Surgical intestinal manipulation increases gene expression of TrkA, CGRP, and PAR-2 IN dorsal root ganglia in the rat

Tachykinin antagonists ameliorate surgically induced impairment of gastrointestinal motility in rats

The protective effects of tachykinin receptor antagonists: SR140333 (NK₁ receptor), SR48968 (NK₂ receptor), and SB222200 (NK₃ receptor) were tested in rats against a surgically induced postoperative inhibition of gut motility, a common complication of abdominal surgery. The small intestinal transit of Evans blue was measured 24-h post-surgery in untreated rats and animals subjected to skin incision, laparotomy, or laparotomy followed by gut evisceration and manipulation. Surgical procedures were conducted under diethyl ether anesthesia. In comparison to untreated and ether-anesthetized rats, animals undergoing skin incision, laparotomy, or laparotomy with gut evisceration and manipulation showed a significant decrease in the intestinal transit of Evans blue. The pretreatment with NK₁ (3-100 µg/kg), NK₂ (3-30 µg/kg), and NK₃ (10-300 µg/kg) blockers before surgery ameliorated the inhibitory effects of gut manipulation in a dose-dependent manner. Moreover, the submaximal and maximal doses of NK₃ antagonists showed a trend toward reversing not only the inhibition caused by gut manipulation but also laparotomy. An additive effect of combining submaximal doses of NK_1-3 blockers was observed in animals pretreated with NK₁  + NK₂ compared to single-agent NK₁ and NK₂ . Additionally, doublets: NK₁  + NK₃ or NK₂  + NK₃ and a triplet: NK₁  + NK₂  + NK₃ proved to be more effective than NK₂ antagonist alone. In contrast, NK_1-3 blockers have not markedly affected the intestinal propulsion in untreated rats or animals subjected to skin incision or laparotomy. NK_1-3 blockers ameliorated the suppressed small-bowel gut motility 24 post-surgery. Combined pretreatment with NK_1-3 antagonists provided selective, additive benefits compared to single agents.

Electroacupuncture Relieves Visceral Hypersensitivity by Inactivating Protease-Activated Receptor 2 in a Rat Model of Postinfectious Irritable Bowel Syndrome

Background

The role of protease-activated receptor 2 (PAR2) in the analgesic effect of electroacupuncture (EA) on visceral hypersensitivity (VH) in postinfectious irritable bowel syndrome (PI-IBS) has yet to be elucidated.

Aim

In this study, we investigated the molecular mechanisms underlying the analgesic effect of EA in a rat model of PI-IBS.

Methods

Visceral hypersensitivity was evaluated by the abdominal withdrawal reflex test before and after administration of the PAR2 agonist, PAR2-AP, and/or EA. The protein expression and mRNA levels of PAR2, CGRP, SP, and TPSP in colon tissues were measured by immunofluorescence, western blot, and RT-PCR.

Results

We found that EA could alleviate VH and significantly decrease protein and mRNA levels of PAR2, TPSP, CGRP, and SP in PI-IBS rats. The analgesic effect of EA on VH was slightly reduced in the presence of PAR2-AP.

Conclusions

These results suggest that EA alleviates VH symptoms through downregulation of the levels of the TPSP/PAR2/SP/CGRP signaling axis in colon tissues in PI-IBS rats. Together, our data suggests that PAR2 plays a critical role in the analgesic effect of EA on VH in PI-IBS.