Behavioral Profile and Gut Microbiota Composition in Rats with Different Nervous System Excitability

Previous studies have shown that two rat strains selected by the excitability threshold of the nervous system exhibit differences in response to prolonged emotional-pain stress at behavioral, neurobiological, and molecular genetic levels, as well as specific changes in gut microbiota composition, suggesting a potential link between genetic factors, microbiota, and behavioral disorders. The aim of this study is to analyze the gut microbiota and behavioral profiles in intact rats with high (HT) and low (LT) excitability thresholds to identify key differences driven by their genetic characteristics. The behavior of intact rats from two strains was analyzed in the Open Field and Elevated Plus Maze, and microbiota analysis in stool samples was conducted using 16S rRNA gene amplicon sequencing. Behavioral analysis revealed that high-excitability (LT) rats exhibited higher activity and reduced freezing in the Elevated Plus Maze compared to low-excitability (HT) rats. While alpha diversity indices of gut microbiota showed no significant inter-strain differences, beta diversity analysis revealed significant differences in microbial profiles between HT and LT rats. LT rats had a significantly higher abundance of Lactobacillus and Faecalibacterium genera compared to HT animals, whereas HT rats demonstrated a higher relative abundance of Romboutsia, Eubacterium, and Turicibacter genera. Thus, the data of behavioral and microbiota analyses highlight a potential link between genetic factors, gut microbiota profiles, and the unique physiological and behavioral traits of rat strains selected for the excitability threshold of the nervous system.