Fig. 2: Acute D-mannose administration possesses fast-acting antidepressant activity via ACSS2.

A Immunoblot analyses of SH-SY5Y cells expressing ACSS2 with 1 mM D-glucose, 1 mM D-fructose or 1 mM D-Mannose for 24 h with the indicated antibodies were performed. B Analysis of D-Mannose in hippocampus (Hip) in response to chronic restrain stress (CRS) in male mice (n = 8–12). The D-Mannose levels were normalized to those in Control male mice. C 125ul 5 mM FITC-D-Mannose was injected into male mice via tail vein, the intensity and distribution of red fluorescence were detected by the small animal three-dimensional live imaging system at 5 min, 30 min, 60 min, 3 h, 6 h, 9 h, 12 h and 24 h after injection. D 125ul 5 mM FITC-D-Mannose was injected into male mice via tail vein, the intensity and distribution of red fluorescence were detected by the small animal three-dimensional live imaging system at 5 min, 30 min, 60 min, 3 h, 6 h, 9 h, 12 h and 24 h after injection. E 200ul 5 mM FITC-D-Mannose was injected into male mice via gavage, the intensity and distribution of red fluorescence were detected by the small animal three-dimensional live imaging system at 1 h, three h and 24 h after injection. F 200 μl 5 mM FITC-D-Mannose was injected into male mice via gavage, the intensity and distribution of red fluorescence were detected by the small animal three-dimensional live imaging system at 1 h, 3 h and 24 h after injection. G SH-SY5Y cells were incubated with 20 μM FITC labeled D-Mannose and CY5 tagged glucose alone or together followed by flow cytometry analysis. H 400 μl 20% D-Mannose or 400 μl water were injected into male mice via gavage and TST behavior test was detected at 30 min, 1 h, 3 h, 6 h, 9 h, 12 h and 24 h after injection. I Immobility time in the tail suspension test from male mice in individual animals from wild type and D-Mannose supplementation groups (n ≥ 8) at 30 min, 1 h, 3 h, 6 h, 9 h, 12 h and 24 h after intragastric administration of 400 μl water or 20% D-Mannose. J Representative immunoblots and quantification of hippocampal ACSS2, BDNF, P-EF2, EF2, Synapsin a/b, PSD95, and EAAT2 protein levels normalized to loading controls (n = 4) from D-Mannose supplementation male mice. K C57BL/6 J male mice suffered from chronic binding stress for 4 weeks, 400 μl 20% D-Mannose or 400 μl water were injected into male mice via gavage on Day29 and TST behavior test was detected at 3 h, 6 h, 9 h, 12 h and 24 h after injection. L Immobility time in the tail suspension test from male mice in individual animals from wild type, CRS and CRS-D-Mannose groups (n = 10) at 3 h, 6 h, 9 h,12 h and 24 h after intragastric administration of 400 μl water or 20% D-Mannose. M RT-PCR analysis of ACSS2 and TPH2 expression levels in Hip of male mice (n = 8) exposure to Control, CRS and CRS-D-Mannose. Data were normalized with GAPDH mRNA levels and presented as fold changes compared with control group. Scale bars represent mean values and error bars represent SEM. N Representative immunoblots and quantification of hippocampal ACSS2, BDNF, and TPH2 protein levels normalized to loading controls (n = 4) from male mice exposure to CRS and D-Mannose. O Representative photomicrographs of dendritic spines from DG granular cells, scale bar, 10 μm. And Spine density in dendrites of DG granular cells, (Control n = 3, CRS n = 3 and CRS-D-Mannose n = 3 per group). Values are indicated as mean ± SD one-way ANOVA and multiple comparison test, *P ≤ 0.05 **P ≤ 0.01. All the experiments were repeated at least three times independently. P Analysis of 5-HT content of HIP by ELISA in male mice from Control, CRS, and CRS-D-Mannose groups (n = 6–8). Q C57BL/6J male mice were injected with lentivirus of ACSS2 or control group with NC (2 μl was injected into the left and right hippocampus respectively; n = 8–10 mice per group) in stereotactic location in the hippocampus. 400 μl 20% D-Mannose or 400 μl water were injected into male mice via gavage on Day29 and TST behavior test was detected at 3 h after injection. R Immobility time in the tail suspension test from male mice in individual animals from si-NC, si-ACSS2, and si-ACSS2-D-Mannose groups (n = 8–10).