Morinda officinalis oligosaccharides ameliorate corticosterone‑induced depression‑like behaviour in mice by modulating the BDNF signalling pathway and gut microbiota.

The aim of the present study was to elucidate the regulatory effect of Morinda officinalis oligosaccharides (MOOs) on the brain‑derived neurotrophic factor (BDNF)/tropomyosin receptor kinase B (TrkB)/cAMP response element‑binding protein (CREB) signalling pathway and the gut microbiota in a corticosterone (CORT)‑induced chronic stress model. Mice received subcutaneous injections of CORT for 35 days. During this period, different concentrations of MOOs were concurrently administered by gavage. The synergistic regulatory effect of MOOs on the hippocampal BDNF/TrkB/CREB signalling pathway and gut microbiota remodelling was assessed using western blotting, ELISA, 16S ribosomal RNA sequencing, H&E/Nissl staining and reverse transcription‑quantitative PCR in the CORT‑induced chronic stress mouse model. In this model, MOOs alleviated depression‑like behaviour, promoted the expression of BDNF and neuronal nuclear antigen in the hippocampus, normalised monoamine neurotransmitter levels in the brain, activated the BDNF/TrkB/CREB signalling pathway, increased BDNF expression in the hippocampus and remodelled the intestinal microbiota, thereby exerting antidepressant effects. These results suggested that MOOs exerted antidepressant‑like effects in CORT‑exposed mice by attenuating hippocampal neuronal damage, activating the BDNF/TrkB/CREB signalling pathway and ameliorating gut microbiota dysbiosis. These findings provide novel evidence for the clinical application of MOOs in depression.