Youjun Yang

Background: XiaoYao San (XYS), a classical Traditional Chinese Medicine (TCM), has demonstrated efficacy in alleviating stress-related neuropsychiatric disorders. However, its therapeutic potential against maternal immune activation (MIA)-induced neurobehavioral impairments remains unexplored. This study aims to investigate the neuroprotective effects of XYS on MIA-related behavioral dysfunctions and elucidate its underlying mechanisms.Results: Using a poly (I:C)-induced MIA mouse model, we demonstrated that XYS effectively ameliorates autism spectrum disorder (ASD) related behavioral phenotypes. Mechanistic investigations revealed that XYS exerts its therapeutic effects through: (1) Attenuation of core behavioral deficits including enhanced social interaction and reduced repetitive behaviors; (2) Downregulation of intestinal amino acid transporters; (3) Restoration of cerebral glutamate-GABA balance via modulation of glutamine pathway; (4) Structural remodeling of gut microbiota with specific enrichment of Bacteroides spp. Notably, B. uniformis was identified as a key microbial mediator capable of recapitulating XYS-mediated neurophysiological improvements through metabolic regulation.Conclusion: This study elucidates XYS as a multi-target therapeutic agent that coordinately modulates gut microbial ecosystems, amino acid homeostasis, and neurotransmitter homeostasis. The findings provide novel insights into the gut-brain axis mechanisms of TCM formulations, offering a scientific foundation for developing microbiota-based intervention strategies for neurodevelopmental disorders.

Early life stress alters gut microbiota and increases the risk of neuropsychiatric disorders, including social deficits and anxiety, in the host. However, the role of gut commensal bacteria in early life stress-induced neurobehavioral abnormalities remains unclear. Using the maternally separated (MS) mice, our research has unveiled a novel aspect of this complex relationship. We discovered that the reduced levels of amino acid transporters in the intestine of MS mice led to low glutamine (Gln) levels in the blood and synaptic dysfunction in the medial prefrontal cortex (mPFC). Abnormally low blood Gln levels limit the brain's availability of Gln, which is required for presynaptic glutamate (Glu) and γ-aminobutyric acid (GABA) replenishment. Furthermore, MS resulted in gut microbiota dysbiosis characterized by a reduction in the relative abundance of Lactobacillus reuteri (L. reuteri). Notably, supplementation with L. reuteri ameliorates neurobehavioral abnormalities in MS mice by increasing intestinal amino acid transport and restoring synaptic transmission in the mPFC. In conclusion, our findings on the role of L. reuteri in regulating intestinal amino acid transport and buffering early life stress-induced behavioral abnormalities provide a novel insight into the microbiota-gut-brain signaling basis for emotional behaviors.

Obesity is one of the most serious public health challenges in the world. Obesity during early life has been associated with an increased risk of neurodevelopmental disorders, including deficits in learning and memory, yet the underlying mechanisms remain unclear. Here, we show that early life high-fat diet (HFD) feeding impairs hippocampus–dependent contextual/spatial learning and memory, and alters the gut microbiota, particularly by depleting Akkermansia muciniphila (A. muciniphila), in mice. Transplantation of the HFD microbiota confers hippocampus-dependent learning and memory deficits to mice fed a chow diet. Oral treatment of HFD-fed mice with the gut commensal A. muciniphila corrects gut permeability, reduces hippocampal microgliosis and proinflammatory cytokines (tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β) and IL-6) expression, and restores neuronal development and synapse plasticity, thus ameliorates defects in learning and memory. Interestingly, treatment of mice with lipopolysaccharide (LPS) mimics HFD-induced hippocampus-dependent cognitive impairment in chow-fed mice. In line with these findings, pharmacologic blockade of Toll-like receptor 4 (TLR4) signalling or antibiotics treatment both effectively prevent hippocampus-dependent learning and memory deficits in HFD-fed mice. Collectively, our findings demonstrate an unexpected pivotal role of gut microbiota in HFD-induced cognitive deficits and identify a potential probiotic therapy for obesity associated with cognitive dysfunction during early life.