Immunohistochemical Study on the Distribution of the Voltage-gated Ion Channels in Gerbil Cerebellum

Chung, Yoon Hee; Kim, Kyung Hwan; Kim, Sung Su; Kim, Kyung Yong; Lee, Won Bok

Abstract

There is growing evidence that alterations in Ca2+ homeostasis may play a role in processes of brain aging and neurodegeneration. However, few have focused on voltage-gated Ca2+ channel (VGCC) subunits, much less on expression of other voltage-gated ion channels, i.e. voltage-gated K+ (Kv) and Na+ (Nav) channels. In the present study, we have investigated the spatial patterning of VGCCs, Kv1 and Nav channels by immunohistochemistry. This study have shown clearly that the VGCCs, Kv1 and Nav channels have differential distribution in the cerebellum of gerbil, which is used as an ischemia and epilepsy animal model. Immunoreactivities for Cav2.1, Cav1.2 and Cav1.3 were observed in the cell bodies and dendritic branches of Purkinje cells. In particular, Cav1.3 immunoreactivity was most prominent in the cell bodies and dendritic arborizations. A distinct band of punctate immunoreactivity for the Cav2.1, Cav2.2, Cav1.2 and Cav1.3 were observed in cerebellar nuclei. Strong immunoreactivities for Kv1.3, Kv1.4, Kv1.5 and Kv1.6 were observed in the Purkinje cell bodies, whereas Kv1.2 immunoreactivity was found in the basket cell axon plexus and terminal regions around the Purkinje cells. In the cerebellar nuclei, Kv1.2, Kv1.4 and Kv1.6 proteins were clearly detected in the soma of cerebellar output neurons. The most intense staining for Nav1.1 was observed in the granular layer, whereas strong immunoreactivity for Nav1.2 were seen in the Purkinje cell bodies, and extended into their dendrites. The overall results have demonstrated the expression patterns of VGCCs, Kv1 and Nav channels in gerbil cerebellum. Further studies are needed to define changes in other Ca2+ channel types to determine whether any channel changes represent selective loss of specific receptors or of cell loss, and to determine whether changes in Kv and Nav channels are linked to Ca2+ channel changes.