Fig 3.

Rats received dural administration of IM or SIF and also received either sumatriptan (0.6 mg/kg, s.c.), naproxen (100 mg/kg, s.c.), or saline. Animals were injected systemically either 10 min prior to the dural administrations or 0.5, 1.5 or 2.5 hrs after dural administration. Pretreatment with sumatriptan or with naproxen prevented the development of tactile allodynia of the face (A) or hindpaws (B), indicated by significant (P < 0.05) reductions in normalized allodynic responses. Administration of sumatriptan or naproxen 0.5 hr after dural inflammation abolished facial and hindpaw indications of tactile allodynia. In contrast, the administration of sumatriptan 1.5 and 2.5 hrs after IM or naproxen 2.5 hrs after IM did not significantly alter the withdrawal thresholds to light tactile stimuli applied to the face (A) or hindpaws (B). Asterisks indicate significant (P < 0.05) differences from the corresponding vehicle-treated group within each experiment. Animals treated with SIF and then treated with either saline, sumatriptan or naproxen did not demonstrate any evidence of tactile allodynia of the face or hindpaws (data not shown).