OBJECTIVEto 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.

METHODSsprague-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.

RESULTSit 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.

CONCLUSIONCTGF 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.