摘要
Objective To explore toxic effect of γ irradiation on circadian rhythms of cAMP and cGMP in signal pathway between the central nuclei and peripheral lymphocyte.Methods 60 Co γ ray of 0.5 Gy and 5.0 Gy was applied to groups of mice at each circadian timepoint of a day. 24 hours after the irradiation, the pineal and suprachiasmatic nuclei (SCN) were removed, and the T lymphocytes in blood were separated by a step centrifugal and nylon filter treatment, for measurements of cAMP and cGMP by using the RIA procedure. The results were expressed as circadian rhythms of the cAMP/cGMP ratio derived from the Cosinor analysis.Results The daily average cAMP/cGMP ratio in cells of SCN, pineal, serum and lymphocyte changed according to the dose of irradiation at which the mice were exposed. The high dose of 5 Gy increased the ratio, and the low dose of 0.5 Gy decreased the ratio. There was a significant difference of cAMP/cGMP levels between the irradiated and the control groups, as well as between CT00∶00 and CT12∶00 of a day. In addition, the peak phases of the cAMP/cGMP ratio at the low dose groups appeared in advance from about 2 to 8 hours, whereas those at the high dose groups were delayed from about 3 to 6 hours in comparison to that of the normal mice.Conclusion Toxic effect of γ irradiation on the cAMP/cGMP circadian rhythm in the central nuclei and peripheral lymphocyte could be characterized by a low dose hormesis.
Objective To explore toxic effect of γ irradiation on circadian rhythms of cAMP and cGMP in signal pathway between the central nuclei and peripheral lymphocyte.Methods 60 Co γ ray of 0.5 Gy and 5.0 Gy was applied to groups of mice at each circadian timepoint of a day. 24 hours after the irradiation, the pineal and suprachiasmatic nuclei (SCN) were removed, and the T lymphocytes in blood were separated by a step centrifugal and nylon filter treatment, for measurements of cAMP and cGMP by using the RIA procedure. The results were expressed as circadian rhythms of the cAMP/cGMP ratio derived from the Cosinor analysis.Results The daily average cAMP/cGMP ratio in cells of SCN, pineal, serum and lymphocyte changed according to the dose of irradiation at which the mice were exposed. The high dose of 5 Gy increased the ratio, and the low dose of 0.5 Gy decreased the ratio. There was a significant difference of cAMP/cGMP levels between the irradiated and the control groups, as well as between CT00∶00 and CT12∶00 of a day. In addition, the peak phases of the cAMP/cGMP ratio at the low dose groups appeared in advance from about 2 to 8 hours, whereas those at the high dose groups were delayed from about 3 to 6 hours in comparison to that of the normal mice.Conclusion Toxic effect of γ irradiation on the cAMP/cGMP circadian rhythm in the central nuclei and peripheral lymphocyte could be characterized by a low dose hormesis.
