Dynamic expressions of exchange protein directly activated by cyclic adenosine monophosphate in rat model of liver fibrosis / 中华传染病杂志

ABSTRACT

Objective To investigate the dynamic expressions of exchange protein directly activated by cyclic adenosine monophosphate (cAMP) (Epac) in rat model of hepatic fibrosis(HF).Methods Forty-two male SD rats were divided into control group (n = 6) and model group (n = 36)which was divided into six subgroups of day 4, week 1, week 2, week 4,week 6 and week 8 with six rats in each subgroup. The rat model of HF was established by intraperitoneal injection of dimethylnitrosamine (DMN). The pathological changes of liver were observed by Hematoxylin-Eosin and Masson staining. Reverse transcription-polymerase chain reaction (RT-PCR),immunohistochemistry and Western blot were employed to detect the mRNA and protein expressions of Epac1, Epac2 and transforming gronth factor (TGF)β1 during the process of modeling and localization in the liver. The statistical analysis was done using one-factor ANOVA, LSD-t test,Dunnett T3 test and Pearson linear correlation analysis. Results Rat model of liver fibrosis was established successfully. In control group, Epac1 (0. 031 28±0. 008 96) and Epac2 protein (0.034 43±0. 002 45) mainly expressed in the cytoplasm of hepatocytes. In model group, the level of Epac1 decreased at day 4 (0. 023 97±0. 003 81) and week 1 (0. 015 81±0. 002 48) ,then began to increase at week 2 of modeling and peaked at week 6 (0. 039 54±0. 001 43), which had statistical significance compared to the control group (t= 5.47,11.58 and - 6.18, respectively; all P＜0.05). Epac2 protein expression declined after modeling, reached the lowest level at week 4 (0. 011 21 ±0. 001 32), which had statistical significance compared to the control group (t= 24. 50, P＜0. 05). TGFβ1 protein expression increased after modeling and peaked at week 4 (0. 011 30±0.001 03) which had statistical significance (t= -23. 36, P＜0. 05) compared to the control group (0. 002 08 ±0. 000 18). The expressions of Epac1, Epac2 and TGFβ1 mRNA were consistent with the trend of protein levels.Correlation analysis showed that Epac1 protein was positively correlated with the course of HF (r =0. 703, P＜0.01 ), while Epac2 protein was negatively correlated (r = - 0. 409, P＜0.05). Conclusions During the progression of HF, Epac1 expression tends to decrease firstly and increase afterwards,while Epac2 expression declines continually. Epac may be involved in the pathogenesis of HF.