| Objective To investigate whether there are different effects of electric stimulation of vagus nerve, peripheral nerve (sciatic nerve and trigeminal nerve), and motor cortex on Pentylenetetrazol induced convulsion in rats.Methods The vagus nerve and sciatic nerve were exposed in rats. Then the stimulation electrodes were placed on the vagus nerve, sciatic nerve, trigeminal nerve, and motor cortex, respectively. After electric stimulation, PTZ (50mg/kg) were intraperitoneally injected into the rats. The pattern and latency of the convulsion seizure were observed and recorded.Results1.Ⅰ-Ⅴgrade convulsion seizure (Racine's grade) was present in 90 percent of rats in the control group after the injection of PTZ; however, this intensity was reduced toⅠ-Ⅲgrade differentially in all the rats by electric stimulation of the vagus nerve or peripheral nerve. Moreover, in the group of rats which were stimulated at motor cortex, there was completely no convulsion. On the other hand, when pathological changes appeared in cortex or hippocampus (i.e. epileptic model was set up by 7w stimulation), the same stimulation of motor cortex was not able to inhibit the convulsion seizure induced by injection of PTZ and all those rats showedⅣ-Ⅴgrade seizure.2. Comparison between VNS,TNS,SNS,MCS(physiological)group and contrast group,there were significant changes(P<0.05);what'more,there were no significant changes in the pattern and latency of the convulsion seizure of VNS,TNS,SNS,MCS(physiological) group (P>0.05); however, comparison on the rate of convulsion seizure and intension is obvious (P<0.05). Moreover, there were no significant changes between MCS(pathological)and contrast group (P>0.05).Conclusion1. In physiological condition, all of the four types of stimulation differentially reduced intensity of convulsion seizure triggered by PTZ injection and motor cortex stimulation has the best effect. However, when rats were in pathological status and epileptic nidus appeared in their brains, stimulation of motor cortex has no effect on PTZ induced convulsion seizure.2. Outer stimulation may arouse any endogenesis reaction on the brain, but the reaction might play two-tier role, not only appear reaction, but confront the stimulation. What'more, the reaction is more limited then droug. During experiment, we found an interesting phenomenon. When rat represent seizure persistence, antipsychotic injected could stop the state; however, any electrical stimulation didn't Hay an role on the state, and some rats died due to endless seizure.3. Electric stimulation of motor cortex can induced convulsion in rats differentially along with current intention,include local and all-around convulsion.However, VNS,TNS,SNS don't present any convulsion.4. It is supposed that the effect is limited in all therapy methods of epilepsy include VNS,TNS,magnetism stimulation in brain,thalamencephalon placed electrode stimulation etc. Patients and doctors should not show high expectation to these methods, and the effect could not behave obviously than droug and operation. |
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