BACKGROUND: Interstitial collagenase has been considered as an essential enzyme for collagenolysis in liver fibrosis, because type Ⅰand Ⅲ collagens increase predominantly in liver fibrosis. The present study aimed to demonstrate the gene expression of matrix metalloproteinases-13 (MMP-13) in the progressive phases of ethanol induced experimental liver fibrosis in rats.
METHODS: Thirty-four Sprague-Dawley rats were randomly divided into two groups. The experimental group (24 rats) was given ethanol (44%, 7 g/kg) every day and the control group (10) was given normal saline. Liver samples were harvested from experimental rats at 4, 12 and 24 weeks respectively. The kinetics of MMP-13 mRNA expression was assayed by semi-quantity reverse transcriptase polymerase chain reaction (RT-PCR).
RESULTS: In normal rat liver, a faint band for MMP-13 mRNA was observed by RT-PCR (0.24±0.41). The gene expression of MMP-13 was increased in the liver of the rats treated with ethanol for 4 weeks (0.62±0.54), but it was not considered statistically significant (P>0.05). And the livers from 12-week-treated rats showed a marked mRNA expression (1.65±0.47, P<0.01). Once fibrosis became prominent (24 weeks), a faint band of MMP-13 mRNA was observed (0.39±0.25).
CONCLUSION: MMP-13 participates in the degradation of newly-formed matrix in the early phase of rat liver fibrosis induced by ethanol, and it was induced in a distinct time frame.