Effects of corticosterone, cAMP, cGMP, Ca2+, and protein kinase C on apoptosis of mouse thymocytes induced by X-ray irradiation.
OBJECTIVE
To observe the effects of signal factors of corticosterone (CS), cAMP, cGMP, Ca2+ andprotein 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 lyric rate for thymocytes 4-8 hours after irradiation with 2-8 Gy 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 micromol/L CS (P<0.01), 50 ng/mL cAMP (P<0.01), 0.05-0.4 microg/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 lytic rate for thymocytes treated with 0.01 micromol/L CS (P<0.01), 50 ng/mL cAMP (P<0.01), 0.2 and 0.4 microg/mL Iono (P<0.05), and 0.2 and 0.4 ng/mL PMA (P<0.05) plus 4-Gy irradiation, respectively, was significantly higher than that treated with single 4-Gy irradiation, while the rate for thymocytes treated with 50 ng/mL cGMP plus 4-Gy irradiation was not increased. When both 0.4 microg/mL Iono and 0.4 ng/mL PMA acted on the thymocytes, the DNA lytic rate for thymocytes was significantly higher than that in the control (P<0.01), the DNA lytic rate for thymocytes treated with both 0.4 microg/mL Iono and 0.4 ng/mL PMA plus 4-Gy irradiation was significantly higher than that treated with single 4-Gy irradiation (P<0.05), but was not significantly higher than that treated with 0.4 microg/mL Iono plus 4-Gy irradiation or 0.4 ng/mL PMA plus 4-Gy irradiation.


CONCLUSIONS
CS, cAMP, Ca2+, and PKC signal factors can promote thymocyte apoptosis induced by larger dose X-rays.
Key Laboralory of Radiobiology Unit, Ministry of Health, School of Public Health, Jilin University, Changchun 130021, Jilin, China.
Shou-Liang
SL
Gong
Li-Hua
LH
Dong
Guang-Wei
GW
Liu
Ping-Sheng
PS
Gong
Wen-Tian
WT
Lu
Hong-Guang
HG
Zhao
Xiao-Jing
XJ
Jia
Yong
Y
Zhao
D000818:Animals; D017209:Apoptosis / Q000187:drug effects* / Q000528:radiation effects; D002118:Calcium / Q000494:pharmacology*; D003345:Corticosterone / Q000494:pharmacology*; D000242:Cyclic AMP / Q000494:pharmacology*; D006152:Cyclic GMP / Q000494:pharmacology*; D015759:Ionomycin / Q000494:pharmacology; D008297:Male; D051379:Mice; D011493:Protein Kinase C / Q000378:metabolism*; D013050:Spectrometry, Fluorescence; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D013950:Thymus Gland / Q000166:cytology / Q000187:drug effects*; D014965:X-Rays
D015759:Ionomycin; D000242:Cyclic AMP; D011493:Protein Kinase C; D006152:Cyclic GMP; D013755:Tetradecanoylphorbol Acetate; D002118:Calcium; D003345:Corticosterone