人参皂甙Rgl对炎性痛大鼠吗啡耐受时脊髓背角细胞凋亡的影响

Effects of ginsenoside Rgl on apoptosis in spinal dorsal horn in development of morphine tolerance in rats with arthritis

目的探讨人参皂甙Rgl对炎性痛大鼠吗啡耐受时脊髓背角细胞凋亡的影响。方法雄性SD大鼠，体重280～320g，采用右踝关节腔内注射完全弗氏佐剂的方法制备炎性痛模型。取模型制备成功的24只大鼠，采用随机数字表法，将其随机分为4组（n=6）：生理盐水对照组（C组）、吗啡耐受组（M组）、人参皂甙Rgl组（G组）及吗啡复合人参皂甙Rgl组（MG组）。致炎后3d时M组、G组及MG组分别鞘内注射吗啡10μg、人参皂甙Rgl100μg及吗啡10μg＋人参皂甙Rgl100μg，C组给予等容量生理盐水，吗啡2次／d，人参皂甙Rgl1次／d，连续7d。分别于致炎前（T1）、鞘内给药前1d（T2）、给药1、3、5、7d（T3-6）时测定机械缩足阈值（PWT）。最后一次测定痛阈后处死大鼠，取L3-5，节段脊髓组织，采用TUNEL染色法测定细胞凋亡情况，计算脊髓背角细胞凋亡率。结果与，T1时比较，4组T2-6时PWT降低（P〈0．01）；与T2时比较，M组T3.4时PWT升高，G组和MG组T3-6时PWT升高（P〈0．05）；与C组比较，M组和MG组PWT和脊髓背角细胞凋亡率升高（P〈0．05），G组上述指标差异无统计学意义（P〉0．05）；与M组比较，MG组PWT升高，脊髓背角细胞凋亡率降低（P〈0．05）。结论人参皂甙Rgl预防吗啡耐受形成的机制与降低炎性痛大鼠脊髓背角细胞凋亡有关。

Objective To investigate the effects of ginsenoside Rgl on apoptosis in spinal dorsal horn in development of morphine tolerance in rats with arthritis. Methods Twenty-four healthy male SD rats weighing 280-320 g in which intrathecal（IT） catheters were successfully implanted without complication were randomized into 4 groups （n = 6 each）： group normal saline （group C）; group morphine （group M）; group ginsenoside Rgl （group G） and group morphine ＋ ginsenoside Rgl （group MG）. Arthritis was induced with complete Freund adjuivant injected into the ankle joint of fight hind limb according to the method described by Butler et al in all 24 animals. Chronic morphine tolerance was induced by IT morphine 10 μg twice a day for 7 consecutive days in groups M and MG. Ginsenoside Rgl 100 μg was given IT once a day for 7 consecutive days in groups G and MG. Paw withdrawal threshold to mechanical stimulation with von Frey filaments （MWT） was measured before induction of arthritis （T1 , baseline）, and IT drug administration （T2） and at day 1, 3, 5, 7 （T3-6） after IT administration. The rats were sacrificed after last MWT measurement and their lumbar segments of the spinal cord （L3-5） were removed for detection of apoptosis in the spinal dorsal horn by TUNEL. Results MWT was significantly decreased after induction of arthritis at T2-6 compared with the baseline value before arthritis at T1 in all 4 groups. In group M IT morphine significantly increased MWT at T3,4 compared with the baseline at T2 but the MWT was decreasing at Ts,6 indicative of development of morphine tolerance. In group MG, addition of ginsenoside Rgl to IT morphine significantly attenuate the decrease in MWT at T5, 6 -The number of apoptotic cells in spinal dorsal horn was significantly higher in groups M and MG than in group C, but was significantly lower in group MG than in group M. Conclusion Ginsenoside Rgl can prevent the development of morphine tolerance in rats with arthritis by inhibiting apoptosis in spinal dorsal horn.