Lactobacillus-rich microbiota promotes adaptive behavioral responses to multifactorial stress and preserves gut function, while antibiotic-induced dysbiosis suppresses these effects in mice.

The microbiota-gut-brain axis regulates gastrointestinal and neurobehavioral processes, including stress responses. Although stress and dysbiosis independently impact host physiology, their combined effects remain poorly understood. This study evaluated antibiotic-induced dysbiosis and multifactorial stress (MFS) effects on stress-coping and intestinal functionality by exploring the microbiota-gut-brain interaction. Male Swiss mice were divided into Control, Dysbiosis, MFS, and Dysbiosis+MFS groups. Dysbiosis was induced by administration of 10 mL/kg/day of an antibiotic cocktail containing Vancomycin 0.5 g/L, Metronidazole 1 g/L, Neomycin Sulfate 1 g/L, and Ampicillin 1 g/L. In MFS groups, mice underwent a 7-day multifactorial model (tail pressure, predator odor, water deprivation, 45° tilted cage, food deprivation, immobilization, and predator sound). Mice performed elevated plus maze, forced swimming, and tail suspension tests. Intestinal transit rate (%), fecal moisture content, and relative weights of the cecum and adrenal glands were assessed. Protein contents of occludin, claudin-1, and 5-HT4R in the colon, and glucocorticoid receptor in the hippocampus were determined. The microbiota profile of colorectal feces was analyzed by 16S rRNA sequencing. Dysbiosis and MFS interaction impacted the total sequences and alpha diversity of gut microbiota. Dysbiosis modified the composition of gut microbiota at the phylum, genus, and species levels, while MFS maintained Lactobacillus abundance. Dysbiosis induced intestinal dysfunction, while MFS attenuated intestinal barrier disruption without affecting other dysbiosis-induced effects. Dysbiosis and MFS individually decreased the weight gain of mice. Dysbiosis mitigated adaptive stress-coping behavior induced by MFS. Lactobacillus-rich microbiota promoted adaptive stress-coping behaviors and preserved gut function, while antibiotic-induced dysbiosis impaired both.