Sevoflurane improves circulatory function and pulmonary fibrosis in rats with pulmonary arterial hypertension through inhibiting NF-κB signaling pathway

X. Zhao, X. Bai, J.-L. Li, S.-M. Li, J. Xi

Department of Cardiovascular Surgery, Qilu Hospital of Shandong University, Jinan, China. xijie@sdu.edu.cn

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• Pharmacology

OBJECTIVE: The aim of this study was to explore the influences of sevoflurane inhalation therapy on circulation function and pulmonary fibrosis in rats with pulmonary arterial hypertension (PAH) and the nuclear factor-κB (NF-κB) signaling pathway.

MATERIALS AND METHODS: A total of 30 adult male Sprague-Dawley rats were randomly divided into three groups, including control group (CTL group, n=10), PAH group (n=10), and PAH + sevoflurane group (n=10) using a random number table. Subsequently, the pulmonary artery right ventricular systolic pressure (RVSP) and right ventricular hypertrophy index (RVHI) were measured. Rats in PAH group were subcutaneously injected with 60 mg/kg monocrotaline once to establish the model of PAH. 28 d later, the differences in the morphology of pulmonary tissues and the protein expression levels of phosphorylated inhibitory κB (p-IκB), p-P65, P65, cyclin D1, proliferating cell nuclear antigen (PCNA) and tubulin among the three groups were analyzed via hematoxylin-eosin (HE) staining and Western blotting, respectively. Meanwhile, the messenger ribonucleic acid (mRNA) expression level of P65 was determined via Reverse Transcription-quantitative Polymerase Chain Reaction (RT-qPCR). Additionally, changes in the expression levels of Ki-67 and α-smooth muscle actin (α-SMA) in rat pulmonary tissues of the three groups were evaluated through immunohistochemistry.

RESULTS: According to HE staining results, compared with CTL group, rats in PAH group exhibited significant thickening of the pulmonary artery wall, reduction of the vascular lumen, inflammatory cell infiltration, and thrombosis in some small arteries. This indicated that the PAH model was successfully established in rats. Compared with PAH group, PAH + sevoflurane group showed a significantly improved morphology of rat pulmonary tissues. Western blotting demonstrated that the protein expression levels of p-IκB, p-P65, and P65 in rat pulmonary tissues of PAH group were remarkably higher than CTL group (p<0.01). However, they were notably down-regulated in PAH + sevoflurane group when compared with those in PAH group (p<0.05). The above experimental results suggested that the NF-κB signaling pathway in pulmonary tissues of rats in PAH group was activated and was inhibited by sevoflurane. Subsequent RT-qPCR results indicated that no significant (N.S.) differences were observed in the mRNA level of P65 among the three groups. Compared with CTL group, PAH group showed significantly up-regulated levels of Ki-67 and α-SMA in rat pulmonary tissues (p<0.01). However, their expression levels were markedly reduced in PAH + sevoflurane group when compared with PAH group (p<0.05). Finally, the detection of pulmonary circulatory function-related indicators illustrated that RVSP and RVHI increased significantly in PAH group in comparison with CTL group. However, they declined remarkably in PAH + sevoflurane group when compared with those in PAH group (p<0.05).

CONCLUSIONS: Sevoflurane down-regulates the levels of p-IκB, p-P65, and P65 to repress the activation of the NF-κB signaling pathway. This may reduce pulmonary fibrosis and ultimately prevent PAH.

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