Study On The Mechanism Of Analgesia Induced By Triterpenoid Saponins From Stauntonia Chinensis In Cerebral Cortex Of Mice By Increasing Inhibitory Synaptic Response

Pain is a kind of unpleasant feeling,which may occur in many diseases.It often causes patients to suffer mental and physical pain,which seriously affects the work and life of patients.The analgesics used in clinic have strong toxic and side effects,so it is necessary to develop a new analgesic drug with high efficiency,little side effects and no addiction.Stauntonia chinensis DC.is a traditional Chinese medicine,which is often used for anti-inflammatory and analgesic effects.Its tablets,injections and other preparations have been widely used in clinical practice.Previous studies have shown that the effective analgesic ingredient of Stauntonia chinensis DC.is triterpenoid saponins.The brain is the most advanced part of the nervous system.It receives external stimuli and transmits signals through neurons.The generation of pain is closely related to the brain.At present,the role of triterpenoid saponins from Stauntonia chinensis(TSS,for short)in the central nervous system is not clear.Therefore,studying the mechanism of action of TSS in the central nervous system is of great significance for the study of new analgesic drugs.The purpose of this study is to investigate the specific effects and mechanisms of TSS in the central nervous system,and to further explore the analgesic effect of TSS.We selected primary cultured brain cortical neurons of mice,and after incubation with TSS solution,used patch clamp technique to record mEPSC,mIPSC,eEPSC and eIPSC of neurons,we found that TSS can increase spontaneous inhibitory synaptic responses.Testing the time and concentration dependence of TSS,10 ?g/ml TSS incubation for 60 minutes was selected as the experimental conditions for the later experiment.Based on the above results,glutamic acid decarboxylase 65,a marker of inhibitory synapses,was selected for immunofluorescence staining to determine the density and area of inhibitory synapses in brain neurons incubated with TSS.It was found that TSS had no effect on the number and size of inhibitory synapses.Recording the readily releasable pool of neurons after incubation under the stimulation of hypertonic solution.It was found that TSS had no effect on the amount of releasable vesicles in inhibited presynaptic neurons.The number of GABAA receptors in inhibited postsynaptic neurons after incubation with TSS was measured by fluorescence quantitative RTPCR,and TSS was found to have no effect on the number of receptors.GABA currents were recorded under stimulation of GABA solution.The results showed that TSS enhanced the activity of GABA receptors in inhibited postsynaptic membrane.Then exploring the effective time for TSS analgesia.It was found that the effect of TSS could last at least 8 hours.Through the series of experiments,we concluded that TSS significantly increased the spontaneous inhibitory synaptic response in cerebral cortical neurons,mainly by continuously increasing the presynaptic membrane vesicle release frequency and posterior membrane at rest.The GABA receptor activity acts as an analgesic effect and this effect lasts for at least 8 hours.This conclusion further clarifies the mechanism of action of TSS in the central nervous system,suggesting that TSS may be a candidate for new analgesics.