Expression of group I and II metabotropic glutamate receptors in trigeminal neurons during postnatal development

Trigeminal motoneurons (Mo5), mesencephalic trigeminal neurons (Me5), supratrigeminal neurons (Su5), and intertrigeminal neurons (I5) are important constituents of the neural circuitry responsible for jaw movements. Glutamate neurotransmission, mediated by ionotropic and metabotropic glutamate receptors (mGluRs), is critical for the production of jaw movements. To better understand the role of mGluR-mediated modulation of these neurons during early postnatal development, we conducted a series of experiments to illustrate the ontogeny of mGluRs 1, 5 (group I) and mGluRs 2, 3 (group II) in Mo5, Me5, Su5, and I5 neurons using receptor immunohistochemistry. Results demonstrate that the temporal expression of mGluRs is differentially regulated between, and within these trigeminal nuclei. The localization of group I and II mGluRs in these nuclei suggests a role for these receptors in mediating glutamatergic neurotransmission in brainstem circuits responsible for oral-motor behaviors.