Fig. 4
FTY720 pretreatment alleviated lipopolysaccharide (LPS)-induced fear conditioning memory deficit. Mice were intragastrically treated with FTY720 daily for a week followed by i.p. LPS (5 mg kg−1) injection. Behavior tests were conducted and peripheral blood and meninges were collected at 1 day after LPS injection. a, b FTY720 significantly cleared a lymphocytes and b white blood cells in peripheral blood. n = 5 in each group. c The absolute number of CD3+ T cells in the meninges in FTY720-treated mice were dramatically lower than in saline-treated controls. d–f Neither the percentage of d CD3+ T cells in CD45+ cells nor the percentage of e CD4+ T cell or f CD8+ T cells in CD3+ T cells changed after LPS injection in FTY720 pre-treated mice. n = 5 in each group. Data a–f were analyzed by unpaired T test, **P < 0.01, ***P < 0.001. g FTY720 alone did not influence weight changes induced by LPS injection in mice. h FTY720 treatment did not influenced the fear conditioning acquiring, but it greatly reversed the reduced freezing time in the i contextual and j cued fear conditioning test induced by LPS injection. n = 6 in each group. Data g, h, and j were analyzed by two-way ANOVA and followed by Tukey post hoc test and data i was analyzed by one-way ANOVA and followed by Tukey post hoc test, *P < 0.05. Data are presented as mean ± SEM. Con = saline control. i.p. = intraperitoneal