Immunohistochemical study on the distribution of the voltage-gated calcium channel alpha(1B) subunit in the mature rat brain.

Many neuronal processes are regulated by calcium influx through voltage-gated calcium channels. Among these calcium channels, the N-type channel has been shown to play a significant role in the regulation of neurotransmitter release. This present report has demonstrated the distribution of the alpha(1B) subunit of the N-type calcium channel in the mature rat brain. The most striking findings were the highest immunoreactivity in the CA1 region of the hippocampus and the clear demarcation in the thalamus. Characteristic patterns of distribution were noted in the cerebral cortex, hippocampus, caudate-putamen, thalamus, and cerebellum. In the cerebral cortex, strong staining was seen in layers II-III and V. In the basal ganglia, the staining intensity was high in the caudate-putamen, whereas there was no immunoreactivity in the globus pallidus. Although the staining intensity was relatively low compared to that of the forebrain, moderate alpha(1B)-IR was found in the dorsal cochlear nucleus and mesencephalic trigeminal nucleus. The detailed features of this study will extend our current knowledge of alpha(1B) subunit distribution in terms of the number of neuroanatomical areas examined, by investigating alpha(1B) subunit protein expression, for the first time.