Figure 2.

nVNS and sumatriptan inhibit trigeminal nociception mediated by nitric oxide in sensitized animals. The average nocifensive head withdrawal response ±SEM of 5 applications to each side to mechanical stimuli are reported. Some animals were left untreated (Naïve), some were injected with saline in the trapezius (Saline) and exposed to the nitric oxide donor sodium nitroprusside (SNP), while others were injected with complete Freund's adjuvant 8 days prior to exposure to SNP (M+SNP) and nociceptive responses determined at 2 h, 3 h, and 1 day post SNP exposure. Some of the M+SNP animals were treated with nVNS or sumatriptan and nociception measured 1 h and 1 day post treatment. *P < 0.05 when compared to Naïve while #P < 0.05 compared to M+SNP.