OBJECTIVETo observe the expression of the matrix metalloproteinase 2 (MMP-2) and membrane-type 1 metalloproteinase (MT1-MMP) in lung of rats exposed to paraquat (PQ) and the effects of Salvia miltiorrhiza monomer IH764-3 on above expression.

METHODSNinety adult healthy Sprague-Dawley (SD) rats were randomly divided into the control group (group A, 6 rats), the exposure group (group B, 42 rats) and the group treated by Salvia miltiorrhiza monomer IH764-3 (group C, 42 rats). The group B and C were treated intragastrically with 1ml of PQ (50 mg/kg), and the group A was treated intragastrically with normal saline. The group C was treated intraperitoneally with 1 ml Salvia miltiorrhiza monomer IH764-3 at the dose of 40 mg/kg a day. The group A and B were treated intraperitoneally with 1 ml normal saline day. The expression of MMP-2 and MT1-MMP was detected on the 1st, 3rd, 7th, 14th, 21st, 28th and 35th days after exposure for all groups.

RESULTSAs compared with the expression level (0.305 ± 0.045) of MMP-2 mRNA in group A, the expression levels of MMP-2 mRNA in Group B significantly increased, which were 0.654 ± 0.077, 0.623 ± 0.051, 0.637 ± 0.024, 0.533 ± 0.043 and 0.552 ± 0.050 on the 1st, 3rd, 7th, 14th, 21st days after exposure, respectively (P < 0.01). As compared with group A, the the expression levels of MMP-2 mRNA on the 1st, 3rd, 7th days in Group C slightly increased, but the expression levels of MMP-2 mRNA on the 1st, 3rd, 7th, 14th, 21st days in Group C were 0.523 ± 0.074, 0.567 ± 0.097, 0.514 ± 0.058, 0.359 ± 0.018 and 0.374 ± 0.020, respectively, which were significantly lower than those in group B (P < 0.01). As compared with the expression level (0.391 ± 0.058) of MT1-MMP mRNA in group A, the expression levels of MT1-MMP mRNA in Group B significantly increased, which were 0.796 ± 0.021, 0.762 ± 0.043, 0.590 ± 0.010, 0.803 ± 0.076 and 0.680 ± 0.034 on the 1st, 3rd, 7th, 14th and 21st days after exposure, respectively (P < 0.01). As compared with group A, the expression levels of MT1-MMP mRNA in Group C significantly increased, which were 0.594 ± 0.010, 0.653 ± 0.044 and 0.564 ± 0.009 on the 1st, 3rd and 21st days after exposure, respectively (P < 0.01). The expression levels of MT1-MMP mRNA in Group C were significantly lower than those in group B (P < 0.05 or P < 0.01).

CONCLUSIONThe expression changes of MMP-2 and MT1-MMP genes of lungs in rats intragastrically exposed to PQ could result in the unbalance the synthesis and degradation of ECM, which may be a cause of lung fibrosis. The Salvia miltiorrhiza monomer IH764-3 could affect the expression of MMP-2 and MT1-MMP genes to a certain extent, resulting in the reduction of lung fibrosis.