TY - JOUR T1 - Na/HCO<sub>3</sub> Cotransporters in Rat Brain: Expression in Glia, Neurons, and Choroid Plexus JF - The Journal of Neuroscience JO - J. Neurosci. SP - 6839 LP - 6848 DO - 10.1523/JNEUROSCI.20-18-06839.2000 VL - 20 IS - 18 AU - Bernhard M. Schmitt AU - Urs V. Berger AU - Robert M. Douglas AU - Mark O. Bevensee AU - Matthias A. Hediger AU - Gabriel G. Haddad AU - Walter F. Boron Y1 - 2000/09/15 UR - http://www.jneurosci.org/content/20/18/6839.abstract N2 - We studied the expression and distribution of Na/HCO3cotransporters in rat brain using polynucleotide probes and polyclonal antibodies derived from the electrogenic rat kidney Na/HCO3cotransporter (rkNBC). In whole brain, we observed a single mRNA (∼7.5 kb) by Northern hybridization and a major ∼130 kDa protein by immunoblotting with a polyclonal antiserum directed against the C terminus of rkNBC. NBC mRNA and protein were present in cortex, brainstem–diencephalon, and cerebellum. In situhybridization revealed NBC mRNA expression throughout the CNS, with particularly high levels in olfactory bulb, hippocampal dentate gyrus, and cerebellum. NBC mRNA was present in glial cells (e.g., Bergmann glia of cerebellum and hippocampal astrocytes) and neurons (e.g., granule cells of dentate gyrus and neurons of cortex or striatum). Double hybridization of mRNA encoding NBC and glutamate transporter 1 (glial marker) confirmed that both glia and neurons express NBC. Indirect immunofluorescence microscopy demonstrated NBC protein throughout the CNS, particularly in hippocampus and cerebellum. Although NBC mRNA was restricted to cell bodies, NBC protein was distributed diffusely, compatible with a localization in cell processes and perhaps cell bodies. Double labeling with glial fibrillary acidic protein (astrocytic marker), microtubule-associated protein 2 (neuronal marker), or 2′,3′-cyclic mononucleotide 3′-phosphodiesterase (oligodendrocytic marker) demonstrated expression of NBC protein in specific subpopulations of both glia and neurons. Moreover, NBC protein was present in both cultured hippocampal astrocytes and cortical neurons. NBC mRNA and protein were also present in epithelial cells of choroid plexus, ependyma, and meninges. Our results are thus consistent with multiple novel roles for Na/HCO3 cotransport in CNS physiology. ER -