In the present study, we showed that activation of metabotropic glutamate receptors in rat mesencephalic trigminal (Mes V) neurons (which are important in the genesis and control of oral-motor activities) can modulate hyperpolarization-activated inward current (Ih). Whole-cell recordings were obtained from rat Mes V neurons, and I_h was induced by a hyperpolarizing current or voltage pulses. Application of ACPD, which is a group I and II mGluRs agonist, suppressed the voltage-and time-dependent voltage sag under current-clamp recording, and suppressed the steady-state inward current under voltage-clamp recording, suggesting that it inhibited I_h. Further investigation revealed that group II mGluRs activation and the release of intracellular Ca^<2+> mediated ACPD-in-duced inhibition of I_h. Additionally, low-frequency (<10Hz) resonant properties exhibited at membrane potentials ranging from resting potential to hyperpolarization were substantially reduced by ACPD, indicating that modulation of I_h by mGluRs activation induces substantial changes in the frequency preference with which neurons respond to synaptic inputs.
Glutamatergic modulation of slow inward rectification in trigeminal primary sensory neurons
