The expression of a NMDA receptor gene in guinea-pig myenteric plexus

Muscle tension studies of guinea-pig ileum longitudinal muscle-myenteric plexus preparations suggest that the N-methyl-D-aspartate (NMDA) receptor may be present in the enteric nervous system. Therefore, we investigated the expression of a gene for the NMDA receptor in guinea-pig taenia coli. The gene product was amplified using polymerase chain reaction (PCR) and its synthesis localized using in situ hybridization. A NMDA receptor PCR product from the myenteric plexus was demonstrated with nearly identical sequence characteristics to that in the brain. In situ hybridization studies identified myenteric neurons which express NMDA receptor messenger RNA. Demonstration of the genetic expression of the NMDA receptor supports a role for glutamate as a neurotransmitter in the enteric nervous system.