Rg1 protected the hippocampus against D-gal induced aging
To determine whether Rg1 could antagonize brain aging caused by D-gal, we used Rg1 and D-gal to intervene.The biological dynamics of aging in mice revealed that as the injection time and cumulative dose of D-gal increased, the hair of the mice in the aging model group became duller, their activity decreased, their eating decreased, their stool did not form, their weight gain was slow, and the typical signs of natural aging were observed,the other three groups exhibited no clear symptoms of aging.The navigation test of Morris water maze (MWM) revealed that the D-gal group exhibited learning deficits compared to Control group and D-gal+Rg1 groups (repeated-measure ANOVA; (F[5, 25] = 2.3, not statistically significant; Fig 5A),in the spatial exploration test (Fig.5 B, C), the D-gal group number of times crossing the original platform position and percentage of time spent in the original platform quadrant were significantly lower than those of the Control and D-gal+Rg1 groups,the swimming speed of D-gal group was slower than that of the Control group and D-gal+Rg1 group,and the swimming distance of D-gal group was longer(Fig.5 D,E) (paired t test, n=12, p<0.05).The Brain Organ Index(Table.2) was lower in the D-gal group, but higher inthe D-gal + Rg1 group.HE staining (Fig.5 K,L) revealed that in comparison to the D-gal+Rg1 group, the D-gal group’s cells were arranged in a disorderly manner, with varying sizes, uneven staining, and apparent neuronal necrosis, indicating enhanced cytoplasmic eosinophilia,the other three groups exhibited no clear symptoms of aging.Nissl staining (Fig.5 M,N) showed that nerve cells and the Nissl body were reduced in the D-gal group, but increased in the D-gal + Rg1 group.Transmission electron microscope (Fig.5 J) showed that the intracellular organelles in the D-gal group were vacuoles, the RER was expanded and vesicles were present, mitochondria were swollen, the edges of heterochromatin were visible, and the perinuclear space increased,the other groups showed no obvious changes.SA-β-gal staining (Fig.5 O,P) showed that the number of blue-stained senescent cells increased in the D-gal group, whereas the number of blue-stained senescent cells reduced in the D-gal + Rg1 group.P53 protein (Fig. 5 F,G) expression increased in the D-gal group but decreased in the D-gal + Rg1 group. ChAT (Fig. 5 H) and AChE (Fig. 5 I) activity were determined, compared with D-gal group, ChAT activity in Control group and D-gal+Rg1 group increased, while AChE activity decreased(paired t test, n=3, p<0.05). Taken together, D-gal can induce brain senescence in mice, while Rg1 can antagonize this brain senescence.