To explore the role of vascular endothelial growth factor (VEGF) in emphysema of rat caused by smog exposure.
Thirty-six 12-week male rats were randomly divided into 2 groups: a smog exposure group (S group), and a normal control group (N group). S group rats were randomly subdivided into 3 groups: S(1) group, S(2) group, S(3) group, which were exposed to smog for 2 weeks, 4 weeks, 8 weeks, respectively; N group rats were randomly subdivided into 3 groups: N(1) group, N(2) group, N(3) group, which were raised in normal oxygen condition for 0 week, 4 weeks, 8 weeks, respectively. The expressions of VEGF mRNA and VEGF protein and kinase-insert domain containing receptor (KDR) protein were determined by reverse transcription-polymerase chain reaction (RT-PCR) and modified SABC immunohistochemistry assay separately. The pathological change in smog exposure rat lung was determined by HE staining. MLI and MAN were determined as an index of emphysema. Variance analysis, nonparametric analysis and correlate analysis were conducted in SPSS 10.0.
(1) There were airway inflammation in S group rat lungs, and an early-emphysema-like change in S(3) group rat lungs: MAN in S(3) group was significantly decreased compared with N(3) group, MLI in S(3) group was significantly increased compared with N(3) group (P < 0.05). (2) VEGF189 mRNA in lung and VEGF protein in alveolar and bronchial epithelium of rats in S(1) group were significantly lower than those in N(1) group (P < 0.01); VEGF189 mRNA, VEGF165 mRNA and VEGF121 mRNA of lung tissue and VEGF protein in alveolar and bronchial epithelium of rats in S(2) group were significantly lower than those in N(2) group (P < 0.01), too; VEGF protein in alveolar and bronchial epithelium and KDR expression in pulmonary vascular endothelium of rats in S(3) group was lower than that in N(3) group (P < 0.01, P < 0.01, P < 0.05), but VEGF mRNA have no difference (P > 0.05). (3) VEGF protein expression in alveolar epithelium and bronchial epithelium had a positive correlation with MAN (r = 0.43, r = 0.37, P < 0.05) and an inverse correlation with MLI (r = -0.42, r = -0.37, P < 0.05).
Smog exposure decrease the expression of VEGF and KDR in rat lung. VEGF might involve in the pathology of emphysema caused by smog exposure.