Ghrelin, a brain-gut peptide that induces anxiety and other abnormal emotions, contributes to the effects of insomnia on emotional behavior. In contrast, the traditional Chinese Medicine remedy Wen Dan Tang reduces insomnia-related anxiety, which may perhaps correspond to changes in the brain-gut axis. This suggests a possible relationship between Wen Dan Tang's pharmacological mechanism and the brain-gut axis. Based on this hypothesis, a sleep-deprived rat model was induced and Wen Dan Tang was administered using oral gavage during model establishment. Wen Dan Tang significantly reduced insomnia-related anxiety and prevented Ghrelin level decreases following sleep deprivation, especially in the hypothalamus. Increased expression of Ghrelin receptor mRNA in the hypothalamus was also observed, suggesting that reduced anxiety may be a result of Wen Dan Tang's regulation of Ghrelin-Ghrelin receptors.

Anxiety disorder is a prevalent neuropsychiatric disorder that afflicts 7.3%~28.0% of the world’s population. Bile acids are synthesized by hepatocytes and modulate metabolism via farnesoid X receptor (FXR), G protein-coupled receptor (TGR5), etc. These effects are not limited to the gastrointestinal tract but also extend to tissues and organs such as the brain, where they regulate emotional centers and nerves. A rise in serum bile acid levels can promote the interaction between central FXR and TGR5 across the blood-brain barrier or activate intestinal FXR and TGR5 to release fibroblast growth factor 19 (FGF19) and glucagon-like peptide-1 (GLP-1), respectively, which in turn, transmit signals to the brain via these indirect pathways. This review aimed to summarize advancements in the metabolism of bile acids and the physiological functions of their receptors in various tissues, with a specific focus on their regulatory roles in brain function. The contribution of bile acids to anxiety via sending signals to the brain via direct or indirect pathways was also discussed. Different bile acid ligands trigger distinct bile acid signaling cascades, producing diverse downstream effects, and these pathways may be involved in anxiety regulation. Future investigations from the perspective of bile acids are anticipated to lead to novel mechanistic insights and potential therapeutic targets for anxiety disorders.

Objective: The mechanism of Wendan Decoction (WDD) against Generalized Anxiety Disorder (GAD) was predicted by network pharmacology and validated by in vivo and in vitro experiments. Methods: The targets of WDD for the treatment of GAD were obtained by a search of online databases. Further, PPI network and KEGG enrichment were used to identify the key targets and pathways. Ultimately, these key targets and pathways were validated by in vivo experiments on GAD mice modeled by repeated restraint stress (RRS) and in vitro experiments on inflammatory factor stimulated BV-2 cells. Results: Through searching the databases, the 137 ingredients of WDD that correspond to 938 targets and 4794 targets related to GAD were identified. Among them, 569 overlapping targets were considered as the therapeutic targets of WDD for GAD. PPI analysis showed that the inflammation-related proteins IL-6, TNF, SRC and AKT1 were the key targets, and KEGG enrichment suggested that PI3K/AKT and MAPK signaling pathways were key pathways of WDD in the treatment of GAD. In vivo experiments, RRS mice exhibited abnormality in behavioristics in open field test (OFT) and elevated plus maze (EPM) and increases in serum corticosterone and the percentage of lymphocytes positive for IL-6 in peripheral blood. These abnormal changes can be reversed by WDD and the positive control drug paroxetine. In vitro experiments, WDD can inhibit IL-6 induced activation of PI3K/AKT and MAPK signaling pathways in BV2 cells, and suppress the ensuing release of inflammatory factors TNF-α, IL-1β and PGE₂, and showed a dose-dependent effect. Conclusion: WDD is able to resist GAD by relieving inflammatory response in peripheral and central system.

Wen‐Dan Decoction (WDD), a formula of traditional Chinese medicine, has been clinically used for treating insomnia for approximately 800 years. However, the therapeutic mechanisms of WDD remain unclear. Orexin‐A plays a key role in the sleep‐wake cycle, while leptin function is opposite to orexin‐A. Thus, orexin‐A and leptin may be important factors in sleep disorders. In this study, 48 rats were divided into control, model, WDD‐treated, and diazepam‐treated groups. The model of insomnia was produced by sleep deprivation (SD) for 14 days. The expressions of orexin‐A, leptin, and their receptors in blood serum, prefrontal cortex, and hypothalamus were detected by enzyme‐linked immunosorbent assay, immunohistochemistry, and real time PCR. Open field tests showed that SD increased both crossing movement (Cm) and rearing‐movement (Rm) times. Orexin‐A and leptin levels in blood serum increased after SD but decreased in brain compared to the control group. mRNA expressions of orexin receptor 1 and leptin receptor after SD were decreased in the prefrontal cortex but were increased in hypothalamus. WDD treatment normalized the behavior and upregulated orexin‐A, leptin, orexin receptor 1 and leptin receptor in brain. The findings suggest that WDD treatment may regulate SD‐induced negative emotions by regulating orexin‐A and leptin expression.

Background: The gut-brain axis and gut microbiota have emerged as key players in emotional disorders. Recent studies suggest that alterations in gut microbiota may impact psychiatric symptoms through brain miRNA along the gut-brain axis. However, direct evidence linking gut microbiota to the pathophysiology of generalized anxiety disorder (GAD) via brain miRNA is limited. In this study, we explored the effects of fecal microbiota transplantation (FMT) from GAD donors on gut microbiota and prefrontal cortex miRNA in recipient mice, aiming to understand the relationship between these two factors.Methods: Anxiety scores and gut microbiota composition were assessed in GAD patients, and their fecal samples were utilized for FMT in C57BL/6J mice. Anxiety-like behavior in mice was evaluated using open field and elevated plus maze tests. High-throughput sequencing of gut microbiota 16S rRNA and prefrontal cortex miRNA was performed.Results: The fecal microbiota of GAD patients exhibited a distinct microbial structure compared to the healthy group, characterized by a significant decrease in Verrucomicrobia and Akkermansia, and a significant increase in Actinobacteria and Bacteroides. Subsequent FMT from GAD patients to mice induced anxiety-like behavior in recipients. Detailed analysis of gut microbiota composition revealed lower abundances of Verrucomicrobia, Akkermansia, Bifidobacterium, and Butyricimonas, and higher abundances of Deferribacteres, Allobaculum, Bacteroides, and Clostridium in mice that received FMT from GAD patients. MiRNA analysis identified five key miRNAs affecting GAD pathogenesis, including mmu-miR-10a-5p, mmu-miR-1224-5p, mmu-miR-218-5p, mmu-miR-10b-5p, and mmu-miR-488-3p. Notably, mmu-miR-488-3p showed a strong negative correlation with Verrucomicrobia and Akkermansia.Conclusion: This study demonstrates that anxiety-like behavior induced by human FMT can be transmitted through gut microbiota and is associated with miRNA expression in the prefrontal cortex. It is inferred that the reduction of Akkermansia caused by FMT from GAD patients leads to the upregulation of mmu-miR-488-3p expression, resulting in the downregulation of its downstream target gene Creb1 and interference with its related signaling pathway. These findings highlight the gut microbiota’s crucial role in the GAD pathophysiology.