Fig 7.

Rats received microinjection of CCK-8(s) (0.06µg/µl) or dH20 into the RVM. Tactile allodynia of the face (A) and hindpaw (B), indicated by significant decreases in response thresholds, were measured at 15 min intervals for 2 hr following CCK-8(s) or dH20 injection. CCK-8(s) injection produced significant tactile allodynia of both the face (A) and hindpaws (B) that peaked at the 30–45 min time-point and returned towards baseline by 2 hr. Behavioral responses were not altered by dH20 injection. In addition, male rats received microinjection of CCK2-antagonist, YMO22 (0.5 ng/µl) or saline into the RVM 30 min after dural inflammation (C). YMO22 significantly attenuated facial (P = 0.028) and hindpaw (P = 0.0001) allodynia, as indicated by asterisks, when compared to the vehicle-treated group. Behavioral responses were not altered by YMO22 in rats treated with SIF (data not shown).