The Study On Rat Splenic Lymphocyte Apoptosis Regulated By NF-?B Through Activating HPA Axis Induced By Aluminum

In this study,eighty 5-week-old healthy male Wistar rats(weighing about 115 g)were divided into four different groups(20 rats per group)at random: control group(CG,0 mg/kg B.W.Al Cl3),low-dose group(LG,64 mg/kg B.W.Al Cl3),mid-dose group(MG,128 mg/kg B.W.Al Cl3),and high-dose group(HG,256 mg/kg B.W.Al Cl3).All the rats were adapted to the new environment for one week before the test,and then were orally fed different doses of Al Cl3·6H2O in drinking water for 120 days,respectively.The contents of corticotropin releasing hormone(CRH),adrenocorticotrophic hormone(ACTH)and glucocorticoids(GCs)in rat serum and the activities of caspase-9 and caspase-3 in rat lymphocytes were detected by ELISA,the apoptosis indexes were detected by FAC scan flow cytometry,the mRNA expressions of GCR?NF-?B?Bcl-2 ? Bax ? caspase-9 and caspase-3 in rat lymphocytes were detected by q RT-PCR,and the nucleus protein expressions of GCR and NF-?B in rat lymphocytes were detected by western blot(WB).The results showed as follows:(1)The rat serum contents of CRH,ACTH and GCs and mRNA,nucleus protein expressions of GCR of splenic lymphocytes in all Al-treated rats were markedly higher than those in CG(p<0.05,p<0.01),which indicated that Al activated the hypothalamus-pituitary-adrenal(HPA)axis.(2)The early and later apoptosis indexes of splenic lymphocytes were significantly higher in the MG and HG(p<0.01)than those in CG.The ratios of Bcl-2/Bax mRNA expressions in all Al-treated lymphocytes were significantly lower than those in CG(p<0.01).The activities and mRNA expressions of caspase 3 and caspase 9 were markedly higher in LG,MG and HG than those in CG(p<0.05,p<0.01).These results indicated that Al induced splenic lymphocyte apoptosis in rats.(3)The mRNA and nuclear protein expressions of NF-?B were significantly lower in all Al-treated splenic lymphocytes of rats than those in CG(p<0.01).The nuclear protein expressions of GCR and NF-?B were negatively correlated in splenic lymphocytes of rats.In addition,the mRNA expressions of NF-?B were positively correlated with those of Bcl-2,but negatively correlated with those of Bax in splenic lymphocytes of rats.These results indicated that NF-?B played a key role in splenic lymphocyte apoptosis induced by Al through HPA axis in rats.The above results showed that Al induced splenic lymphocyte apoptosis regulated by NF-?Bthrough HPA axis in vivo.These results can provide the basic for the research on the immunotoxicity of Al.