〔Abstract〕 Objective To investigate the therapeutic effects and underlying mechanisms of cannabidiol(CBD) and its nano-formulations on depression-like behaviors in mice. Methods A murine model of acute anxiety and depression was established by intraperitoneal administration of lipopolysaccharide(LPS). A total of 55 mice were randomly assigned into several groups: for the long-term study, a control group(Con), a model group(LPS), a cannabidiol group(CBD), a nano-cannabidiol group(NCBD), and a sertraline(SER) group, each consisting of 7 mice. In the short-term study, mice were divided into four groups: the Con group, LPS group, CBD group, and NCBD group, with 5 mice in each group. Except for the Con group and LPS group, which were given distilled water, the remaining groups were administered 25 and 50 mg/kg of cannabidiol and its nano-formulationviaoral gavage. The open field and forced swimming tests were employed to assess anxiety-and depression-like behaviors inmice. Luxol Fast Blue myelin staining was employed to evaluate myelin sheath morphology in the prefrontal cortex, and immunofluorescence staining was utilized to quantify the protein expression levels of silencing information regulator(SIRT2), ionized calcium binding adaptor molecule-1(Iba-1), and interleukin-1β(IL-1β) in the prefrontal cortex. Results In the long-term experiment, the LPS group exhibited a significant reduction in shuttle times(P<0.05), an increase in immobility time(P<0.01), and a decrease in the number and length of myelin sheaths(P<0.05) compared to the Con group. Compared to the LPS group, the depressive behaviors in the CBD, NCBD, and SER groups were significantly alleviated(P<0.01), and the number and length of myelin sheaths increased(P<0.05). In the short-term experiment, compared to the Con group, the LPS group exhibited significantly increased anxiety-and depression-like behaviors(P<0.05), downregulated SIRT2 expression(P<0.01), and upregulated Iba-1 and IL-1β expression(P<0.01). The CBD and NCBD groups demonstrated a reduction in anxiety and depression-like behaviors(P<0.05), an increase in SIRT2 expression(P<0.01), and a decrease in Iba-1 and IL-1β expressions(P<0.05) compared to the LPS group. Conclusion CBD and its nano-formulations effectively mitigate anxiety and depression-like behaviors in mice. The underlying mechanisms may be associated with the reversal of SIRT2 protein expression, demyelination changes, microglial activation, and the levels of inflammatory factors in the prefrontal cortex.