Journal of Radiation Research and Radiation Proces ›› 2014, Vol. 32 ›› Issue (4): 40204-040204.doi: 10.11889/j.1000-3436.2014.rrj.32.040204

• RADIOBIOLOGY AND RADIOMEDICINE • Previous Articles     Next Articles

Effects of low dose rate neutron-gamma ray mixed irradiation on CYP7A1 mRNA expression in rat liver

OUYANG Kehan1  SHEN Xianrong1,2  HE Ying2   

  1. 1(Department of Nuclear Science and Engineering, Naval University of Engineering, Wuhan 430033, China)
    2(The naval Medical Research Institute, Shanghai 200433, China)
  • Received:2014-03-31 Revised:2014-05-03 Online:2014-08-20 Published:2014-06-25

Abstract:

The aim was to analyze the effects of low dose rate neutron-gamma mixed irradiation on the mRNA expression of hepatic cholesterol 7α-hydroxylase (CYP7A1) gene in the rat and its potential mechanism. Sixty rats were randomly divided into 4 groups: irradiated group in which 20 rats were irradiated for 14 d; control group in which 10 rats were sham irradiated for 14 d; irradiated group in which 20 rats were irradiated for 31 d; control group in which 10 rats were sham irradiated for 31 d. The irradiated rats were irradiated with low dose rate 60Co γ-rays at 0.0167 Gy•h−1 for 2 h and 252Cf neutron at 0.028 mGy•h−1 for 20 h. After being irradiated for 14 d and 31 d, 20 irradiated rats and 10 control rats were killed respectively. The total RNA was extracted from livers. The real-time PCR was used to detect the expression level of hepatic CYP7A1 gene and some nuclear receptor genes, such as peroxisome proliferator activated receptor alpha (PPARα), farnesoid X receptor (FXR), pregnane X receptor (PXR), hepatocyte nuclear factor 4 alphas (HNF4?) and liver X receptor alpha (LXR?), which involved in CYP7A1 transcriptional regulation. The results showed that the mRNA level of hepatic CYP7A1 gene in the irradiated rats which were irradiated for 14 d significantly decreased by 44%( p<0.01) of that in the control group rats, the mRNA level of hepatic PXR gene in the irradiated rats which were irradiated for 14 d increased by 1.69-fold of that in the control group rats, while the mRNA levels of PPARα, FXR, HNF4α and LXRα in the irradiated rats which were irradiated for 14 d did not change significantly compared with the control rats; the mRNA level of hepatic CYP7A1 gene in the irradiated rats which were irradiated for 31 d rather significantly decreased by 22%(p<0.01) of that in the control rats, the mRNA level of hepatic PXR gene in the irradiated rats which were irradiated for 31 d significantly increased by 2.34-fold (p<0.01) of that in the control rats, while the mRNA levels of PPARα, FXR, HNF4α and LXRα in the irradiated rats which were irradiated for 31 d didn’t change significantly compared with the control rats. Thus, after exposure to low dose rate neutron-γ rays co-irradiation in a period, the mRNA level of hepatic CYP7A1 gene in the rat significantly decreased with the accumulation of the absorbed dose. The possible mechanism of the change was that the co-irradiation led to the significant increase transcriptional level of PXR gene, but PXR repressed the transcription of CYP7A1 gene.

Key words: Low dose rate, 60Co γ-rays, Neutron, CYP7A1 gene, Rat

CLC Number: 

  • R811.5,TL71