Impact of antibiotic-induced gut dysbiosis model on bone mineralization and biomechanical properties in post-weaning rats

The gut microbiota plays a crucial role in regulating host metabolism and homeostasis through immune, endocrine, and metabolic pathways. This study investigated the impact of antibiotic-induced microbial disruption during the critical post-weaning period on bone biomechanical properties and mineral composition and evaluated whether fecal microbiota transplantation (FMT) could reverse these alterations in rats. Following weaning, Sprague Dawley rats were allocated to control (CON), dysbiosis (DYS), and FMT groups. To induce experimental intestinal dysbiosis, rats in the DYS and FMT groups were administered a broad-spectrum antibiotic mixture for 14 days following an established protocol. Subsequently, the FMT group received daily fecal suspensions from healthy donor rats for 10 days. At 8 weeks of age, tibial biomechanical integrity was assessed via three-point bending tests, and bone mineral composition was determined through crude ash, calcium (Ca), and phosphorus (P) analyses. The results demonstrated that antibiotic-induced DYS significantly reduced tibial ultimate force and stiffness while increasing displacement, indicating impaired bone mechanical integrity. In addition, DYS significantly decreased crude bone ash content as well as Ca and P levels. While histopathological examination did not reveal marked structural alterations among the groups, the FMT intervention partially restored bone mechanical strength and mineral composition toward control levels. These findings suggest that antibiotic-induced perturbations during early development negatively affect bone mineralization and biomechanics, while the partial recovery following FMT supports the concept of a functional gut–bone axis.