Effect of preemptive analgesia with rofecoxib in a rat model of acute pain
- VernacularTitle:罗非昔布对急性痛大鼠的超前镇痛效应
- Author:
Ke MA
;
Zhongping LU
;
Wei JIANG
- Publication Type:Journal Article
- Keywords:
Cyclooxygenase inhibitors;
Spinal cord;
Sodium Channels;
Pain measurement
- From:
Chinese Journal of Anesthesiology
1994;0(01):-
- CountryChina
- Language:Chinese
-
Abstract:
Objective There are still different news on the preemptive analgesia. We aimed to investigate the preemptive analgesic effect of rofecoxib on the tetrodotoxin-resistant (TTX-R) sodium current in dorsal root ganglion (DRG) neurons m a rat model of acute pain. Methods Seventy-five male SD rats weighing 100-140 g were randomly divided into five groups with 15 animals in each group: (A) sham operation + placebo group; (B) operation control group received placebo orally before operation; (C) preoperatine rofecoxib group received oral rofecoxib 10mg?kg-1 h before operation; (D) and (E) postoperatire, rofecoxib group Ⅰ and Ⅱ received oral rofecoxib 10mg?kg immediately (D) and 1 h (E) after operation. Acute pain was produced by an 1 cm long incision in the plantar surface of the right hindpaw through skin, fascia and muscle. Pain threshold to mechanical stimulation with von Frey filament was measured before (baseline) and 2, 6,12, 48, 96 h after operation. The animals were killed by cervical dislocation before and 24, 48, 96 h after incision. DRGs at L3.5 on the operated side were isolated and minced. DRG neurons were isolated by digestion with collagenase Ⅰ A and trypsin TTX-R Na-current density in DRG neurons were measured by using whole-cell patch clamp technique. Results There was no significant change in pain threshold to mechanical stimulation and Na-current density in DRG neurons during the experiment in group A, The withdrawal threshold to mechanical stimuli was significantly decreased after operation compared to the baseline in the four groups ( B, C, D, E). The decrease in pain threshold was significantly less in group C,D,E than that m group B at 2, 6, 12, 24, 48 h after operation and was the least in group C Current density (pA/pF) was significantly increased at 24 h and 48 h after operation compared to baseline in group B, C, D, E. The increase in current density was significantly less in group C, D, E than in group B and was the least in group C.Conclusion Rofecoxib given before operation has preemptive analgesic effect in a rat model of acute pain. Stronger inhibition of TTX-R Na-current m DRG neurons may contribute to the underlying mechanism.
