Camp/Pka Signaling Pathway In-Duces Apoptosis In Al-Treated Lymphocytesin Vitro

Spleen lymphocytes were cultured in vitro to investigate the mechanism of apoptosis signal-ing pathway of cAMP/PKA activated by aluminum from rats. The lymphocytes were isolated from spleen of healthy SD rats and were cultured in1640medium containing calf serum. AIC13·6H2O were added to the supernatants of cultured lymphocytes in final concentration of0mmol·L-1(con-trol group, CG),0.27mmol·L-1(low-dose group, LG),0.54mmol·L-1(middle-dose group, MG), and1.08mmol·L-1(high-dose group, HG), respectively. The morphology of lymphocytes, apopto-sis index, the content of intracellular cyclic adenosine monophosphate (cAMP), the mRNA expres-sion of protein kinase A (PKA), survivin, B cell lymphoma/lewkmia-2(Bcl-2) and Bcl-2asso-ciated X protein (Bax), the mRNA expression of nuclear factor-k-gene binding (NF-κB, p65) and protein expession of nuclear NF-κB (p65) were detected by the method of AO/EB staining, ELISA, flow cytometry, real-time fluorescence quantitative PCR, reverse transportation PCR and western blot, respectively. The results showed as follows:1The apoptotic lymphocytes and Necrotic lymphocytes in Al-treated groups were signifi-cantly higher than those in CG. The apoptosis index of lymphocytes in AlCl3-treated groups was significantly higher than those in CG, and showed dose-effect relationships. It suggusted that alu-minum could induced spleen lymphocytes apoptosis in rats.2The cAMP content and PKA mRNA expression in all AlCl3-treated groups increased signifi-cantly. NF-κB mRNA expression and nuclear protein expression in AlCl3-treated groups decreased significantly. It indicated that cAMP/PKA signaling pathway induced apoptosis by inhibited NF-κB in AlCl3-treated lymphocytes.3The Bax/Bcl-2and survivin mRNA expressions in AlCl3-treated groups decreased significantly. It indicated that the inhibited NF-κB regulated the transcription of apoptotic target genes induced apoptosis in lymphoctyes from rats.The above results showed that AlC13can activate cAMP/PKA signaling pathway, then inhibited NF-κB to decrease the expressions of target gene Bcl-2/Bax and survivin, eventually induced lympho-cytes apoptosis from rats.