Background Depression is characterized by significant and low mood. Classical antidepressants are still not adequate in treating depression because of undesirable side effects. Folic acid, a member of the vitamin B complex, in considered to be strongly associated with the function and development of the central nervous system. Thus, in this study, we established a model of depression through chronic unpredictable mild stress (CUMS) in rats and assessed the antidepressant effects and mechanisms of folic acid. Methods Sprague–Dawley rats were randomly divided into four groups: control, chronic unpredictable mild stress (CUMS), CUMS treated with folic acid, and CUMS treated with citalopram. Rats were assessed in terms of weight change, open-field test and sucrose preference. Homocysteine, monoamine neurotransmitters, interleukin-6, brain-derived neurotrophic factor (BDNF), β-endorphin levels in the serum and brains of rats were analysed. Results Folic acid exhibited antidepressant-like effects in open-field and sucrose preference tests. Folic acid treatment effectively increased the levels of monoamine neurotransmitters, BDNF and β-endorphin, interleukin-6 and homocysteine levels were also significantly suppressed by folic acid administration. Conclusions These findings serve as preclinical evidence that folic acid plays an antidepressant-like role in several pathways involving monoamine neurotransmitters. Thus, folic acid may be used as a potential antidepressant.

中文翻译：

---

叶酸改善慢性不可预测的轻度应激大鼠模型中的抑郁样行为

背景抑郁症的特点是情绪低落。由于不良副作用，经典抗抑郁药仍不足以治疗抑郁症。叶酸是维生素 B 复合物中的一种，被认为与中枢神经系统的功能和发育密切相关。因此，在本研究中，我们通过大鼠慢性不可预测轻度应激（CUMS）建立了抑郁模型，并评估了叶酸的抗抑郁作用和机制。方法 Sprague-Dawley 大鼠随机分为四组：对照组、慢性不可预测轻度应激（CUMS）组、叶酸治疗组和西酞普兰治疗组。根据体重变化、旷场试验和蔗糖偏好对大鼠进行评估。同型半胱氨酸、单胺类神经递质、白细胞介素 6、分析了大鼠血清和大脑中的脑源性神经营养因子（BDNF）、β-内啡肽水平。结果 叶酸在露天试验和蔗糖偏好试验中表现出类似抗抑郁药的作用。叶酸治疗有效地增加了单胺类神经递质的水平，BDNF 和 β-内啡肽、白细胞介素 6 和同型半胱氨酸水平也受到叶酸给药的显着抑制。结论 这些发现作为临床前证据表明叶酸在涉及单胺类神经递质的几种途径中发挥抗抑郁作用。因此，叶酸可用作潜在的抗抑郁药。叶酸治疗有效地增加了单胺类神经递质的水平，BDNF 和 β-内啡肽、白细胞介素 6 和同型半胱氨酸水平也受到叶酸给药的显着抑制。结论 这些发现作为临床前证据表明叶酸在涉及单胺类神经递质的几种途径中发挥抗抑郁作用。因此，叶酸可用作潜在的抗抑郁药。叶酸治疗有效地增加了单胺类神经递质的水平，BDNF 和 β-内啡肽、白细胞介素 6 和同型半胱氨酸水平也受到叶酸给药的显着抑制。结论 这些发现作为临床前证据表明叶酸在涉及单胺类神经递质的几种途径中发挥抗抑郁作用。因此，叶酸可用作潜在的抗抑郁药。