Activation of protein kinase C down-regulates glial but not neuronal taurine uptake

Phorbol myristate acetate (PMA), a protein kinase C (PKC) activator significantly decreased in a time- and dose-dependent manner taurine uptake by rat astroglial but not neuronal cells. The PMA-induced inhibition of taurine uptake by rat astrocytes was prevented by chelerythrine, a potent and selective inhibitor of PKC. The differential effect of PMA on rat neuronal and astroglial taurine transport was also obtained with the protein phosphatase inhibitor okadaic acid. This was not only the feature of rat cells since the same differential effects were obtained with human glioma GL15 and human neuroblastoma IMR32 cell lines. The results suggest that the neuronal and astroglial taurine transporter may be structurally different.