Effects of penehyclidine hydrochloride pretreatment on expression of nitric oxide synthase and cell apoptosis in rats with endotoxin-induced acute lung injury

Abstract

Objective To evaluate the effects of penehyclidine hydrochloride pretreatment on the expression of nitric oxide synthase (NOS) and cell apoptosis in lung tissues in rats with endotoxin-induced acute lung injury (ALI).Methods Forty adult male Sprague-Dawley rats,weighing 220-270 g,were randomly divided into 5 groups (n =8 each) using a random number table:control group (group C),endotoxin-induced ALI group (ALI group),and penehyclidine hydrochloride 0.03,0.10,0.30 mg/kg groups (Pi-3 groups).ALI was induced with lipopolysaccharide (LPS) 5 mg/kg which was injected via the caudal vein.In P1-3 groups,penehyclidine hydmchloride 0.03,0.10 and 0.30 mg/kg were injected intraperitoneally,respectively,at 1 h before LPS injection,while the equal volume of normal saline was administered in C and ALI groups.The animals were sacrificed at 4 h after ALI models were successfully established and pulmonary specimens were obtained for determination of the cell apoptosis (by TUNEL),expression of NOS mRNA (using PT-PCR),and Bcl-2 and Bax protein (by Western blot),NOS activity (using chemical colorimetry) and NO content (by using nitrate reductase method) and for examination of pathological changes (by light and electron microscopes).Apoptotic index (AI) and the ratio of Bcl-2/Bax was calculated.Results Compared with group C,NOS mRNA and Bax protein expression was significantly up-regulated,NOS activity,NO content and AI were increased,Bcl-2 protein expression was down-regulated,the ratio of Bcl-2/Bax was decreased (P ＜ 0.01),and the degree of pathological changes of the lung was aggravated in ALI and P1-3 groups.Compared with ALI and P1 groups,NOS mRNA and Bax protein expression was significantly down-regulated,NOS activity,content of NO and AI were decreased,Bcl-2 protein expression was up-regulated,the ratio of Bcl-2/Bax was increased (P ＜ 0.01),and the degree of pathological changes of the lung was alleviated in P2-3 groups.There was no significant difference in the indexes mentioned above and results of pathological changes of the lung between group ALI and group P1,and between group P2 and group P3 (P ＞ 0.05).Conclusion Penehyclidine hydrochloride pretreatment ameliorates endotoxin-induced ALI by inhibiting NOS expression and cell apoptosis in rat lung tissues. Key words: Cholinergic antagonists; Endotoxemia; Respiratory distress syndrome, adult; Nitric oxide synthase ; Apoptosis