EXPRESSION OF MESSENGER-RNA FOR THE N-METHYL-D-ASPARTATE (NMDAR1) RECEPTOR AND VASOACTIVE INTESTINAL POLYPEPTIDE (VIP) COEXIST IN ENTERIC NEURONS OF THE RAT

Anatomical, physiological and pharmacological evidence suggests that v asoactive intestinal polypeptide neurons are important mediators of th e descending inhibitory component of intestinal peristalsis. Pharmacol ogical data also indicate that glutamate may modulate intestinal motil ity. Recently, we demonstrated that mRNA coding for the glutamate N-me thyl-D-aspartate (NMDA) receptor is expressed by rat enteric neurons. In order to ascertain whether NMDA receptor message is expressed by va soactive intestinal polypeptide (VIP) neurons, we employed a double in situ hybridization technique. We hybridized tissue sections from the stomach, ileum and descending colon of adult rats with an NMDAR1 oligo probe and a VIP oligonucleotide. Enteric neurons expressing mRNA for b oth NMDA and VIP were found in the myenteric and submucosal ganglia at all of the sampling sites. These data suggest that the mechanism for glutamatergic excitation is present in VIP-containing enteric neurons.