本文以猫脊髓处的检验刺激所诱发的腓肠神经逆向 C 波大小作为判断初级传入 C 纤维突触前末梢兴奋性的指标。电针“环跳”及“阳陵泉”穴引起该逆向 C 波明显增大。表明初级传入 C 纤维突触前末梢发生了去极化。而荷包牡丹碱、纳络酮及 P 物质抗血清能明显地抑制此针刺效应。提示 GABA,内阿片肽及 P 物质均参与针刺突触前抑制的调节。
In our previous work, acupuncture induced inhibition of the nociceptive respons e to peripheral noxious stimulation at spinal level could be blocked by iontopho retic bicuculline(Bic), an antagonist for GABA A receptors, suggesting an invol vement of GABA in acupuncture induced segmental inhibition. However some report s declare that increase in GABA content in brain is not benefit to acupuncture ana lgesia. In this paper, the effects of intra cerebroventricular and intrathecal i njection (icv and ith) of Bic on acupuncture analgesia were further investigated by tail flick latency tests in rats. There were 6～8 rats in each group. Th e results were as follows: 1. After icv GABA in dose of 0, 125, 250, 500 and 1000 μg /5 μL, the pain thre shold (PT) were raised to 102%, 108%, 128%, 136%, and 157% of the basal control value respectively. It indic ates that icv GABA could produce dose dependent analgesic effect. 2. After icv Bic at the dose of 10 and 20 μg /5 μL, icv GABA (500 μg /5 μL) induced analgesic effect lowered from 136.24±1.96% to 111.8±0.98% and 111.25±0.65% separately. It means that icv GABA induced analgesic effect is significantly blocked by preinjection of Bic. 3. After electro acupuncture at bilateral "Ciliao" (BL 32) points (50 Hz, 1～2 mA) for 10 minutes, PT were raised to 142.50±2.10% without any treatment and 1 4 3.72±2.04% with pretreatment of saline. When pretreated with icv Bic at doses o f 10 and 20 μg /5 μL, acupuncture analgesic effects (PT still raised to 141.74 ±1.54% and 146.71±1.85%) showed no significant reduction. It indicates tha t GABA in brain might not be involved in acupuncture analgesia. 4. After electro acupuncture at bilateral "Ciliao"(BL 32), PT were raised to 139.56±1.21% with ith saline and to 138.96±1.43% pretreated with ith Bic 5 μg /10 μL. When pretreated with ith Bic at doses of 10 and 20 μg /10 μL, PT wer e raised to 126.55±1.73% and 114.52±1.68% respectively, indicating the signifi cant reduction of acupuncture analgesia. It means that GABA mig
In our previous work, acupuncture induced elevation of pain threshold could not be blocked by intra cerebroventricular injection of bicuculline, an antagonist f or GABA A receptors, suggesting that GABA in brain might not be involved in acup uncture analgesia, at least might not be mediated by activation of GABA A recept ors. In this paper, the effects of intra cerebroventricular and intrathecal inj e ction (icv and ith) of CGP 55845, a potent and selective antagonist against GABA B receptor, on acupuncture analgesia were further investigated by tail flick la tency tests in rats. There were 6～8 rats in each group. The results were as f ollows: 1. After icv and ith baclofen(Bac), an agonist of GABA B receptor at doses of 0. 0 25 μg /5 μL and 0.25 μg /10 μL(+5 μL saline) , pain threshold (PT) were rai sed to 125.11±1.94% and 128.63± 0.93% of the basal control value respective ly. While subcutaneous injection of Bac, 50 μg /kg was needed to produce significant analgesic effect (PT raised to 130.94±1.62%). It indicates that activation of GABA B receptor co uld produce analgesic effects mainly in the central nervous system. 2. After icv CGP 55845 at doses of 0.5, 5.0, and 50 ng /5 μL, icv Bac (2.5 μg /5 μL) induced analgesic effect (PT raised to 136.24±1.96%) was blocked by 3 7.4%, 77.0% and 75.1% respectively (PT raised to 130.43±1.72%, 111.8±0.98% and 111.25±0.65%). It means that icv Bac induced analgesic effect could be signif icantly blocked by pretreatment of icv CGP 55845. 3. After electroacupuncture at bilateral "Ciliao"(BL 32) points (50 Hz, 1～2 mA) for 10 minutes, PT were raised to 142.50±2.10 % without treatment, 143.74±2.0 4% with pretreatment of saline and 142.47±1.18% with pre icv CGP 55845 at dose s of 0.5 ng/5 μL. When pretreated with icv CGP 55845 at doses of 5 and 50 ng/ 5 μL, acupuncture analgesic effects were significantly blocked by 73.7% and 71. 6% (PT raised to 111.19±1.20% and 112.09±1.12%). It indicates that GABA in brai n might be involved in acupuncture analgesia ma
