RESUMO
Aim To iuvestigate the effect and the mechanism of salmonmilt DNA (SMD) on age-related involutions in mouse thymus. MethodsFemale BALB/c of 10 months were divided randomly into three groupsaccording to their weights: high dosage group 333.33 mg/(kg @ d), lowdosage group 166. 67 mg/(kg @ d) and control group 0 mg/(kg @ d) .After five weeks, with Image-Pro Plus (version. 4.0) software, the thymusindexes and the thymoctytes in the thymus section were measured, as wellas the thymus cortex thickness. All the data were analyzed by SAS statisticsoftware. Mieroarray technique was applied to screen the gene fragments,which were differently expressed between the high dosage group and thecontrol group, together with RT-PCR to further confirm some of them.Results No significant differences of the variables including bodyweight, thymus weight and thymus indexes among the three groups werefound (F ＜ 3.0 and P ＞ 0.05, respectively). The thymocytes quanti-ties of thymus cortex and medulla in the high dosage group were significantlyhigher than those of the control group [cortex D(H, C) = 9.46, P ＜ 0.01;medulla t( H.C) = 2.53, P ＜ 0.05]. The thymus cortex thicknesses of bothSMD supplement groups were significantly higher than that of the control group[cortex D(L,C)=3.65, P＞ 0.05; medulla t(L, C)=0.8, P＞ 0.05] .112differently expressed gene fragments were isolated. Furthermore, we foundthe fragments with the logged number of U23789, X80232 and Aw209102were highly expressed in the high dosage group when RT-PCR techniquewas used. Conclusion SMD may reverse the age-related involutions inmouse thymus via up-regulation the expression of proliferation related genesand development and differentiation related genes simultaneously.