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.

Tachykinin Antagonists Reverse Ischemia/Reperfusion Gastrointestinal Motility Impairment in Rats

BACKGROUND

Supraceliac aortic clamping and unclamping produces ischemia-reperfusion (I/R) injury of the splanchnic organs. The protective effects of tachykinin receptor antagonists, SR140333 (NK₁ receptor), SR48968 (NK₂ receptor), and SB222200 (NK₃ receptor), against I/R-induced inhibition of intestinal motility were tested in rats.

MATERIAL AND METHODS

The intestinal transit of Evans blue was measured in untreated rats and animals subjected to skin incision, I/R (1 h superior mesenteric artery occlusion followed by 24 h reperfusion) or sham operation. Surgical procedures were conducted under diethyl ether anesthesia.

RESULTS

The gastrointestinal transit has not been markedly affected in rats, which were anesthetized or subjected to skin incision in comparison with untreated animals. In contrast, a sham operation and I/R have significantly reduced the intestinal motility. Pretreatment with NK_1-3 blockers (SR140333 [3-30 μg/kg]; SR48968 [3-100 μg/kg]; and SB222200 [10-100 μg/kg]) reversed dose dependently the effects of I/R to the level observed after sham operation only. A combination of NK₁+NK₂+NK₃ inhibitors exerted an additive effect compared with NK₁ and NK₂ antagonists used as single agents. Similarly, combined NK₁+NK₂ were more effective than NK₂ alone. Sham operation and I/R have shifted the in vitro carbachol concentration-response curves to the right in comparison with untreated animals, a phenomenon partially reversed by NK₁-NK₃ pretreatment.

CONCLUSIONS

Single-agent and combined treatment with NK_1-3 antagonists markedly attenuated the gastrointestinal dysmotility evoked by I/R injury. The pretreatment with NK₃ blocker proved to be the most active in this experimental setting.

The protective effect of endothelin receptor antagonists against surgically induced impairment of gastrointestinal motility in rats

Endothelin (ET) receptor antagonists: BQ-123 (ET_A), BQ-788 (ET_B), tezosentan (dual ET receptor antagonist) protect against the development of postoperative ileus (POI) evoked by ischemia-reperfusion (I/R). The current experiments explored whether ET antagonists prevent the occurrence of POI evoked by surgical gut manipulation. Intestinal transit was assessed by measuring the rate of dye migration subsequent to skin incision (SI), laparotomy (L), or laparotomy and surgical gut handling (L+M) in diethyl ether anaesthesized rats (E). Experimental animals were randomly sub-divided into two groups depending on the time of recovery following surgery: viz. either 2 or 24 h (early or late phase POI). E and SI did not affect the gastrointestinal (GI) transit. In contrast, L and L+M significantly reduced GI motility in comparison to untreated group (UN). Tezosentan (10 mg/kg), BQ-123 and BQ-788 (1 mg/kg) protected against development of L+M evoked inhibition of intestinal motility in the course of late phase, but not early phase POI. Furthermore, tezosentan alleviated the decrease in the contractile response of the longitudinal jejunal smooth muscle strips to carbachol in vitro induced by L+M. The serum ET(1–21) concentration was not increased in either the early or the late phase POI groups after surgery compared to control animals. This study indicates that delay in the intestinal transit in late phase of surgically induced POI involves an ET-dependent mechanism.