Modified Xiaoyaosan Regulates the Neuro-Immune Microenvironment in Chronic Stress: A Preclinical Meta-Analysis and NF-kappaB Pathway Mechanism Exploration

Background: Chronic unpredictable mild stress (CUMS) triggers systemic pathologies, notably depression and endocrine disorders such as hyperprolactinemia (HPRL). Xiaoyaosan (XYS), a classic traditional Chinese medicine formulation, has been proven effective in treating these stress-induced diseases. However, the precise molecular mechanisms linking its systemic endocrine regulation remain unclear. This study aims to evaluate the multi-target mechanisms of XYS through a combined meta-analytical and experimental approach. Methods: First, a meta-analysis of 25 preclinical studies comprising 569 animals evaluated the efficacy and underlying mechanisms of XYS in CUMS-induced models. Concurrently, an in vivo HPRL rat model was innovatively established using CUMS combined with an intraperitoneal injection of metoclopramide to investigate the pharmacological mechanisms of XYS. Hypothalamic tissues and serum were analyzed using ELISA, Western blot, Real-Time PCR, and immunofluorescence. Results: The meta-analysis demonstrated that XYS significantly ameliorates CUMS-induced weight loss, behavioral despair and anhedonia, with therapeutic mechanisms heavily linked to regulating neuroinflammation and the hypothalamic–pituitary–adrenal axis. Corroborating these systemic benefits, our in vivo experiments mechanistically revealed that XYS attenuated the expression of glial response markers, specifically microglia (IBA-1) and astrocytes (GFAP). XYS also downregulated the expression of iNOS, NADPH-Oxidase 2, and Dopamine D2 receptor, while upregulating Cryab closely associated with the NF-κB inflammatory cascade. This modulation coincided with suppressed secretion of pro-inflammatory cytokines, restoring tyrosine hydroxylase (TH) positive expression levels in the hypothalamic dopaminergic microenvironment. Conclusions: XYS functioned as a multi-target systemic regulator by modulating factors associated with the NF-κB/Cryab inflammatory cascade. This synergistic buffering of the neuro-immune microenvironment assisted in maintaining TH expression and restoring systemic equilibrium, providing strong preclinical evidence for XYS as a comprehensive preventive strategy against the onset of stress-induced mood and endocrine disorders.