• Fluoride causes histopathological changes in C2C12 cells.
• Fluoride exposure damages ultrastructure in C2C12 cells.
• Fluoride exposure induces apoptosis in C2C12 cells.
• PI3K/AKT signaling pathway is involved in fluoride-induced apoptosis in C2C12 cells.

To investigate the mechanisms of fluoride-induced apoptosis, a fluoride-induced C2C12 skeletal muscle cell (C2C12 cell) model was established in this study, and the viability of the C2C12 cells was measured using an MTT assay. Cell morphological changes were observed via haematoxylin and eosin staining and transmission electron microscopy. Apoptosis was monitored through Hoechst staining. The mRNA and protein expression of PI3K, PDK1, AKT1, BAD, Bcl-2, Bax and caspase-9 were detected through real-time PCR and western blotting, respectively. The results showed that the survival rates of C2C12 cells decreased gradually with an increasing fluoride doses. The C2C12 cell structure was seriously damaged by fluoride, presenting with pyknosis, mitochondrial ridge disruption and swollen endoplasmic reticulum. Furthermore, the expression of mRNA in PI3K, BAD, Bcl-2, Bax and caspase-9 were significantly increased in the fluoride group (P <0.01), while the expression of PDK1 was markedly decreased (P <0.01). The expression of protein in BAD, Bcl-2 and Bax were significantly increased in the fluoride group (P <0.01), while the expression of PDK1 and P-AKT1 was markedly decreased (P <0.01). In conclusion, fluoride-induced apoptosis in C2C12 cells is related to the PI3K/AKT signaling pathway.