Effect of intraperitoneally injected dexmedetomidine on abdominal adhesions in rats and the role of cholinergic anti-inflammatory pathway

Objective To evaluate the effect of intraperitoneally injected dexmedetomidine on abdominal adhesions in rats and the role of cholinergic anti-inflammatory pathway. Methods Forty clean-grade healthy adult male Sprague-Dawley rats, weighing 220-250 g, were divided into 4 groups (n = 10 each) using a random number table method: sham operation group (Sham group), abdominal adhesion group (AA group), dexmedetomidine group (DEX group) and dexmedetomidine plus methyllycaconitine group (DEX-M group). The rat model of abdominal adhesions was established by cecal friction method.In Sham group, abdominal cavity was only opened and then sutured.Normal saline 2 ml was injected into the abdominal cavity and tail vein in group AA.In DEX and DEX-M groups, normal saline 2 ml and α7 nicotinic acetylcholine receptor antagonist methyllycaconitine 2.4 μg/g (dissolved in 2 ml normal saline) were injected, respectively, and dexmedetomidine 10 μg/kg (dissolved in 2 ml normal saline) was intraperitoneally injected at the same time.The abdominal incision was opened under anesthesia at 7 days after establishing the model to observe the formation of abdominal adhesion, Phillips method was used for scoring, and enzyme-linked immunosorbent assay was used to determine the transforming growth factor-beta1 (TGF-β1) concentrations in ascites and tumor necrosis factor-alpha (TNF-α) concentrations in serum.The rats were then sacrificed, and the caecum tissue and its contralateral peritoneum and adhesion fibrous strips were obtained for examination of the pathological changes with a light microscope. Results Compared with group Sham, the abdominal adhesion score and serum TNF-α concentrations were significantly increased in AA and DEX-M groups, and the TGF-β1 concentration in ascites was significantly increased in AA, DEX and DEX-M groups (P 0.05), and the pathological changes of caecum tissue, contralateral peritoneum and adhesion fibrous strips were accentuated in group DEX. Conclusion Intraperitoneally injected dexmedetomidine can mitigate abdominal adhesions, and the mechanism is related to activating cholinergic anti-inflammatory pathway and reducing systemic inflammatory response in rats. Key words: Dexmedetomidine; Injections, intraperitoneal; Tissue adhesions; Cholinergic anti-inflammatory