Behavioral Alterations in Antibiotic-Treated Mice Linked to Gut Microbiota Dysbiosis: Insights from 16S rRNA and Metabolomics

Asma Bibi ¹ Famin Zhang ¹ Jilong Shen ¹ Ahmad Ud Din ² Yuanhong XU ^3*

• ¹ Anhui Medical University, Hefei, Anhui Province, China
• ² Plants for Human Health Institute, North Carolina State University, Kannapolis, North Carolina, United States
• ³ First Affiliated Hospital of Anhui Medical University, Hefei, China

The gut and brain interact through various metabolic and signaling pathways, each influencing mental health. Gut dysbiosis caused by antibiotics is a well-known phenomenon that has serious implications for gut microbiota-brain interactions. Even though antibiotics disrupt the gut microbiota's fundamental structure, the mechanisms that modulate the response and their impact on brain function are still unclear. It is imperative to comprehend and investigate crucial regulators and factors that play important roles. We aimed to study the effect of long-term antibiotic-induced disruption of gut microbiota, host metabolomes, and brain function and especially, determine the basic interactions between them, by treating the C57BL/6 mice with two different most commonly used antibiotics, Ciprofloxacin and Amoxicillin. Anxiety-like behavior was confirmed by the elevated plus-maze test and open field test. Gut microbes and their metabolite profile in the faecal, serum, and brain samples were determined by 16S rRNA sequencing and untargeted metabolomics. In our results, long-term antibiotic treatment exerted anxiety-like effects. Faecal microbiota and metabolites status revealed that the top 5 genera found were Lactobacillus, Bacteroides, Akkermansia, Ruminococcus_gnavus_group, and (norank_f_Muribaculaceae) unclassified. The concentration of serotonin, L-Tyrosine, 5-Hydroxy-L-tryptophan, L-Glutamic acid, L-Glutamate, 5-Hydroxyindole acetic acid, and dopaminergic synapsis was comparatively low while adenosine was high in antibiotic-treated mice. Meanwhile, The KEGG enrichment analysis of serum and brain samples showed that amino acid metabolism pathways such as tryptophan metabolism, threonine metabolism, serotonergic synapsis, methionine metabolism, and neuroactive ligand-receptor interaction, were significantly decreased in antibiotic-treated mice.Our study demonstrates that long-term antibiotic use induces gut dysbiosis and alters metabolic responses, leading to the dysregulation of brain signaling molecules and anxiety-like behavior.These highlight the complex interactions between gut microbiota and metabolic functions, providing new insights into microbial influences on gut-brain communication.