A Study Of Analgesic Effect And Mechanism Of Crystal-8 From Zanthoxylum Nitidum(Roxb.)Dc.

5Objective: To study the analgesic effect of crystal-8 and observe the effect of intracrwbroventricular injection of crystal-8 on pain threshold; also we explored the relathionship between analgesic effect of crystal-8 and opiun acceptor, monoamine neural transmitter, haloperidol, scopolamine. Using the formalin painful model rats, we studied the mechanism of analagesic effect of crystal-8.Methods:1.analgesic effect of the crystal-8 Adopting acetic acid writhing and hot plate test in mice,the changes of the number of writhing,the latencies of paw licking after adiminstration were recorded. TheⅠandⅡphase pain were observed with the pain modle caused by formalin test;tail flick test was used to determinate the pain thresholds of mice.2.Initial studay of analgesic mechanism of the crystal-8 The tail-flick test was used to measure the change of pain threshold fowlling intracrwbroventricular (ICV) injection of crystal-8,also the influences of naloxone and reserpine, haloperidol, scopolamine to crystal-8 were evaluated by the tail-flick test. 3.Study of analgesic mechanism of the crystal-83.1 Building the formalin pain rat model We would adopt injecting the 5% formalin solution 100μl into the right paw of rats to made the pain model and reference Mestre grading score ways to assessment the model. The qualified experimental rats would enter the next step. We explored the pathological changes of the model rats by HE staining and Nissl staining, and the ultrastructural changes would be observed by the electron microscpy.3.2Relations between analgesic effect of the crystal-8 and NO, PGE2, MDA The contents of nitric oxide (NO), the malondialdehyde(MDA), and prostaglandin E2 ( PGE2) in the brain tissue were recorded by colorimetry.3.3Relations between analgesic effect of the crystal-8 and central neurotransmitter. We detected the content of monamine neural transmitter including NE, 5-TH,DA in the brain tissue with the pain model rats induced by formalin by Elisa.3.4 Effect of the crystal-8 on the expression of Fos in the brain of painful rats. Expriment detected the expression of c-fos gene in central tissue by using the method of immunohistochmistry.3.5 Effect of the crystal-8 on the expression ofβ-endorphine in the brain of painful rats. Hippocampus and thalamus were cut down and made into serial sections. The positive cells ofβ-endorphine expression were calculated in hippocampus and thalamus increased in high and low dose group,when compared with mode group.Results:1.Crystal-8 (15, 30, 60 mg·kg-1 ) could remarkly reduce the numbers of wrinting as wells as prolong the latencies of paw licking. crystal-8 had inhibitory effect onⅠandⅡphase pain in formalin test, also the fail-flick latencies were prolonged.2. It was found that pain threshold was increased significantly after injecting crystal-8 into the lateral cerebral ventricle of rats. Naloxone, haloperidol, and scopolamine had no effect on analagesic effect of crystal-8, but reserpin could reverese analgsic effect of crystal-8.3.There were obvious two phase nociceptive response after injecting formalin solution into rats. It showed that the rats had no pathological changes by HE staining and nissl staining,yet there was swelling in mitochondria of prerinuclear and cytoplasm in hippocampus and thalamus.4.Cystal-8 could obviously lowered contents of NO, MDA, PGE2 in the brain tissue.5.Cystal-8 could increase DA, 5-TH, yet decreased NE in the brain tissue significantly.6.Cystal-8 could restrain the c-fos gene expression of central tissue.7.After that cystal-8 was given to the rats,the expression ofβ-endorphine in hippocampus and thalamus increased in high and low dose group when compared with model group.Conclusions:1. The crystal-8 is shown to have excellent analgesic effect.2. The analgesic effect of crystal-8 may be related to the central mechanism; and the analgesic effect of crystal-8 to the thermal stimulation has effect on monoamine neural transmitter,while the analgesic effect has little effect on opium acceptor, DA acceptor, M acceptor.3. The site of analagesic action of crystal-8 may be in the central nervous system. It ,s mechanism of analagesic action may be related to reducing the NO, lipid peroxidtion,as well as inhibiting PGE2 production. 4. Crystal-8 adjusts pain through regulating the content of monamine neural transmitter of pain model rats.5.The analagesic effect of crystal-8 is probably associated with it,s effect on restraining the Fos expression of central tissue.6.The analgesic effect of crystal-8 has effect on the expression ofβ-endorphine, it may be related to the central mechanism.