NMDA receptor mediates the response of trigeminovascular neurons of rats

The present study was performed to evaluate the characteristics of excitatory amino acid receptors in the synaptic transmission of trigeminovascular neurons in trigeminal subnucleus caudalis. Extracellular single-unit recording of trigeminovascular neurons driven from dura or the superior sagittal sinus was made with a central barrel of seven-barrel micropipette. DL-2 amino-5 phosphonovaleric acid, N-methyl-D-aspartic acid (NMDA) receptor antagonist, produced a reversible inhibition of mechanical-evoked responses in 10 of 12 examined trigeminovascular neurons. The maximal inhibition was 59 ± 5 % of the control. However, CNQX did not affect trigeminovascular neuronal responses. Substance P also facilitated NMDA-evoked responses in 8 of 10 examined trigeminovascular neurons. The maximal facilitation was 153 ± 13 % of the control. These results imply that the NMDA receptor has a major role in the transmission of vascular headache (migraine) in trigeminovascular neurons and substance P also seems to be involved in maintenance migraine symptom.