The influence of long-term low-protein intake on nonspecific inflammatory responses and spleen T lymphocytes in middle-aged and older mice / 中华老年医学杂志

ABSTRACT

Objective To explore the effects of long-term low-protein intake on nonspecific inflammatory responses in the liver and T lymphocytes in the spleen in middle-aged and older mice and underlying mechanisms.Methods Fourteen month-old female KM(Kunming)mice were randomly divided into the control group,the low-protein group,the high-protein group and the high-protein + rapamycin group.Additionally,Two month-old female KM mice served as the adult group and were fed regular chow.Animals in the high-protein + rapamycin group received injections of rapamycin intraperitoneally once every two days.Animals were sacrificed at the end of 3 months.Liver histology slices were prepared for the examination of pathological changes and detection of the expression of CD68 and mTOR(the mechanistic target of rapamycin).Spleen lymphocyte suspensions were prepared to count the percentages of CD4+ T and CD8+ T cells.Results Compared with the control group,the low-protein group and the high-protein-+-rapamycin group in histology slides showed regularly arranged hepatocytes,no obvious sinus hepaticus expansion and only mild time-related changes.Moreover,compared with the control group,the low-protein and high-protein + rapamycin groups were associated with increased percentages of CD4+T and CD8 + T cells in the spleen(all P＜ 0.05)and decreased expression of CD68 in the liver(P＜0.05),though the levels of mTOR were similar among the groups.Conclusions Long-term low-protein intake has beneficial effects in mitigating the reduction of T lymphocytes in the spleen and slowing age-related structural and nonspecific inflammatory changes in the liver,possibly through downregulation of the expression of the mTOR protein.