OBJECTIVETo study the effects of nucleotides on apoptosis of thymocytes in mice.

METHODSApoptosis model in vivo was first established and 25 KM mice, 4 weeks old, were randomly divided into 5 groups. One group was control, and the others were test groups. Mice in test groups were injected with DEX (25 mg/kg) and the controls were treated with normal saline. 4, 8, 16, and 24 hours later the thymus and spleen were weighed and lymphocytes in thymus were separated. The apoptosis of lymphocytes was analyzed by using DNA electrophoresis and flow cytometry. 16 hours later lymphocytes apoptosis reached a peak and lasted 24 hours. Methods used to establish apoptosis model in vivo were: mice (4 weeks old) were injected with DEX (25 mg/kg), and thymus lymphocytes were separated 16 hours later and analyzed. The effects of nucleotides on apoptosis of mice thymocytes were investigated in experiment 2. Sixty KM mice, 20 g +/- 2g, 4 weeks old, were divided into four treatments: negative control group (NC), positive control group (PC), nucleotides-additive group 1 (NTS1) and nucleotides-additive group 2 (NTS2).

RESULTSBody weight gained in NST1 and NST2 were 3.71 g, 4.01 g respectively, significantly higher than NC (2.74 g) (P < 0.01) and in NST2 was significantly higher than in PC (2.96 g) (P < 0.01). Thymus index and spleen index were decreased significantly (P < 0.01), and no difference was found with the supplementation of nucleotides (P > 0.05). [Ca2+]i increased to 167.37 nmol/L, 191.16 nmol/L, 180.78 nmol/L in PC, NST1 and NST2 with DEX, being significantly higher than in NC (103.76 nmol/L) (P < 0.01). The percent of apoptosised thymocytes in groups were 0.31%, 11.93%, 9.82%, 11.15%, respectively. Thymus index and spleen index, cell apoptosis and [Ca2+]i were not differed significantly among PC, NTS1 and NTS2 groups.

CONCLUSIONNucleotides should have no significant effects on apoptosis of thymocytes in mice in vivo.