Fig. 3: Oral administration of D-mannose has long-lasting antidepressant actions by activating the ACSS2-TPH2 axis in mice with CRS-induced depressive-like behaviors.

A CRS-induced male mice with depressive-like behaviors for 4 weeks and male mice with or without 10% D-Mannose supplementation (n = 8) and behavioral testing started on Day29 and lasted for 1 week. B Immobility time in the forced swim test and tail suspension test C in individual animals (n = 8). D Sucrose preference in the presence of CRS and D-Mannose in male mice (n = 8). E RT-PCR analysis of ACSS2 and TPH2 expression levels in Hip of male mice (n = 8) exposure to CRS and 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. F Representative immunoblots and quantification of hippocampal ACSS2, TPH2, ACLY protein levels normalized to loading controls (n = 9) from male mice exposure to CRS and D-Mannose. G Analysis of 5-HT content of HIP by ELISA in male mice with CRS and D-Mannose supplementation (n = 8). H Measurement of serotonin (5-HT) in Hip in CRS-induced male mice with depressive-like behaviors with or without D-Mannose supplementation (n = 5–6) by high performance liquid chromatography (HPLC). I Analysis of TRP, 5-hydroxytryptophan (HTP), 5-HT and 5-hydroxindole acetic acid (HIAA) in hippocampus from Control, CRS-Control, D-Mannose and CRS-D-Mannose groups of male mice (n = 5–7). HTP/TRP and HIAA/5-HT ratios were shown to indicate TPH2 and MAO-A enzyme activity. J C57BL/6J male mice were divided into five groups: Control, CRS-Control, D-Mannose, CRS-D-Mannose, and CRS-D-Mannose with PCPA injection groups (n = 7–10). Male mice with 500 mg/kg PCPA or saline for four consecutive days and the behavioral experiments were performed at 2 h after the last injection. K Immobility time in the forced swimming test and tail suspension test (L) in Control, CRS-Control, D-Mannose, CRS-D-Mannose and CRS-D-Mannose with PCPA injection groups (n = 7–10). M Analysis of 5-HT content of HIP by ELISA in male mice from Control, CRS-Control, D-Mannose, CRS-D-Mannose and CRS-D-Mannose with PCPA injection groups (n = 5–10). N C57BL/6J male mice were divided into four groups: Control, CRS-Control, CRS-D-Mannose, CRS-D-Mannose-SiACSS2 groups (n = 8–10). And behavioral testing started on Day29 and lasted for 1 week. O Immobility time in the forced swimming test and tail suspension test (P) in individual animals (n = 8) from Control, CRS-Control, CRS-D-Mannose, CRS-D-Mannose-SiACSS2 groups (n = 8–10). Q Sucrose preference in the presence of CRS and D-Mannose with or without ACSS2 downregulation by small RNA interference in male mice (n = 8–10). R Representative immunoblots and quantification of hippocampal ACSS2 and TPH2 protein levels normalized to loading controls (n = 6) from male mice exposure to CRS and D-Mannose with or without ACSS2 downregulation. S The protein levels of TPH2 in Hip of male mice (n = 5–10) and 5-HT (T) in Hip of male mice (n = 4) from Control, CRS-Control, CRS-D-Mannose, CRS-D-Mannose-SiACSS2 groups by ELISA assay.