摘要BACKGROUND: Scorpion venom from Buthus martensii Karsch is a kind of protein toxin secreted by scorpion tail. According to records of Pen-ts'ao Kan-mu, the dried scorpion's body and tail are used as medicine,which mainly treating rheumatism numbness, pain and convulsion. Some researches consider that scorpion toxin is the main pharmacological active component of the dried scorpion, and it has 4 times stronger analgesic effect on somatic pain than morphine.OBJECTIVE: To observe the interventional effect of scorpion venom of Buthus martensii Karsch analgesic active peptide on somatic pain.DESIGN: A randomized and controlled trial.SETTING: Department of Physiology, Shenyang Medical College.MATERIALS: Totally 80 Wistar rats (provided by Animal Center of Shenyang Medical College), male and female in half, aged 3 to 4 months, weighed 250 to 350 g, were used in this trial. They were randomly divided into 4 groups: experimental group, control group, morphine group and naloxone group, with 20 in each group. Analgesia active peptide from buthus martensii karsch venom (provided by Biochemical Department of Shenyang Pharmaceutical University, 1 mL/dosage), morphine (produced by Shanghai First Pharmaceutical Manufacturing Plant), naloxone (opium acceptor inhibitor, American Sigma Corporation), AT-AC-350 data-processing machine (Nihon Kohden Corporation), X-Y recording instrument (Nihon Kohden Corporation).METHODS: The experiment was conducted in the Department of Physiology, Shenyang Medical College from July 2003 to July 2005. ① After all the animals were anesthetized, common peroneal nerve is dissected and ligated at middle part. Posterior nucleus group of thalamus (PO) and the tail nuclear were oriented according to G. Paxino rat brain three-dimensional orientation atlas. Glass micro electrode was inserted into PO as guiding electrode, connected with ATAC-350 data-processing machine and X-Y recording instrument,to record the unit evoked potential of PO, taking the evoked potential discharge of the common peroneal nerve of PO as the somatic pain index.② Single square-wave stimulation of intensity 17-19 volt, wave wide 0.2 ms, time delay 20 ms was exerted on common peroneal nerve. The time interval was 5 minutes. X-Y recording instrument was used to draw the graph. 0.002 mg scorpion venom analgesic active peptide was injected into the rats of the experimental group; 0.002 mg normal saline was injected into the rats of the control group through caudate nucleus; 0.002 mg morphine was injected into the rats of morphine group through caudate nucleus; 1.0 mg/kg naloxone was intraperitoneally into the rats of naloxone group, then 0.002 mg scorpion venom was injected into the rats of control group through caudate nucleus. Changes of evoked potential of PO of 3 groups were observed. ③After experiment, 1 μA direct current was given to the guiding electrode and micro electrode , and it lasted for 5 minutes. Pontamine sky blue was used to label the peak of electrode by electrophoresis. Brain tissue was soaked in formalin for 1 week then sliced into 1.0 to 1.5 mm sections. Electrode was orientated according to blue spots. Compared with G. Parino rat brain three-dimensional orientation atlas, we confirmed if the electrode orientation is consistent with PO orientation of G. Parino rat brain three-dimensional orientation atlas.MAIN OUTCOME MEASURES: Changes of the evoked potential of PO in each group.RESULTS: Totally 80 Wistar rats were enrolled in this experiment. Four rats in the experimental group and two in the morphine group died of overdose of anesthesia, and finally 74 rats entered the stage of result analysis. The inhibitory action time of evoked potential of PO has no statistical difference in between experiment group and morphine group (P ＞ 0.05). The whole inhibitory action time, timeof initiate recovery and time of complete recovery of PO of experiment group were longer than those in the morphine group [(45±0.7), (50±9.2), (65±8.1); (35±7.8), (40±8.9), (50±7.6) min, P ＜ 0.05].The change of evoked potential of PO was not obviously in the control group and naloxone group (P ＞ 0.05), and the above-mentioned 4 indexes were nearly 0.CONCLUSION: Scorpion venom possesses obviously inhibitory effect on somatic pain, and its inhibitory effect is stronger than that of the same dosage and concentration of morphine. Scorpion venom exerts analgesic effect on somatic pain through opium acceptor.