Acute Exposure of Veterinary Antibiotic Tilmicosin Leads to Idiopathic Scoliosis-Like Vertebral Malformation Development Through Regulating PI3K-Akt Pathway in Zebrafish

The widespread use of veterinary antibiotics in animal husbandry, such as tilmicosin (TIL), poses potential threats to environment pollution and human health. In this study, we conducted acute TIL exposure experiment using zebrafish model to explore the toxicological effects. In the concentration range of 20–80 mg/L, TIL did not affect zebrafish body length development but induced idiopathic scoliosis (IS)-like symptoms accompanied by impaired mobility. IS predominantly occurs in adolescents, while the etiology remains unclear. Further studies showed that the combination of quercetin and luteolin effectively alleviated TIL-induced spinal curvature and motor suppression. To explore the underlying mechanism, we performed network pharmacology analysis and enriched the PI3K-Akt pathway. We validated that the expression of key target genes in the PI3K-Akt pathway were significantly activated after TIL exposure, while quercetin and luteolin treatment effectively inhibited the PI3K-Akt pathway activation. Further experiments revealed that TIL exposure decreased brain neural cell apoptosis, thereby causing an increase in neurocytes, interfering with motor ability, and promoting IS-like vertebral malformations, which were especially noticeable during movement. This study expands our understanding that TIL exposure may be a predisposing factor for IS occurrence and progression, while the combination of quercetin and luteolin combination could protect against IS-like symptom by regulating PI3K-Akt pathway. Graphical The experiments revealed that exposure to tilmicosin (TIL) induces the development of scoliosis-like deformities, which could be effectively alleviated by the quercetin and luteolin combination. Further mechanistic studies found that TIL exposure activates the PI3K-Akt pathway, resulting in reduced apoptosis of brain neurons and increased neural cells, which could be inhibited by quercetin and luteolin. As disturbed brain development is a predisposing factor for scoliosis, the TIL-induced abnormalities in brain neurodevelopment exacerbate the progression of scoliosis-like deformities and dyskinesia.