Effects of rosiglitazone on the expression of connective tissue growth factor in the pulmonary arteries of rats suffering from fibrosis in lung / 中国应用生理学杂志

<p><b>OBJECTIVE</b>To explore the effects of rosiglitazone (RSG), an agonist of peroxisome proliferators-activated receptor-gamma (PPAR-gamma), on the up-regulation of connective tissue growth factor (CTGF) and the deposition of type I and type III collagens in the pulmonary arteries of rats suffering from fibrosis in lung.</p><p><b>METHODS</b>Forty-eight male Sprague-Dawley rats were randomly divided into 4 groups: bleomycin (BLM) plus normal saline (NS) group (n=21), BLM plus RSG group (n=9), NS plus NS group (n=9), and NS plus RSG group (n=9). The rats were received single intratracheal instillation of BLM (5 mg/kg bw) or equal volume of NS as control, and received intra-gastric adminnistration of RSG (3 mg/(kg x day), 14 day) or the same volume of NS as vehicle. In vio, the observation was conducted on day 14 after intratracheal instillation. In vitro, the pulmonary arteries of rats on day 14 after BLM were isolated and incubated with DMEM alone or with RSG (37 degrees C, 5% CO2, for 24 h.</p><p><b>RESULTS</b>In vivo, the expression and the content of CTGF, the contents of type I and type III collagens, and the ratio of type I collagen and type III collagen were increased in the pulmonary arteries of BLM-instilled rats, compared with those of NS-instilled rats (All P < 0.05). The above abnormal changes were ameliorated by RSG (All P < 0.05). In vitro, RSG blocked the up-regulation of CTGF (P < 0.05), but not the deposition of type I collagen and type III collagen in the pulmonary arteries isolated from the BLM-instilled rats (P > 0.05).</p><p><b>CONCLUSION</b>The results suggest that RSG directly blocks the up-regulation of CTGF in pulmonary arteries of rats suffering from fibrosis in lung, and this might be one of the mechanisms underling the ameliorated pulmonary arterial remodeling by RSG.</p>

Expression of connective tissue growth factor in pulmonary artery at the early-stage of pulmonary fibrosis / 生理学报

To ascertain whether connective tissue growth factor (CTGF) participates in the remodeling of pulmonary artery at the early-stage of bleomycin (BLM)-induced pulmonary fibrosis, mean pulmonary arterial pressure, the expression of type I and type III collagens, and the expression and location of CTGF in pulmonary artery and arteriole were investigated in the present study. Sprague-Dawley rats received instillation of BLM [5 mg/kg body weight, in 0.5 mL of normal saline (NS)] or instillation of the same amount of NS as control. Mean pulmonary arterial pressure was detected via a catheter in the pulmonary artery. Type I and type III collagens were examined with Sirius red staining under polarized light. CTGF expression was investigated by using immunohistochemistry, and was represented as average optical density and percentage of positive area of CTGF. The mean pulmonary arterial pressure was higher in rats on day 14 after BLM instillation [(19.5+/-2.9) mmHg] than that in the control rats [(14.8+/-1.2) mmHg] (P<0.05). The type I and type III collagens were increased both in pulmonary artery and arteriole of rats on day 14 after BLM instillation, compared with those in the control rats (P<0.05, P<0.01, respectively). The ratio of type I/III collagens in pulmonary artery was also higher in BLM-treated rats than that in the control rats (P<0.05). The values of average optical density of positive CTGF staining were increased both in pulmonary artery (0.37+/-0.02) and arteriole (0.40+/-0.03) of rats on day 14 after BLM instillation, compared with those in the control rats (artery, 0.34+/-0.01; arteriole, 0.29+/-0.01) (both P<0.05). The percentages of positive area of CTGF were higher in pulmonary artery (8.40+/-1.13) and arteriole (12.4+/-2.0) of rats on day 14 after BLM instillation than those in the control rats (artery: 1.42+/-0.63; arteriole: 1.16+/-0.34), respectively (both P<0.05). The increased positive CTGF staining areas were mainly located in the endothelium and smooth muscle layer. It is therefore concluded that CTGF expression increases in the endothelium and smooth muscle layer of pulmonary artery and arterioles during high pulmonary arterial pressure and remodeling of pulmonary artery at the early-stage of BLM-induced pulmonary fibrosis, and that the increased CTGF might be one of the mechanisms of maintenance and development of pulmonary hypertension.