REGULATION OF NMDA RECEPTORS IN CULTURED HIPPOCAMPAL-NEURONS BY PROTEIN PHOSPHATASE-1 AND PHOSPHATASE-2A

PHOSPHORYLATION Of glutamate receptors is probably an important mechan ism for modulating excitatory transmission(1-4). However, there is lit tle direct evidence to indicate which protein phosphatases can dephosp horylate glutamate(5) or other ligandgated channels(6), although it is known that protein phosphatases 1 and 2A play a major part in modulat ing voltage(7-10) and second-messenger-gated channels(11). Here we rep ort that in cultured hippocampal neurons, the N-methgl-D-aspartate (NM DA) receptor can be regulated by endogenous and exogenous serine/threo nine protein phosphatases. Phosphatase inhibitors enhanced NMDA curren ts recorded using the perforated patch technique(13) or in cell-attach ed patches, whereas protein phosphatases 1 or 2A decreased the open pr obability of these channels in inside-out patches.