N-methyl-D-aspartate (NMDA) and non-NMDA excitatory amino acid (EAA) receptor subtypes are involved in the integration of visceral afferent inputs within the nucleus of the solitary tract (NTS). Microinjection studies indicate interactions between nitric oxide (NO) and EAA receptors within the NTS. To examine these interactions at the single cell level, this study characterized the effects of the NO synthase inhibitor NG-nitro-L-arginine methyl ester (L-NAME) and the NO donor 3-[2-hydroxy-2-nitroso-1-propylhydrazino]-1-propanamine (PAPA-NONOate) on the excitatory responses of vagus nerve (VN)-evoked NTS neurons to the activation of (RS)-α-amino-3-hydroxy-5- methyl-4-isoxazolepropionic acid (AMPA) and NMDA receptors in rats. Iontophoresis of L-NAME did not alter spontaneous or VN-evoked discharges, but significantly decreased the number of action potentials (APs) evoked by iontophoretic application of AMPA. The effects of L-NAME on NMDA-evoked discharge were variable; for the population, L-NAME did not change the number of APs evoked by NMDA. PAPA-NONOate enhanced the spontaneous discharge and the number of APs elicited by AMPA but not NMDA. Iontophoresis of the inactive enantiomers NG-nitro-D-arginine methyl ester and hydroxydiazenesulfonic acid 1-oxide disodium salt had no effect on AMPA-evoked discharge. Our data suggest that NO facilitates AMPA-mediated neuronal transmission within the NTS.
|Journal||American Journal of Physiology - Heart and Circulatory Physiology|
|Issue number||1 53-1|
|State||Published - 1 Jan 2003|
- (RS)-α- amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid
- Nucleus of the solitary tract
- Vagus nerve stimulation