RESUMO
Aim To explore the effect of γ-ray on the mRNA,protein expression levels and metabolic activity level of the key drug metabolic enzyme CYP3A1 in rat liver. Methods Wistar rats were randomly divided into control group, 24 h post-radiation group and 72 h post-radiation group. The experimental group was exposed to total body irradiation of single 6 Gy γ-ray. Blood was collected from the orbital venous plexus for blood routine examination and biochemical analysis 24 h and 72 h after irradiation, and liver tissue was prepared for quantifying expression of CYP3A1 mRNA and liver-specific microRNA (miR-122-5p) through RT-PCR. The expression level of CYP3A1 protein was analyzed by Western blot, and the metabolic activity level of CYP3A1 detected by the specific substrate midazolam combined with LC-MS method. Results Com¬pared with the control group, the weights of the rats in the radiation group significantly decreased, and the number of white blood cells was markedly reduced. Simultaneously, the activities of alanine aminotrans-ferase and alkaline phosphatase continuously descended, as well as the levels of total bilirubin and bile acid significantly increased, which indicated that the liver may be damaged after radiation. The relative expression of CYP3A1 mRNA continued to increase significantly 24 h and 72 h after irradiation. CYP3A1 protein expression and metabolic activity levels showed an obvious increasing trend 24 h after irradiation, and rose significantly 72 h after irradiation compared with the control group. At the same time, the expression of miR-122-5p in liver of rats in the 24 h and 72 h post-radiation group continued to decrease rapidly compared with the control group. Conclusions γ-ray radiation may arouse damage effect on liver, which leads to the continuous up-regulation of the mRNA and protein expression levels of the capital metabolic enzyme CYP3A1 in liver tissue, as well as the elevation of the metabolic activity level. The regulatory mechanism might be related to miR-122-5p.