Objective : To investigate the antidepressant effects and the underlying mechanisms of tetrahydrocurcumin(THC) and its nanoparticle formulation(THCN). Methods : Forty-six male ICR mice were randomly divided into Con group, LPS group, THC group, THCN group and SER group. A mouse depression model was established by intraperitoneal administration of LPS. The anxiety and depression-like behaviors of mice were evaluated by open field test(OFT) and forced swimming test(FST). Myelin staining was applied to assess the extent of demyelination in the prefrontal cortex of the mice. The prefrontal cortex and hippocampus were further examined for the expression levels of glial fibrillary acidic protein(GFAP) and Toll-like receptor 4(TLR4) through quantitative immunofluorescence assays. Results : Compared with the Con group, the LPS group showed increased anxiety-like and depressive-like behaviors in both the long-term and short-term experiments(P<0.05); the degree of demyelination increased in the LPS group of the long-term experiment(P<0.01); the expression of GFAP was reduced in the LPS group of the short-term experiment(P<0.01), while the expression of TLR4 increased(P<0.05); the expression of TLR4 decreased in the THC group(P<0.01); the expression of GFAP in the prefrontal cortex of the THCN group was reduced(P<0.01), while the expression of TLR4 increased(P<0.05). Compared with the LPS group, the THC group showed reduced depressive-like behaviors in the long-term experiment(P<0.05), while the anxiety-like and depressive-like behaviors of the THCN group and the SER group were reduced(P<0.05), and the anxiety-like and depressive-like behaviors of the THC group and the THCN group were reduced in the short-term experiment(P<0.05); the degree of demyelination was reduced in the THC group, THCN group and SER group in the long-term experiment(P<0.05); the expression of GFAP increased in the THC group of the short-term experiment(P<0.05), while the expression of TLR4 was reduced(P<0.05), and the expression of GFAP increased in the THCN group(P<0.05). Compared with the THC group, the THCN group and the SER group showed reduced anxiety-like behaviors in the long-term experiment(P<0.05); the expression of GFAP in the prefrontal cortex of the THCN group was reduced in the short-term experiment(P<0.05), while the expression of TLR4 in the hippocampal DG area increased in the short-term experiment(P<0.01). Conclusion Tetrahydrocurcumin and its nanoparticle formulation both exert significant ameliorative effects on depression-like behaviors and demyelination in mice induced by lipopolysaccharide. The antidepressant mechanism of THC appears to be mediated through the down-regulation of TLR4 and the up-regulation of GFAP. The mechanism underlying the antidepressant action of THCN seems predominantly focused on the enhancement of GFAP expression.

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.

Objective: To study the rapid antidepressant effects of cannabioiol(CBD) on depression-like mice and its possible mechanism. Methods: Chronic restraint was used to establish a mouse depression model. The test mice were divided into 5 groups: normal control group, model group, positive control group, CBD low-dose group (25 mg/kg) and CBD high-dose group(50 mg/kg). The mice in each group were given intragastric administration one hour before the behavioral experiment. After the behavioral experiment, the hippocampus and prefrontal cortex specimens were collected, and brain-derived neurotrophic factor(BDNF), postsynaptic density protein 95(PSD-95), synaptophysin(SYP) and target of rapamycin(mTOR) were tested by ELISA. Results: Compared with the model group, the central area activity distance percentage, the central area activity time percentage and total distance increased in the open field experiment in the CBD low-dose group. Compared with the model group, the percentage of immobility in the forced swimming experiment in the low-dose CBD group decreased. The ELISA test results showed that CBD could rapidly increase the concentration of BDNF and PSD-95 in the prefrontal cortex, as well as the concentration of SYP and mTOR in the hippocampus and prefrontal cortex. Conclusion CBD can rapidly improve the behavioral performance of depression-like mice, and rapidly up-regulate the level of BDNF and synaptic protein in the hippocampus or prefrontal cortex.