channels and the definitive relationship between their immunoreactivities and seizure activity, we investigated Kv2.x, Kv3.x and Kv4.x channel immunoreactivities in the hippocampi of seizure-resistant (SR) and seizure-sensitive (SS) gerbils. There was no difference in Kv2.1, Kv3.4, Kv4.2 and Kv4.3 immunoreactivity in the hippocampus between SR and SS gerbils. In comparison to SR gerbils, Kv3.1b immunoreactivity in neurons was significantly lower in SS gerbils instead Kv3.1b-immunoreactive astrocytes were clearly observed in SS gerbils (p < 0.05). Kv3.2 immunoreactivity was also significantly lower in neurons of SS gerbils than in those of SR gerbils (p < 0.05). Considering the findings of our previous study, these findings suggest that delayed rectifier K+ channels (Kv1.1, Kv1.2, Kv1.5, Kv1.6, Kv2.1 and Kv3.1-2), not A-type K+ channels (Kv1.4, Kv3.4 and Kv4.x), may be down-regulated in the SS gerbil hippocampus, as compared to SR gerbils.