NMDA receptor and nitric oxide synthase activation regulate polysialylatedneural cell adhesion molecule expression in adult brainstem synapses

Here we report that synapses in the adult dorsal vagal complex, a gateway f or many primary afferent fibers, express a high level of the polysialylated neural cell adhesion molecule (PSA-NCAM). We show that electrical stimulat ion of the vagal afferents causes a rapid decrease of PSA-NCAM expression b oth in vivo and in acute slices. Inhibition of NMDA receptor activity compl etely prevented the decrease. Blockade of calmodulin activation, neuronal n itric oxide (NO) synthase, or soluble guanylyl cyclase and chelation of ext racellular NO mimicked this inhibition. Our data provide a mechanistic fram ework for understanding how activity-linked stimulation of the NMDA-NO-cGMP pathway induces rapid changes in PSA-NCAM expression, which may be associa ted with long-term depression.