The analgesic effect of intrathecal pergabalin and/or morphine on bone cancer pain in rats

Objective To evaluate the analgesic effect of intrathecal injection of pregabalin and/or morphine on bone cancer pain in rats.Methods Twenty rats were used to establish the models of bone cancer pain,and randomly divided into 4 groups (n =5 each):group A (20 μl normal saline was administered intrathecally) ; group B (30 μg pregabalin was administered intrathecally) ; group C (2 μg morphine was administered intrathecally) ; group D (30 μg pregabalin +2 μg morphine).The pain threshold at different time points (3rd,7th and 10th day after dosing) was measured.Results In group B,mechanical paw withdrawal reflex threshold (MWT) at each time point [3 d:25.1 g; 7 d:25.6 g; 10 d:24.9 g],and thermal withdrawal latency (TWL) [3 d:(5.3 ±0.2) s; 7 d:(5.2 ±0.8) s; 10 d:(5.2 ±-0.4) s] were significantly higher than in group A (P ＜ 0.05).In group C,MWT at each time point [3 d:27.8 g; 7 d:28.1 g; 10 d:28.7g],and TWL [3d:(5.8±0.5) s; 7 d:(5.9±0.7) s; 10 d:(5.8±0.4) s] were significantly higher than in groupA (P＜0.05).In group D,MWT [3 d:39.8 g;7d:40.2 g; 10d:41.1 g],and TWL [3 d:(9.8 ±0.7) s; 7 d:(9.7 ±0.2) s; 10 d:(10.0 ±0.2) s] were singnificantly higher than in groups B and C (P ＜ 0.05).Conclusion Pregabalin and/or morphine administrered intrathecally can raise the MWT and TWL,and produce a better analgesic effect in rat model of bone cancer pain. Key words: Pregabalin ;  Bone cancer pain ;  Intratheacal injection