NMDA receptor-mediated synaptic input to nitric oxide synthase-containing neurons of the guinea pig mesopontine tegmentum in vitro.

Intracellular recordings were obtained from laterodorsal tegmental (LDT) and pedunculopontine tegmental (PPT) neurons in a slice preparation to determine if excitatory synaptic input to the nitric oxide synthase (NOS)-containing cells was mediated by NMDA receptors. NOS cells were identified by intracellular injection of biocytin and NADPH-diaphorase histochemistry. Application of NMDA produced membrane depolarization, and EPSPs were reversibly reduced by an average of 46.3 +/- 16.6% with AP-5 (50 microM). These results indicate that post-synaptic NMDA receptors participate in synaptic transmission to NOS-containing neurons in LDT and PPT and are consistent with the hypothesis that synaptic NMDA receptors may control NO production in these cells.