| Background:Trigeminal Neuralgia is a kind of oral-maxillofacial disease,characterized with the recurrent attack of paroxysmal excruciating pains in the distributional area of unilateral facial trigeminal nerves.The pathogenic mechanism of Trigeminal Neuralgia remains partly uncertain,and it is treated with non-surgical and surgical methods.In the non-surgical treatment,the drug therapy is preferred,for most patients,the drug therapy has a poor effect or severe side effects,the acupuncture,physiotherapy and injection therapy are flawed by a uncertain effect and a high probability of recurrence,the patients who choose the surgical treatment have to under a great risk of surgical complications.Tt cannot be perfectly treated clinically.Botulinum Toxin Type A is widely used in the domain of muscle spasm,facial cosmetology and rhytidectomy and treatment of head and facial pain.In recent years,there have been some foreign and domestic reports that,Botulinum Toxin Type A has a curative effect on treating the Trigeminal Neuralgia,showing the advantage of micro-invasiveness,simple operation and high efficiency,but its underlying mechanism remained unclear.For this reason,we have built a Trigeminal Neuralgia animal model and applied the botulinum toxin to simulate the clinical treatment,in order to reveal its curative effect on Trigeminal Neuralgia and its underlying mechanism.Objective:to observe the curative effect of Botulinum Toxin Type A on the rat model with Trigeminal Neuralgia,and to explore the mechanism of its effect.Method : experiment 1: Talcum powder suspension with a concentration of 30% was injected by 0.3ml to the area of facial infraorbital foramen of the rats in 10 rats,or 0.9%normal saline was injected by 0.3 ml to the same position of rats in another 10 rats.An behavioral observation and mechanical withdrawal threshold measurement were carried out to the animals in both groups on day 3 before injection and on day 3 and week 1,2,4 and 8after injection.20 healthy rats were prepared into animal model.Ten rats in experiment group were subcutaneously injected with 0.3 ml of 10 U/ml Botulinum Toxin Type A in the facial pain-sensitive area at the same side where surgery was performed,another 10 rats were only injected with the same dosage of normal saline in the according facial position as a control,An behavioral observation and mechanical withdrawal threshold measurement were carriedout to the animals in both groups on the day of injection and on day 3 and week 1,2,4 and 8after injection.48 healthy rats were prepared into Trigeminal Neuralgia animal model.24 rats were subcutaneously injected with 0.3 ml of 10 U/ml type-A botulinum toxin in the facial pain-sensitive area at the same side where surgery was performed as an experiment group,another 24 rats were only injected with the same dosage of normal saline in the according facial position as a control,4 animals from the experiment group and from the control group were killed on the day of injection,on day 3,week 1,2,4 and 8 after injection,their medulla tissue was taken for immunohistochemical detection that detects the change in p substance in skull and in β-endorphin(β-EP).Results:1.the mechanical withdrawal threshold of rats in experiment group and control group was respectively 14.44±0.98 g and 14.30±1.01 g,the difference between two groups was not statistically significant.10 rats in experiment group were injected with talcum powder to the periphery of infraorbital nerve,three days later,a animal model of Trigeminal Neuralgia was successfully built.The rats developed behaviors of face scratching,attack and withdrawal,the mechanical withdrawal threshold on day 3,week 1,2,4 and 8after injection was measured to be 4.39±0.82 g、3.24±0.70 g、3.60±0.64 g、4.19±0.75 g and 4.83±0.70 g,which were evidently reduced as compared to the mechanical withdrawal threshold before operation and of the control group,the differences were statistically significant(p<0.01).2.3 rats in the experiment group developed less behaviors of face scratching,attack and biting and a higher mechanical withdrawal threshold as compared to control group 3 days after injection of Botulinum Toxin Type A in the facial pain sensitive area,the difference in mechanical withdrawal threshold between two groups was not statistically significant(p>0.05).With the time passing after injection,the mechanical withdrawal threshold was evidently elevated,the difference was statistically significant as compared to control group(p<0.01),this significant difference sustained till week 8 after injection of botulinum toxin.3.The immunohistochemical detection found that the intracranial SP content was significantly reduced on week 1,2,4 and 8 after injection of botulinum toxin to 24 rats with Trigeminal Neuralgia,the difference between it and the control group was statistically significant(p < 0.01);the content of β-endorphin was significantly elevated,and the difference between it and the control group was statistically significant(p<0.01).Conclusion:1.a reliable animal model can be built by injecting the talcum powder to the periphery of infraorbital foramen.2.injection of Botulinum Toxin Type A has a curative effect on the animal model of rats with Trigeminal Neuralgia.3.the curative effect is realized by reducing the release of intracranial painful substance and increasing the synthesis of analgesic substance. |
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