Effects Of Pelvic Nerve Denervation On Expression Of TRPV1 And 5-HT₄ Receptor In The Colonic Mucosa Of Rats

BackgroundIn recent years,the studies of pelvic nerve injury leading to intestinal dysfunction have aroused people's attention gradually.It is observed that the symptoms of some patients have gradually improved clinically over time,but the mechanism is still unclear.Therefore,it is important to clarify the mechanism of compensatory recovery for future treatment research.After pelvic nerve injury,colorectal function mainly relies on the enteric nervous system to compensate.It has been found that enterochromaffin(EC)cells in the intestine are susceptible to mechanical stimulation in the intestine and release 5-hydroxytryptamine(5-HT)is an important mechanism for ENS to regulate colorectal motility.TRPA1 is an important receptor molecule of intestinal EC cells that activates EC cells to release 5-HT and regulates intestinal motility.Our previous study found that the expression of TRPA1 in distal colonic mucosa of rats after pelvic nerve denervation(PND)was consistent with the trend of intestinal motility recovery,suggesting that TRPA1 may play an important role in the recovery of colonic motility in PND rats.Another receptor molecule TRPV1 on the intestinal mucosa can sense the mechanochemical stimulation and inflammatory pain in the intestine.It's not only co-expression with TRPA1,but also in the function of mutual synergy.TRPV1 has been found to play an important role in the regulation of visceral sensitivity and motor function in the distal colon of mice.Therefore,whether TRPV1 is involved in the adaptive recovery of colon motility after pelvic nerve injury attracts our attention.5-HT,as an important signal molecule in the gastrointestinal tract,play an important role in regulation of sense and motor.It is known that 5-HT4 receptors are widely distributed in the IPANs of ENS terminals.So in PND rats,whether the 5-HT released by EC cells is more bound to the 5-HT4 receptors on IPANs after denervation of exogenous nerve to play the role of compensation,it is not clear.So the 5-HT4 receptor has become one of the key to our study.Objective1.To observe the expression of TRPV1 in the distal colonic mucosa of PND rats,and to verify whether it can play a role after the denervation of pelvic nerve.2.To observe the expression of 5-HT4 receptor in distal colonic mucosa of PND rats and to explore whether it may be a downstream target molecule for ENS to play a compensatory role.Methods72 adult male rats were randomly divided into two groups: PND group and sham operation group.The expression of TRPV1 and 5-HT4 receptor protein was detected by immunohistochemistry and Western blot at 1,3 and 7 day after the operation.The m RNA levels of TRPV1 and 5-HT4 receptor were detected by real-time quantitative PCR(RT-q PCR)in the distal colon mucosa of rats at 1,3,and 7 day after the operation.Results1.TRPV1 expression(1)Immunohistochemistry showed that compared with the sham operation group,the positive expression of TRPV1 in distal colonic mucosa of PND rats was significantly decreased at the first day,and gradually increased at the 3rd and 7th day after operation.(2)The results of Western blot showed that compared with the sham operation group,the expression of TRPV1 protein in distal colonic mucosa of PND rats was significantly down-regulated at the first day after operation,and gradually recovered at the 3rd and 7th day after operation.(3)RT-q PCR results showed that compared with the sham operation group,the m RNA levels of TRPV1 were significantly reduced in the distal colonic mucosa of PND rats at the first day,and gradually improved at the 3rd and 7th day after operation.2.5-HT4 receptor expression(1)Immunohistochemistry showed that compared with the sham operation group,the positive expression of 5-HT4 receptor in distal colonic mucosa of PND rats was significantly decreased at the first day,and gradually increased at the 3rd and 7th day after operation.(2)The results of Western blot showed that compared with the sham operation group,the expression of 5-HT4 receptor protein in distal colonic mucosa of PND rats was significantly down-regulated at the first day after operation,and gradually recovered at the 3rd and 7th day after operation.(3)RT-q PCR results showed that compared with the sham operation group,the m RNA levels of 5-HT4 receptor were significantly reduced in the distal colonic mucosa of PND rats at the first day,and gradually improved at the 3rd and 7th day after operation.Conclusions1.TRPV1 is a receptor molecule on the intestinal mucosa.The trend of its expression is consistent with the recovery trend of colon motility after pelvic nerve injury.This suggests that it is involved in the recovery of colon motility after the pelvic nerve denervation.2.The trend of the expression of 5-HT4 receptor was consistent with the trend of colon dynamic recovery after pelvic nerve injury,indicating that it may be a downstream molecule with the effects of 5-HT and play an important role in regulation of intestinal motility modulated by ENS.