Effect of interferon-γ on the mRNA expression of TGF- β1 in rectal tissues after introoperative radiotherapy in experimental rabbits

Objective: To study the effect of interferon-γ (IFN-γ) on pathological changes and transforming growth factor-β1 (TGF-β1) changes in rectal tissues of rabbits which received introoperative radiotherapy (IORT). Methods: Fifty-four big female New Zealand albino rabbits were randomly allocated into simple irradiation group, IFN-γ treatment group and blank control group. IFN-γ (2.5×104u/kg·f) was injected into IFN-γ treatment group every four days after IORT for five times. Five rabbits were randomly sacrificed at 4, 8 12, 16 and 20 weeks after IORT except those in blank control group. Pathological changes of the rectum were observed under light microscope and the level of TGF-β1 mRNA expression was observed by hybridization in situ. Results: Light microscopy showed that the pathological changes and the mRNA expression of TGF-β1 in IFN-γ treatment group at different time phases were significantly lower than those in simple irradiation group and blank control group (P<0.05). Conclusion: IFN-γ can significantly inhibit the mRNA expression of TGF-β1, abate acute factitial proctitis and radiation-induced rectal fibrosis.