Pattern of Compensatory Expression of Voltage-Dependent Ca~(2+) Channel α_1 and β Subunits in Brain of N-type Ca~(2+) Channel α_(1B) Subunit Gene-Deficient Mice with a CBA/JN Genetic Background

摘要

The Ca~(2+) channel α_(1B) subunit is a pore-forming component capable of generating N-type Ca~(2+) channel activity. Although the N-type Ca~(2+) channel plays a role in a variety of neuronal functions, α_(1B)-deficient mice with a CBA/JN genetic background show no apparent behavioral or anatomical-histological abnormality, presumably owing to compensation by other Ca~(2+) channels. In this study, we examined the mRNA expression of the α_(1A), α_(1C), α_(1D), α_(1E), β_1, β_2, β_3 and 耞4 subunits in the olfactory bulb, cerebral cortex, hippocampus and cerebellum of α_(1B)-deficient mice. We found that the mRNA expression levels of the α_(1A), α_(1C), α_(1D), α_(1E), β_1, β_2, β_3 and β_4 subunits were the same in the olfactory bulbs of wild, heterozygous and homozygous α_(1B)-deficient mice. In the cerebral cortex, α_(1A) mRNA in homozygous α_(1B)-deficient mice was expressed at a higher level than in wild or heterozygous mice, but no difference in the expression levels of the α_(1C), α_(1D), α_(1E), β_1, β_2, β_3 and ft subunits was found among wild, heterozygous and homozygous mice. In hippocampus and cerebellum, β_4 mRNA in homozygous α_(1B)-deficient mice was expressed at a higher level than in wild or heterozygous mice, but no difference in the expression levels of the α_(1A), α_(1C), α_(1D), α_(1E), β_1, β_2 and β_3 subunits was found among wild, heterozygous and homozygous mice. These results suggest that the compensatory mechanisms differ in differentbrain regions of α_(1B)-deficient mice with a CBA/JN genetic background.