APETx2 regulates intestinal motility and visceral sensitivity in post-infectious irritable bowel syndrome mice through 5-HT signalling pathway

To investigate whether APETx2, a potent and selective inhibitor of ASIC3, regulates intestinal motility and visceral sensitivity in post-infectious irritable bowel syndrome (PI-IBS) mice through the 5-HT signalling pathway.The PI-IBS model was established by Trichinella spiralis infection of NIH mice. APETx2(120 µg/kg) was administrated to PI-IBS mice by intraperitoneal injection once a day, lasting for 7 days. The gastrointestinal function of mice was assessed by the time of the first dark stool and the number of pellets defecated within 2 h. The visceral sensitivity was tested via abdominal withdrawal reflex. The protein levels of 5-HT and CRF in colon tissues were detected by immunohistochemistry. The changes in serum 5-HT and colon CRF contents were detected by ELISA. The mRNA levels of colon 5-HT4R and CRF were detected by RT-qPCR. The protein levels of colon 5-HT4R and dorsal root ganglion (DRG) ASIC3 were detected by Western blotting.The results indicated that APETx2 could markedly improve gastrointestinal function and visceral sensitivity in mice. Moreover, APETx2 could reduce the expression level of ASIC3 protein in the DRG of PI-IBS mice. APETx2 could increase the expression levels of 5-HT in serum and colon, CRF and 5-HT4R in the colon, and 5-HT4R in brain tissue in PI-IBS mice.APETx2 can improve visceral sensitivity and intestinal motility in PI-IBS through 5-HT signalling pathway.