甘草预防气管插管致呼吸道损伤的有效部位筛选

Background??Postoperative sore throat POST is one of the common mild but unpleasant postoperative complications after general anaesthesia. There is evidence that Glycyrrhiza Radix can effectively reduce the incidence of POSTbut its effective fraction remains unclear. Objective??To screen the effective fraction of Glycyrrhiza Radix on preventing respiratory tract injury induced by endotracheal intubation. Methods From April 2021 to July 202260 SPF-grade Wistar rats were randomized into the control groupendotracheal intubation grouplidocaine grouptotal polysaccharides grouptotal saponins grouptotal flavonoids group based on random number table methodwith 10 rats in each group. The endotracheal intubation model was prepared for all groups except the control group. Before intubationeach treatment group was sprayed with a solution consisting of 1% lidocainetotal polysaccharidestotal saponinsand total flavonoids at 1 mL/100 gby body weightto permeate the uvula and peri-soft palate tissue of ratsrespectively. The control and endotracheal intubation groups were sprayed with an equal volume of 0.9% saline. After 2 hours of mechanical ventilationthe endotracheal tube was removedand the pharyngeal mucosa tissues and blood samples of rats were collected under deep anesthesia. Pathological changes of rat pharyngeal mucosa and the expression levels of Toll-like receptor 2 TLR2 and Toll-like receptor 4 TLR4 were observed by hematoxylin-eosin staining HE staining and immunohistochemistry IHC; the expression levels of inflammatory cytokines including serum tumor necrosis factor-α TNF-αinterleukin-2IL-2interleukin-4IL-4interleukin-10IL-10superoxide dismutaseSODmalondialdehydeMDAtotal antioxidant capacityT-AOCand stress hormones including cortisolCorepinephrine Eand norepinephrineNE were measured by enzyme-linked immunosorbent assay ELISA. Results ?HE staining showed mucosal shedding and severe damage of submucosal structure accompanied by a large number of inflammatory cells infiltrated in the endotracheal intubation group; while milder damage of mucosal structure and less inflammatory cells were significantly reduced in the total saponins group. ELISA results showed that compared with the control groupthe levels of TNF-α and IL-2 in the serum of rats increased significantlyand the levels of IL-4 and IL-10 decreased significantly in the endotracheal intubation group P<0.05; compared with the endotracheal intubation groupthe serum levels of TNF-α and IL-2 decreasedand the levels of IL-4 and IL-10 increased in the total saponins groupP<0.05. Compared with the control groupthe MDA level in the serum of rats was significantly increasedand the SOD and T-AOC levels were significantly decreased in the endotracheal intubation groupP<0.05; compared with the endotracheal intubation groupthe MDA level decreased and the levels of SOD and T-AOC increased in the total saponins and flavonoids groupsP<0.05. Compared with the control groupserum CorEand NE levels significantly increased in the endotracheal intubation group P<0.05; compared with the tracheal intubation groupserum CorE and NE levels were decreased in the total saponins group rats P<0.05. The IHC results showed that the average optical density AOD expressed by TLR2 and TLR4 in the endotracheal intubation group was higher than the control groupP<0.05. The AOD expressed by TLR4 in the pharyngeal mucosal tissue of rats in the total saponins group was significantly lower than that of the endotracheal intubation groupP<0.05. Conclusion ?Total saponin is the main effective fraction of Glycyrrhiza Radix for the prevention of respiratory tract injury caused by endotracheal intubation under general anesthesia.