[Role of connective tissue growth factor and α-smooth muscle actin in pulmonary fibrosis among acute paraquat poisoned rats].

Objective: to observe the expression of the connective tissue growth (CTGF) and a smooth muscle actin (α-SMA) in acute paraquat (PQ) poisoned rats and investigate the mechanism of paraquat-induced pulmonary fibrosis.

Methods: sprague-Dawley rats were randomly divided into two experimental groups: control group (6 rats) and PQ group (56 rats). On the 3rd, the 7th, the 14th, the 28th and the 56th day after exposure, the expression of CTGF and α-SMA were evaluated by SABC Immunohistochemistry and Western blot; and the relationship of the expression with pathologic score, hydroxyproline were also analyzed, respectively. The lung pathological changes of rats were observed and pathological evaluation was made.

Results: it was similar that the expression pattern of CTGF, α-SMA detected by immunohistochemistry and Western blot. With the time passing, their expression in PQ group increased gradually compared with control group (P < 0.05 or P < 0.01). The increasing extent of CTGF, α-SMA were gentle on the 3rd, the 7th day. While their increasing extent was rapid from the 14th to the 56th day. CTGF was positively correlated with α-SMA, pathologic score and hydroxyproline respectively (r = 0.74, r = 0.87, r = 0.71, P < 0.05 or P < 0.01). Meanwhile, the histological changes such as lung fibroblast proliferation, disorganized collagen fibers were observed in PQ group.

Conclusion: CTGF and α-SMA could play an important role in the development of pulmonary fibrosis caused by paraquat poisoning; CTGF may promote the transformation of fibroblasts to myofibroblasts and further strengthen the ability of synthesis collagen and extracellular matrix.