ro-25-6981 and 4-(2--pyridyldithio)benzyldiazoacetate

Topics: Animals; Diazonium Compounds; Female; Long-Term Synaptic Depression; Phenols; Piperidines; Pyridines; Rats; Receptors, N-Methyl-D-Aspartate; Receptors, Presynaptic; Sulfonamides; Vestibular Nuclei

We investigated the role of the central NMDA receptor NR2 subunits in the modulation of nociceptive behavior and p-p38 MAPK expression in a rat model with compression of the trigeminal nerve root. To address this possibility, changes in air-puff thresholds and pin-prick scores were determined following an intracisternal administration of NR2 subunit antagonists. We also examined effects of NR2 subunit antagonists on the p-p38 MAPK expression.. Experiments were carried out using male Sprague-Dawley rats weighing (200-230 g). Compression of the trigeminal nerve root was performed under pentobarbital sodium (40 mg/kg) anesthesia. Compression of the trigeminal nerve root produced distinct nociceptive behavior such as mechanical allodynia and hyperalgesia. Intracisternal administration of 10 or 20 μg of D-AP5 significantly increased the air-puff threshold and decreased the pin-prick scores in a dose-dependent manner. The intracisternal administration of PPPA (1, 10 μg), or PPDA (5, 10 μg) increased the air-puff threshold and decreased the pin-prick scores ipsilateral as well as contralateral to the compression of the trigeminal root. Compression of the trigeminal nerve root upregulated the expression of p-p38 MAPK in the ipsilateral medullary dorsal horn which was diminished by D-AP5, PPPA, PPDA, but not Ro25-6981.. Our findings suggest that central NMDA receptor NR2 subunits play an important role in the central processing of trigeminal neuralgia-like nociception in rats with compression of the trigeminal nerve root. Our data further indicate that the targeted blockade of NR2 subunits is a potentially important new treatments strategy for trigeminal neuralgia-like nociception.

Topics: Animals; Behavior, Animal; Diazonium Compounds; Drug Administration Routes; Male; Motor Activity; Nociceptors; p38 Mitogen-Activated Protein Kinases; Phenols; Phosphorylation; Piperidines; Pyridines; Radiculopathy; Rats; Rats, Sprague-Dawley; Receptors, N-Methyl-D-Aspartate; Spinal Nerve Roots; Trigeminal Nerve; Up-Regulation