Lactobacillales derived from traditional Xizang dairy products improve insomnia and restore neurotransmitter-metabolic profiles via gut microbiota in PCPA-induced mice

Insomnia remains a major public health challenge with limited safe treatment options. We demonstrate that mixed probiotics Lactobacillales ( Lactobacillus helveticus L551, Lacticaseibacillus paracasei L578, and Streptococcus thermophilus S709, group P) alleviates insomnia in PCPA-induced mice. P significantly reduced sleep latency and increased sleep duration, while ameliorating anxiety behaviors. The intervention attenuated insomnia-induced colonic structural damage and reactive oxygen species (ROS) accumulation, while restoring hippocampal CA1sp and hypothalamic Nissl body density, as well as normalizing brain glucose metabolism. Crucially, P intervention rebalanced neurotransmitter networks by enhancing serotonin (5-HT) synthesis while suppressing its catabolism, and reducing dopamine (DA) and norepinephrine (NE) levels. The P intervention significantly increased the abundance of Akkermansia and Acinetobacter compared to the insomnia model group (M). Notably, Acinetobacter exhibited significant positive correlations with N-acetylserotonin and gamma-aminobutyric acid (GABA) levels, while showing a significant negative correlation with 5-hydroxyindoleacetic acid (5-HIAA). These findings suggest its potential capacity to modulate tryptophan metabolism. In the M group, Staphylococcus was identified as the signature taxon, showing significant positive correlations with sleep latency and DA levels, and significant negative correlations with sleep duration and serotonin 5-HT levels. P intervention significantly reduced Staphylococcus abundance, concomitant with DA level normalization. In summary, Lactobacillales improve sleep quality and relieve anxiety in insomnia mice via modulating gut microbiota composition, thus regulating tryptophan metabolic pathways and sleep - related neurotransmitters.