Modulation of regenerative membrane properties by stimulation of metabotropic glutamate receptors in rat deep dorsal horn neurons.

1. Intracellular recordings were obtained from 111 dorsal horn neurons in lamina V, in an in vitro transverse spinal cord slice preparation of the cervical region from young rats. 2. Of these neurons, 28% showed voltage-dependent plateau potentials, mainly underlain by a tetrodotoxin-resistant dihydropyridine-sensitive Ca2+ current. When depolarized, neurons with plateau properties produced accelerating firing frequency, afterdischarge, and bistability. They also exhibited windup of action potentials when stimulated by repetitive intracellular injections of current. 3. Glutamate being the main excitatory transmitter released by primary afferents, we also considered the effects of specific agonists of metabotropic glutamate receptors and showed that they modulate positively (induce or enhance) plateau properties in the deep dorsal horn neurons.