【摘要】 电针镇痛能被吗啡受体拮抗剂所对抗,被认为是内源性吗啡样物质参与针刺镇痛的有力证据。给大鼠皮下注射吗啡受体拮抗剂纳洛酮或纳曲酮 1mg/kg, 可以对抗低频和中频(2和15Hz)电针的镇痛效应,但不能对抗高频(100Hz)电针镇痛效应。增加纳洛酮剂量至20mg/kg才能部分对抗 100Hz电针镇痛。根据不同剂量纳洛酮(0.25—20mg/kg)对抗不同频率电针镇痛的剂量效应曲线,求得对2,15和100Hz电针镇痛产生50％翻转作用的纳洛酮剂量分别为 0.53,1.02和 24mg/kg。2—15Hz变频电针的镇痛作用也需用大剂量纳洛酮(20mg/kg)才能阻断。实验表明,在三种频率下,改变电针刺激强度(1,2,3V)并不影响纳洛酮翻转电针镇痛的百分数。以上结果表明,纳洛酮翻转电针镇痛的程度决定于电针的频率,不同频率的电针刺激可能在中枢神经系统中释放出不同的内源性吗啡样物质而发挥镇痛作用。更多还原

【Abstract】 Antagonism of the analgesic effect of electroacupuncture (EA) by opioid anta-gonist naloxone has been regarded as strong evidence for the participation ofendogenous opioids in EA analgesia. We found in the present study that subcu-taneous injection of opioid antagonist naloxone or naltrexone, 1 mg/kg, was capableof reversing low and medium frequency (2, 15Hz) EA analgesia, but not highfrequency (100 Hz) EA effect which could only be partially blocked by 20 mg/kgof naloxone. From the dose-response curve obtained by 0. 25-20 mg/kg of naloxonethe doses needed for 50% reversal of 2, 15 and 100 Hz fixed frequency EA analgesiawere calculated to be 0.53, 1.02 and 24 mg/kg respectively. When a changingfrequency (2-15 Hz, 12 cycles per minute) was used, the analgesic effect couldonly be partially blocked by a large dose of naloxone (100μg intracerebroventri-cularly, or 20 mg/kg subcutaneously). Under either of the afore-mentioned fre-quencies, changes in the intensity of EA stimulation (1, 2, 3V) exhibited little effecton naloxone reversibility of EA effect. The results indicate that the frequency of EA stimulation seems to be thecardinal factor in determining the degree of reversal of EA analgesia by naloxoneand that different kinds of endogenous opioids might have been released in thecentral nervous system by EA stimulation of different frequencies.更多还原