Effects of PKA and PKC modulators on high affinity glutamate uptake in primary neuronal cell cultures from rat cerebral cortex

In this study, the effects of various agents known to alter protein phospho rylation, via protein kinase C or A, on high affinity glutamate uptake were investigated in primary neuronal cell cultures of rat cerebral cortex. Inc ubating the culture dishes with chelerythrine or H89 (N-[2-(p-bromocinnamyl amino)ethyl]-5-isoquinolinesulfonamide) which inhibit PKC and PKA, respecti vely, dramatically decreased the glutamate uptake in a dose-dependent manne r. Saturation kinetic analysis showed that chelerythrine and H89 decreased the V-max (chelerythrine: -61%, P < 0.06; H89: -59%, P < 0.05) without affe cting the K-m of the transport process as compared to the control values. T hese inhibitory effects were counteracted by the corresponding protein kina se activators, i.e. PMA (phorbol-12-myristate 13-acetate) in the case of PK C and forskolin in the case of PKA, although these protein kinase activator s alone did not significantly affect the glutamate uptake. These results pr ovide evidence that, in primary cultures of neuronal cells, the high affini ty glutamate uptake may be regulated by both PKA and PKC-mediated phosphory lation processes. (C) 1999 Published by Elsevier Science Ltd. All rights re served.