Nuclear localization of Ca(v)2.2 and its distribution in the mouse central nervous system, and changes in the hippocampus during and after pilocarpine-induced status epilepticus.

To investigate the subcellular localization of Ca(v)2.2 calcium channel in the mouse central nervous system (CNS), and changes of Ca(v)2.2 at acute and chronic stages during and after pilocarpine-induced status epilepticus (PISE), in order to find out the roles it may play in epileptogenesis. Combined immunocytochemistry at both light and electron microscopic levels with real-time reverse transcription polymerase chain reaction (RT-PCR), cell transfection approach were used in this study. N-type calcium channel Ca(v)2.2 subunit was distributed in different regions of the mouse CNS. It was mainly localized in the nuclei in different types of neurones and in astrocytes. At acute stages during and after PISE, Ca(v)2.2 expression decreased in the stratum pyramidale of CA3 area and in the stratum granulosum of the dentate gyrus, but increased in the stratum lucidum of CA3 area and in the hilus of the dentate gyrus. At chronic stage at 2 months after PISE, increased expression of Ca(v)2.2 in both the strata granulosum and molecular of the dentate gyrus was observed. Ca(v)2.2 is a nuclear protein in neurones and astrocytes in the mouse CNS. Its translocation occurs at acute stages during and after PISE. The increased expression of Ca(v)2.2 in both the strata granulosum and moleculare of the dentate gyrus at chronic stage at 2 months after PISE may be involved in the occurrence of spontaneously recurrent seizures.