Sleep enhancement mechanism of GABA-Producing lactic acid bacteria XBMU-SN-23 fermentation broth in a p-chlorophenylalanine-induced insomnia mouse model

γ-Aminobutyric acid (GABA) is an important neurotransmitter found abundantly in animals, plants, and microorganisms. Lactobacilli recognized as natural GABA producers, have garnered significant attention due to their safety and functionality. In our study, we aimed to isolate a high GABA-producing Lactobacillus strain from traditional fermented foods and investigate its growth characteristics, acid-producing capacity, and stress tolerance. Subsequently, a p-chlorophenylalanine (PCPA)-induced insomnia mouse model was established to evaluate the sleep-enhancing effects and underlying mechanisms of the strain's fermentation broth. We isolated six strains of GABA-producing lactic acid bacteria, among which strain XBMU-SN-23 exhibited the highest GABA production (2.150 g/L) as determined by high-performance liquid chromatography (HPLC) and was identified as Lactiplantibacillus plantarum via 16S rDNA sequencing. Treatment with XBMU-SN-23 fermentation broth significantly improved the quiet state of PCPA-induced insomniac mice. It mitigated PCPA-induced damage to hypothalamic neuronal cells, increased the levels of GABA, serotonin (5-HT), interleukin-1 (IL-1), and melatonin (MT), while simultaneously reducing glutamate (Glu) and dopamine (DA) in the serum and hypothalamus of the mice, thereby contributing to the restoration of neurotransmitter balance. Additionally, the treatment led to an increase in the expression of 5-HT_1A, GABA_AR_α1, and GABA_AR_γ2 receptor proteins, which play a crucial role in the regulation of molecular pathways and collectively enhance sleep quality. These findings support the sedative-hypnotic benefits of XBMU-SN-23 fermentation broth and provide a theoretical foundation for the future development of functional GABA-producing probiotic products.