Expression of metabotropic glutamate receptors in nodose ganglia and the nucleus of the solitary tract

The purpose of this study was to identify the complement of metabotropic gl utamate receptors (mGluRs) expressed in nodose ganglia and the nucleus trac tus solitarius (NTS). mRNA from these tissues was isolated and amplified wi th standard RT-PCR with primers specific for each mGluR subtype. The result s of this analysis showed that the NTS expresses all eight mGluR subtypes, whereas nodose ganglia express only group III mGluRs: mGluR4, mGluR6, mGluR 7, and mGluR8. Application of the group III-specific mGluR agonist L-(1)-2- amino-4-phosphonobutyric acid (100 muM) reversibly inhibited voltage-gated calcium currents isolated from DiI-labeled aortic baroreceptor neurons and unlabeled nodose neurons. The results of this study suggest that group III mGluRs are the primary mGluR subtype expressed in visceral afferent neurons and that these receptors may be involved in afferent central transmission.