动物造模 z-bo 2020-09-10 394

　　Introduction: Peripheral nerve block is often used for postoperative pain and surgical anesthesia. The long-acting local anesthetic itself has an analgesic effect of 9-14 hours. If the block is performed in the morning and afternoon, the patient will usually report postoperative pain in the evening. The use of opioids can cause airway obstruction and reduce saturation. Ideally, on the first night after surgery, a single peripheral nerve block should provide analgesia. Many other local anesthetics are being studied to cure postoperative pain. The effectiveness of chronidine has been proven in many local anesthesia methods. However, the results of long-acting local anesthetics are not satisfactory. In some studies, adding chronidine to a long-acting anesthetic has no beneficial effect. Dexmedetomidine is a selective alpha-adrenergic receptor agonist. Previous studies have shown that the combination of dexmedetomidine and bupivacaine can prolong the sensory and motor block time in a rat model of sciatic nerve block. Studies have shown that local anesthetics can cause muscle necrosis, but it is believed that this damage may not have clinical significance when muscles are regenerating normally. Although the dose of local anesthesia is generally reliable for healthy people, patients with asymptomatic neuropathic diabetes or multiple sclerosis can certainly be neurotoxic. After taking pyridine, inflammatory mediators increase. Studies have shown that compared with bupivacaine alone, adding dexmedetomidine to bupivacaine for 24 hours can significantly reduce peripheral inflammation. The same study found that the value of peripheral nerve inflammation at 24 hours was higher than that of the bupivacaine saline control group alone. The level of neuroinflammation in the bupivacaine and dexmedetomidine treatment group and the dexmedetomidine only treatment group was similar to the normal saline treatment group. As mentioned in previous studies, the use of dexmedetomidine to reduce peripheral neuritis is due to the reduction of pro-inflammatory products of healing immune cells and the increase of anti-inflammatory cytokines at the wound site. Under consideration. It is very important to determine the functional state of nerves. One way to assess the function of nerve repair or conduction disorders is to perform electrophysiological measurements. The electrocardiogram is a common method for clinical and basic research of in vivo and in vitro functional neurological research. It has a wide range of uses in electrical diagnosis of animal models and evaluation of peripheral nerve damage to the sciatic nerve. Studies have shown that after end-to-end repair of incision nerves, the use of hyaluronic acid filled silicon tubes has a positive effect on the incubation period and CMAP, and has a positive effect on axon regeneration. CMAP is usually an important parameter indicating nerve regeneration and innervation time. Studies have shown that stimulating single-fiber myocardial contrast (SSFEMG) is a more sensitive electrophysiological method for detecting neuromuscular block in weak muscles and acute organophosphate-infected rats. These EMG studies show that the use of EMG methods can indicate nerve healing and nerve damage. In our study, ECG was used to measure the effect of dexmedetomidine injection on nerve conduction. Pain relief, histopathology and electrocardiogram were performed to evaluate the effect of dexmedetomidine on the sciatic nerve of rats.

　　Method: Lower spinal cord injection: After weighing the rat, anesthetize with 2.5% isoflurane. In the correct supine position, use 2.5% isoflurane through a mask to maintain anesthesia. Make a lateral incision in the hind limb to receive the injection. The superficial myocardium is separated and the sciatic nerve is exposed at the proximal end of the bifurcation. After exposure of the sciatic nerve, group D (n = 7) was injected with dexmedetomidine 40μg/kg into the perineural space, and group S was injected with 40μg/kg normal saline. 30 GPPD syringe for injection. In group E (n = 2), only the sciatic nerve was exposed and sutured again. Record the injection time. During skin preparation, a non-absorbable suture under the skin is used to mark the myocardium of the biceps femoris muscle corresponding to the injection site to determine where to collect nerve samples. The suture was not placed around the nerve, nor did it touch the nerve. After injection, the incision was sutured. The isoflurane anesthesia was interrupted, the duration of anesthesia was recorded, and the rat was placed in a cage on its back. The time it takes the rat to return to the prone position is then recorded as the return to the righting reflex (RORR).

　　PAW Delayed Evacuation (PWL) test: After the rat returns to the lying position, put the only painkiller on the sole of the foot, and then perform the PWL test. The light source is used as an analgesic heater. After turning on the light source, the temperature of the corresponding point on the mouse foot reaches 30°C, wait 5 minutes, and then move the mouse foot to the corresponding point. Repeat this process with your left and right feet. From the beginning of the experiment to the end of the experiment (6.00-18.00h), the rats with no signs of neurological abnormality were raised in a light and dark environment for 12 hours. Before surgery, conduct neurobehavioral monitoring for 1 hour and 3 days every day. After the operation and injection of the rat, PWL measurement was performed every 30 minutes, and then the operation was performed on the left and right feet. The neurobehavior of all rats was monitored for 210 minutes. During this period, hind limb movement was evaluated every 30 minutes. When rats with dyskinesia (motor score = 1), normal foot position, or no dyskinesia (motor score = 0) return to basic sensory and motor values, they are returned to the cage. PWL measurements of both feet were performed 5 times every morning until the nerve was removed, starting from the morning after the injection, and then the rat nerve was removed at the injection site. The daily PWL value is the average of these measurements.

　　Electrophysiological study: After anesthetizing the rat with 2.5% isoflurane, the rat’s tail was fixed on the workbench. Place the needle electrode in the peroneal abdominal muscle and stimulate the sciatic nerve 10 times with an appropriate electrode located near the hip joint. Record the complex muscle activity potential (CMAP) between the peak value of the left and right sciatic nerve and the distal motor latency. The electrophysiological study uses an electromyography system and the software program Labchart 7 to evaluate the measurement results. The same operation was performed before the sciatic nerve injection and 14 days after the sciatic nerve injection, and samples were taken from the sciatic nerve and the results were compared. Histopathological study: On the 14th day, the rats were anesthetized with isoflurane for the first electrophysiological study, the sciatic nerve was injected with drugs, and then the rats were anesthetized with isoflurane again for the electrophysiological study. Has been completed. Make an anterior incision in the right hind limb, find the marked suture, and take a 1.5 cm long sciatic nerve sample from the corresponding area. Repeat for the left hind limb. The nerve sample was fixed with 2.5% glyceraldehyde for 3 days and then embedded in a paraffin block to form a 5 μm cross section. These samples were stained with eosin and evaluated. Confirmed as follows: inflammation around the sciatic nerve (0=no inflammation, 1=mild edema and/or inflammation of small lesions, 2=moderate edema and/or local extensive inflammation, 3=moderately diffuse area of hydrops and/ Or inflammation, local nerve damage is found) (0 = no damage, 1 = 1-2% damage to axons or myelin sheath, 2 = 2-5% damage to axons or myelin sheath, 3 = 5 upper axons or Myelin sheath) damage. After removing the sciatic nerve, the rats were euthanized by cervical dislocation. Results: When comparing the anesthesia time during the injection of rats, there is no statistical significance. Comparing the RORR value of each group of rats, we found that the differences between the groups are statistically significant. Comparing the two groups respectively, we found that the RORR value of group D is statistically significantly different from the other two groups. Compared with the other two groups, RORR value is longer. Group D: When comparing the PWL value of the right hind limb of the rat with the standard value, the PWL value was lower than the standard value at 30 minutes after the administration, and higher than the standard value at 210 minutes. There is no statistically significant difference between the 60 minutes, 90 minutes, 120 minutes, 150 minutes and 180 minutes measurements. The PWL value of the left hind limb of the rat was compared with the baseline value, and there was no significant difference at 60, 90, 120, 150, 180 and 210 minutes. Compared with the basic value, the PWL value of the right hind limb of rats was not statistically different from the basic value on Days 1, 8, 9, and 14, while the PWL values at other times were statistically longer. When the PWL value of the left hind limb of the rat was compared with the basic value, it was found that the difference between the measured values of 4 to 6 days, 9 to 12 days, and 14 days was statistically significant and longer than the basic value. .. No rats in group D showed dyskinesia. S group: The PWL value of the right hind limb of the rat was compared with the basic value. There was no statistically significant difference between 30 minutes, 60 minutes, 90 minutes, 120 minutes, 150 minutes, 180 minutes and 210 minutes. Yes. At 30, 60, 90, 120, 150, 180 and 210 minutes, there was no significant difference between the PWL of the rat's left hind limb and the baseline value. When comparing the PWL value of the right hind limb of the rat with the basic value, the difference is large between 4 to 7 days, 10 days, 11 days and 14 days, and it takes some time to compare with the basic value. The PWL value of the left hind limb of the rat was compared with the basic value. From the 3rd day to the 14th day, the difference was statistically significant, which was longer than the basic value. The rats in the S group had no movement disorders. Group E: The PWL value of the right hind limb of the rat was compared with the baseline value, and there was no statistical difference at 30, 60, 90, 120, 150, 180 and 210 minutes. At 30, 60, 90, 120, 150, 180 and 210 minutes, there was no significant difference between the PWL of the rat's left hind limb and the baseline value. The PWL value of the right hind limb of the rat was compared with the baseline value, and the difference was not statistically significant from day 1 to day 14. When the PWL value of the left hind limb of the rat was compared with the baseline value, the difference was not statistically significant on day 1-14. The rats in group E have no movement disorders. The histopathological comparison of the right sciatic nerve in rats showed that there was no significant difference in inflammation and local nerve damage in each group. The histopathological comparison of left sciatic nerve in each group showed that inflammation and local nerve damage in each group were not statistically significant. Comparing the pathological results of left and right nerve tissues in group D, the difference between inflammation and local nerve injury was not statistically significant.

　　Comparing the histopathological results of the left and right sciatic nerves in the S group, the difference between inflammation and local nerve damage was not statistically significant. Comparing the histopathological results of left and right sciatic nerve in group E, there was no significant difference between inflammation and local nerve injury. Comparing the CMAP and incubation period before and after injection in the D, S and E groups, the difference in CMAP value after injection was statistically significant. The difference in delay value is not statistically significant. There is a statistically significant difference in CMAP measurement after injection between group D and group S. Comparing the CMAP measurement results of S group and E group after injection, the difference between the two groups was not statistically significant. Comparing the pre-injection and incubation period of group D, group S and group E, the difference was not statistically significant. There were statistical differences in the CMAP value of group D before and after injection. Before and after injection, there was no statistical difference in CMAP value between S group and E group. Conclusion: Injecting dexmedetomidine into the right peripheral bone of rats can increase the pwl value by 210 minutes, and the RRRR reflex duration of rats after dexmedetomidine injection is significantly prolonged. Injection of dexmedetomidine around the sciatic nerve did not cause a statistically significant increase in peri-neural inflammation or local nerve damage; however, 14 days after injection of dexmedetomidine to the right sciatic nerve around the nerve. In addition, the CMAP value is significantly reduced.