Frankincense And Myrrh Alleviates Neuropathic Pain In Mice Via Inhibition Of TRPV1

Neuropathic pain is clinically of a refractory chronic pain disorder,and its high morbidity and low cure rate are increasingly subject to multidisciplinary attention both at home and abroad.In the mechanism of neuropathic pain,TRPs channel are widely concerned,especially TRPV1,which is mainly expressed on small diameter neurons of dorsal root ganglion and trigeminal ganglion,is thought to be particularly closely related to pain.It is a gated molecule of inflammation and pain pathways,and has an important role in neuropathic pain occurrence,development and process.TRPV1 is considered to be one of the most promising targets for the treatment of acute and chronic pain drug development.Frankincense and myrrh show a distinctive feature and good results in the treatment of pain,they are often used as a group of drugs in clinical,to obtain synergistic analgesic effect,but the mechanism of its analgesia is not clear.In order to reveal the analgesic mechanism of frankincense and myrrh,this paper established the chronic constriction injury(CCI)of mice,and observed the effects of a combined water extract of frankincense and myrrh(WFM)on CCI mice.And to explore the mechanism of WFM to inhibit neuropathic pain with TRPV1 target.Objective:To investigate the analgesic effect and related neural mechanisms of WFM in the model of neuropathic pain in mice.Methods:(1)C57BL/6 mice,male,6-8 weeks,8 rats were given WFM(7.5g/kg),before administration,3,4,5 hours 50? water bath soaking tail,record the time of the mouse flick.(2)16 mice were randomly divided into saline group(Saline)and WFM(7.5g/kg).The mice were given normal saline and WFM by intragastric administration before 3 hours,then capsaicin(3?g/mouse)was given to the mice.Record and count the number and time of mouse licking feet.(3)72 mice were randomly divided into 6 groups(12 in each group):? blank(naive)group:wild type mice(WT)+ vehicle(vehicle;? sham operation(sham)(CCI)mice:CCI WT mice+ distilled water;? CCI group:CCI WT mice + distilled water;? WFM-L group:CCI WT mice + WFM-L(WFM,1.5 g/kg/day);? WFM-H group:CCI WT mice + WFM-H(WFM,7.5 g/kg/day);? gabapentin(GBPT)group:CCI WT mice + GBPT(GBPT,0.2 g/kg/day).Each group of mice was fed with distilled water or WFM or gabapentin from day 7 for 10 days to the end of day 16,and the same group of mice were given the same volume per day.Operated by the same person.(4)6 groups mice were weighed on the 1st,3rd,5th,7th,10th,13th and 16th day after operation,then the mechanical withdrawal threshold(MWT)and the thermal withdrawal latency(TWL).(5)The expression of TRPV1 in mice was observed by mmunofluorescence staining,real-time quantitative polymerase chain reaction(q-PCR)and Western Blotting(P<0.05).(6)The DRG of mouse L4,5 and sacral were observed.The changes of TRPV1 physiological activity were observed by calcium ion imaging.Results:(1)The sensitivity of mice to nociceptive fever was significantly decreased,and the differences were significant at 3,4 and 5 hours compared with the control after administration with WFM.(2)The number and time of licking feet in capsaicin-induced mice were significantly lower than those in saline group(P<0.05)after administration with WFM.(3)CCI mice had a slight decrease in body weight,and there was no significant difference in body weight between the mice.(4)From the 5th day after operation,the MWT and TWL were significantly decreased in the mice,and the most significant decrease was observed on the 7th day.At the 7th day,MWT continues to decline.(P<0.001).Compared with the sham group,the CCI group was significantly lower than that in the CCI group(P<0.001).Compared with the CCI group,the WFM-L group,WFM-H group,GBPT group was significantly lower than that of the sham group(P<0.001)(P<0.05 or P<0.001),MWT and TWL were significantly increased.(5)Immunofluorescence staining showed that the proportion of TRPV1 positive neurons in CCI group was significantly increased(P<0.001)compared with sham group,and the ratio of TRPV1 positive neurons in WFM-H group and GBPT group was significantly decreased than that in CCI group(P<0.05 or P<0.001).(6)The relative quantitative results of TRPV1 gene and protein showed that the expression of TRPV1 in CCI group was significantly increased compared with sham group(P<0.001),while WFM-H group,WFM-L group and GBPT group were significantly decreased compared with CCI group(P<0.01 or P<0.05).(7)Calcium imaging showed that the response size and proportion of DRG neurons response to capsaicine in the CCI group were significantly increased(P<0.001),compared with the sham group,while the WFM-H group,GBPT group were decreased(P<0.05 or P<0.001),WFM-L group also decreased,but there was no significant difference.in the WFM-H group,WFM-L group and GBPT group,The amplitude of DRG neurons response to capsaicine was significantly lower than that in the CCI group(P<0.001).Conclusion:A combined water extract of frankincense and myrrh alleviates neuropathic pain in mice via modulation of TRPV1.