ABSTRACT
Objective To investigate the effects of intrathecal (IT) gabapentin on the analgesic efficacy of morphine in a rat model of incisional pain. Methods Forty-eight male SD rats in which IT catheters were successly inserted according to the method described by Yaksh were randomly divided into 6 groups ( n = 8 each): Ⅰ sham operation group, Ⅱ incisional pain group, Ⅲ GBP 50 μg group, Ⅳ morphine 2.5 μg group, Ⅴ morphine 5 μg group, and Ⅵ morphine 2.5 μg + gabapentin 50 μg group. In group Ⅰ , IT artificial cerebrospinal fluid (ACSF)10 μl was injected and then 1.4% isoflurane was inhaled for 5 min. IT ACSF 10 μl, gabapentin 50μg and morphine 2.5 and 5 μg were injected 30 min before the establishement of the model in group Ⅱ -Ⅴ respectively. Paw withdrawl threshold (PWT) to mechanical stimulation and paw withdrawal latency (PWL) to a thermal nociceptive stimulus were measured at 2 h after the establishement of the model. Results Compared with group Ⅰ , MWT was significantly decreased and TWL was significantly shortened in group Ⅱ , Ⅲ and Ⅳ ( P ＜ 0.05), but no significant change in MWT and TWL was found in group Ⅴ and Ⅵ (P＞0.05). Compared with group Ⅱ , MWT was significantly increased and TWL was significantly prolonged in group Ⅴ and Ⅵ (P ＜ 0.05), but no significant change in MWT and TWL was found in group Ⅲ and Ⅳ/ ( P ＞ 0.05). MWT was significantly decreased and TWL was significantly shortened in group Ⅲ and Ⅳ compared with group Ⅵ ( P ＜ 0.05). Conclusion IT gabapentin enhances the analgesic efficacy of morphine in a rat model of incisional pain.