Background: Anxiety disorders (ADs) are the most prevalent mental disorders worldwide. Stress-induced activation of the hypothalamic-pituitary-adrenal (HPA) axis and dysbiosis of gut microbiota seem to contribute to the onset of ADs. This study was designed to investigate the ameliorative effect of volatile oil of Zanthoxylum bungeanum (VOZB) on chronic unpredictable stress (CUS) induced anxiety behavior, as well as the altered HPA axis and gut microbiota.
Methods: Experimental rats were exposed to the CUS for 14 consecutive days. Meanwhile, VOZB was administered at doses of 50, 100 and 200 mg/kg/day for 14 days. The anxiety behavior was evaluated by elevated plus-maze (EPM) and open field (OF). The protein expressions and mRNA levels of corticotropin-releasing hormone (CRH) and glucocorticoid receptor (GR) in hypothalamus was determined, as well the hormone levels of HPA axis in serum. Furthermore, gut microbiota was detected by16S rRNA gene sequencing. The chemical constituents of VOZB were identified by GC-MS analysis.
Results: VOZB treatment (100 and 200 mg/kg/day) increased the ratio of open-arm entries and time in EPM test, as well as the central zone entries and time in OF test. Moreover, VOZB treatment reduced the protein expressions and mRNA levels of CRH, but elevated those of GR in hypothalamus. Similarly, the hormone levels of the HPA axis in serum were decreased by VOZB treatment. Besides, VOZB treatment restored the CUS-induced dysbiosis of gut microbiota, raising the Sobs and Chao indexes, inhibiting Lachnospiraceae, but facilitating Bacteroidales_S24-7_group, Lactobacillaceae, and Prevotellaceae. Additionally, Sobs and Chao indexes were negatively correlated to the serum corticosterone and CRH levels.
Conclusion: VOZB showed an ameliorative effect on CUS-induced anxiety behavior, potentially via inhibiting activation of the HPA axis and restoring the dysbiosis of gut microbiota, thus improving the stress-induced abnormality of the microbiota-gut-brain axis.



中文翻译：

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花椒果皮挥发油改善下丘脑-垂体-肾上腺轴和肠道微生物群以减轻大鼠慢性不可预测的应激性焦虑行为

背景：焦虑症（ADs）是世界范围内最普遍的精神障碍。应激诱导的下丘脑-垂体-肾上腺 (HPA) 轴激活和肠道菌群失调似乎是导致 AD 发病的原因。本研究旨在研究花椒挥发油(VOZB) 对慢性不可预知压力 (CUS) 引起的焦虑行为以及 HPA 轴和肠道菌群改变的改善作用。
方法：实验大鼠连续 14 天暴露于 CUS。同时，VOZB 以 50、100 和 200 mg/kg/天的剂量给药 14 天。通过高架十字迷宫（EPM）和开放场（OF）评估焦虑行为。测定下丘脑促肾上腺皮质激素释放激素（CRH）和糖皮质激素受体（GR）的蛋白表达和mRNA水平，以及血清HPA轴激素水平。此外，通过16S rRNA基因测序检测肠道微生物群。通过GC-MS分析鉴定了VOZB的化学成分。
结果：VOZB 治疗（100 和 200 mg/kg/天）增加了 EPM 测试中的开臂进入率和时间，以及 OF 测试中的中心区进入率和时间。此外，VOZB 治疗降低了 CRH 的蛋白质表达和 mRNA 水平，但提高了下丘脑 GR 的水平。同样，VOZB 处理降低了血清中 HPA 轴的激素水平。此外，VOZB 治疗恢复了 CUS 引起的肠道菌群失调，提高了 Sobs 和 Chao 指数，抑制了毛螺菌科，但促进了拟杆菌属_S24-7_组、乳酸杆菌科和普雷沃菌科。此外，Sobs 和 Chao 指数与血清皮质酮和 CRH 水平呈负相关。
结论：VOZB 对 CUS 引起的焦虑行为有改善作用，可能通过抑制 HPA 轴的激活和恢复肠道菌群的生态失调，从而改善应激诱导的菌群-肠-脑轴异常。