Effects of Corticosterone,cAMP,cGMP,Ca2+,and Protein Kinase C on Apoptosis of Mouse Thymocytes Induced by X-ray Irradiation

Key words: 
• Corticosterone /
• cAMP /
• cGMP /
• Ca2+ /
• PKC /
• X-ray irradiation /
• Lymphocyte /
• Apoptosis

Abstract: Objective To observe the effects of signal factors of eortieosterone(CS),cAMP,cGMP,Ca2+ and protein kinase C(PKC)on lymphocyte apoptosis in mouse thymus induced by X-rays of 4 Gy in vitro. Methods The DNA lytic rate for thymocytes was measured by fluorospectrophotometry. Results The DNA lytie rate for thymocytes 4-8 hours after irradiation with 2-8Gy was significantly higher than that in the control(P<0.01).As compared with the control,the DNA lytic rate for thymocytes treated with 0.01 umol/L CS(P<0.01),50 ng/mL cAMP(P<0.01),0.05-0.4 ug/mL ionomycin(Iono,P<0.05 or P<0.01)or 0.05-0.4 ng/mL phorbol myristate acetate(PMA,P<0.05 or P<0.01),respectively,was significantly increased,while the rate for thymocytes treated with 50 ng/mL cGMP was not significantly increased.The DNA lyric rate for thymocytes treated with 0.O1umol/L CS(P<0.01),50 ng/mL cAMP(P<0.01),0.2 and 0.4ug/mL Iono(P<0,05),and 0.2 and 0.4 ng/mL PMA(P<0.05)Plus4-Gy irradiation,respectively,was significantly higher than that treated with single 4-Gy irradiation,while the rate for thymocytestreated with 50 ng/mL cGMP plus4-Gy irradiation was not increased.When both 0.4ug/mL Iono and 0.4 ng/mL PMA acted on the thymocytes,the DNA lyric rate for thymocytes was significantly higher than that in the control(P<0.01),the DNA lytic rate for thymocytes treated with both 0.4ug/mL Iono and 0.4 ng/mL PMA plus 4-Gy irradiation was significantly higherthanthattreatedwith single 4-Gy irradiation(P<0.05),but was not significantly bigher than that treated with 0.4ug/mL Iono plus 4-Gy irradiation or 0.4 ng/mL PMA plus 4-Gy irradiation.Conclusion CS,cAMP,Ca2+,and PKC signal factorscall promote thymocyte apoptosis induced by larger dose X-rays.