Lactobacillus rhamnosus GG ameliorates noise-induced cognitive deficits and systemic inflammation in rats by modulating the gut-brain axis

Abstract

BackgroundEnvironmental noise exposure is linked to neuroinflammation and imbalance of the gut microbiota. Promoting gut microbiota homeostasis may be a key factor in relieving the deleterious non-auditory effects of noise. This study aimed to investigate the effect of Lactobacillus rhamnosus GG (LGG) intervention on noise-induced cognitive deficits and systemic inflammation in rats.MethodsLearning and memory were assessed using the Morris water maze, while 16S rRNA sequencing and gas chromatography-mass spectrometry were used to analyze the gut microbiota and short-chain fatty acid (SCFA) content. Endothelial tight junction proteins and serum inflammatory mediators were assessed to explore the underlying pathological mechanisms.ResultsThe results indicated that Lactobacillus rhamnosus GG intervention ameliorated noise-induced memory deterioration, promoted the proliferation of beneficial bacteria, inhibited the growth of harmful bacteria, improved dysregulation of SCFA-producing bacteria, and regulated SCFA levels. Mechanistically, noise exposure led to a decrease in tight junction proteins in the gut and hippocampus and an increase in serum inflammatory mediators, which were significantly alleviated by Lactobacillus rhamnosus GG intervention.ConclusionTaken together, Lactobacillus rhamnosus GG intervention reduced gut bacterial translocation, restored gut and blood-brain barrier functions, and improved gut bacterial balance in rats exposed to chronic noise, thereby protecting against cognitive deficits and systemic inflammation by modulating the gut-brain axis.

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“…Beneficial bacteria play a vital role in SCFA production, which directly maintains intestinal homeostasis. , Notably, the SCFA content was significantly lower in the HFD group than in the control group, and these changes were dramatically reversed by WEPE, ALA, and GA treatments (Table ). Although the Firmicutes / Bacteroidetes ratio was not effectively altered (Figure A–D), the relative abundances of some beneficial bacteria, such as Romoutsia , Turicibacter , Allobaculum , Bifidobacterium , Coriobacteriaceae_UCG-002 , and Parasutterella , were dominant in the WEPE, ALA, and GA groups (Figure ).…”

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“…13 ). Treatment of noise-exposed rats with Lactobacillus rhamnosus GG prevented cognitive deficits and systemic inflammation by modulating the gut-brain axis (e.g., restoration of behavior and corticosterone levels) [ 329 ]. Additionally, a recent study found higher gut microbial diversity in sparrows living in a noisy environment, suggesting that urban sparrows have higher bacterial wealth than their rural counterparts, which was also associated with increased corticosterone and decreased food intake [ 330 ].…”

“…In two studies, noise-induced inflammation was prevented in mice with Nox2 deletion [ 16 , 363 ]. Furthermore, antioxidant pharmacological activation/induction of the nuclear factor E2 related factor-2 (NRF-2)/heme oxygenase 1 (HO-1) axis [ 461 ], probiotic therapy [ 329 ], and treatment with the antibiotic minocycline [ 462 ] all been shown to inhibit noise-induced inflammation. The hypothesized mechanisms behind noise-induced inflammation are presented in Fig.…”