OBJECTIVE To investigate the effect and mechanism of vitamin C on anxiety- and depression-like behaviors induced by chronic restraint stress(CRS) in female mice.

METHODS The antidepressant activity of different doses of vitamin C in normal female mice was screened using the forced swim test to select the optimal dose, which was further applied to CRS-induced anxiety-depression model female mice to evaluate its efficacy. The control mice were fed normally for 2 weeks, while the model mice received CRS treatment daily for 2 weeks. Depressive-like behavior was assessed using the sucrose preference test, and mice exhibiting depressive behavioral phenotypes were further divided into a CRS model group and a CRS+vitamin C group. Behavioral effects on anxiety and depression were observed 24 h after the injection. Whole-genome methylation sequencing, differential methylation analysis and Western blotting were employed to elucidate the mechanism underlying the antidepressant effects of vitamin C.

RESULTS  In normal female mice, 200 mg·kg⁻¹ vitamin C significantly reduced the immobility time in the forced swim test (P<0.01). After CRS treatment, most mice exhibited anxiety- and depression-like behaviors, including significantly reduced time spent and entries into the open arms of the elevated plus maze(P<0.01), reduced time(P<0.05) and distance traveled(P<0.01) in the central area of the open field test, significantly increased immobility time in the tail suspension test and forced swim test(P<0.01), and a decline in sucrose preference rate(P<0.001). Compared with the CRS model group, the CRS+vitamin C group showed an increased sucrose preference rate(P<0.01), reduced immobility time in the tail suspension test and forced swim test(P<0.01), increased time spent(P<0.01) and entries(P<0.05) into the open arms of the elevated plus maze, and increased time spent and distance traveled in the central area of the open field test(P<0.05). Vitamin C reversed the CRS-induced decrease in the expression of brain-derived neurotrophic factor(BDNF) in the medial prefrontal cortex and the downregulation of downstream Akt signaling pathway activity. Whole-genome methylation sequencing revealed that, compared with the CRS model group, the CRS+vitamin C group exhibited 13820 significantly differentially methylated regions and a decrease in the methylation levels of 7,708 genes, including the key downstream signaling molecule of BDNF, ribosomal S6 protein kinase β2, suggesting that vitamin C may facilitate the activation of the BDNF signaling pathway by reducing DNA methylation levels and upregulating the transcriptional activity of related genes.

CONCLUSION Vitamin C reversed CRS-induced anxiety- and depression-like behaviors in female mice, and the mechanism may involve the restoration of BDNF signaling in the medial prefrontal cortex.