大鼠脊髓GABAA受体在乙酯羟孕双酮抗伤害性效应中的作用

目的 探讨脊髓γ氨基丁酸A(GABAA)受体在乙酯羟孕双酮抗伤害性效应中的作用.方法 雄性Wistar大鼠,体重176～181 g,经L2,3行蛛网膜下腔置管.取置管成功的大鼠27只,随机分为4组:荷包牡丹碱0.01 pmol组(Ⅰ组,n=9)、0.1 pmol组(Ⅱ组,n=7)、1 pmol组(Ⅲ组,n=5)和10pmol组(Ⅳ组,n=6).采用电刺激法测定大鼠颈部和尾部痛阈,记录诱发尾部和颈部伤害性反应的最小电流,测定3次,间隔5 min,取其平均值作为基础痛阈(TH1).腹腔注射乙酯羟孕双酮1 mg/kg,5min后测定痛阈(TH2).经蛛网膜下腔导管注入重比重荷包牡丹碱溶液(溶于5 μl 6%葡萄糖溶液),5min后测定痛阈(TH3).结果 与TH1比较,各组颈部TH2和TH3、尾部TH2和Ⅰ组尾部TH3升高(P<0.05);与TH2比较,Ⅱ组～Ⅳ组尾部TH3降低(P<0.05),各组颈部TH3,差异无统计学意义(P0.05).结论 乙酯羟孕双酮可通过激活脊髓GABAA受体产生抗伤害性效应.

Role of spinal GABAA receptor in antinociceptive effect of alphadolone in rats

Objective To investigate the role of spinal GABAA receptor in the antinociceptive effect of. alphadolone in rats. Methods Male Wistsr rats weighing 176-181 g were studied. A catheter was inserted into suharachnoid space via L2,3. Twenty-seven rats successfully catheterized were randomly divided into 4 groups: bicuculline 0.01 pmol group (Ⅰ , n = 9), bicuculline 0.1 pmol group (Ⅱ, n = 7), bicuculline 1 pmol group (Ⅲ, n = 5) and bicuculline 10 pmol group (Ⅳ, n = 6) .The pain threshold in the neck and tail was measured using electrical stimulation. The minimum current of antinociceptive effects caused by stimulating the tail and neck were recorded (3 times every 5 min ) and the mean value was calculated and defined as the baseline value (TH1 ). Alphadolone 1.0mg/kg was then injected intraperitoneally and 5 min later the pain threshold (TH2) was measured. Hyperbaric bicuculline (in 6% glucose 5 μl) was then injected through the catheter into the]umber region of the subarachnoid space and 5 min later the pain threshold (TH3 ) Was measured. Results TH2 and TH3 in the neck and TH2 in the tail in each group and TH3 in the tail in group Ⅰ were significantly higher than TH1 ( P < 0.05). There were no significant differences in TH3 in the neck between all the groups ( P 0.05), while TH3 in the tail in group Ⅱ-Ⅳ was significantly lower as compared with TH2 ( P <0.05). Conclusion Alphadolone may have antinocicepfive effect through activation of spinal GABAA receptor.