Protein and mRNA expression of Shh, Smo and Gli1 and inhibition by cyclopamine in hepatocytes of rats with chronic fluorosis

• Excess fluoride may be able to participate in the pathway of Shh signaling.
• The Shh signaling pathway in hepatocytes of fluorosis rats can be blocked by cyclopamine.
• Interaction between Shh and other cell signaling pathways may be due to liver injury by fluorosis.

In order to investigate the Sonic hedgehog (Shh) signaling pathway and the effect of cyclopamine in rat hepatocytes with chronic fluorosis, 48 Wistar rats were randomly divided into 4 groups. The control group was provided with tap water in which the fluorine concentration was <1 mg/L, while the remaining three groups were provided with water containing sodium fluoride (NaF) at a concentration of 50 mg/L. After 6 months, the blocking and blocking control groups were injected intraperitoneally once every 2 days for 6 days with 10 mg/kg cyclopamine or dimethyl sulfoxide, respectively. The urinary and skeletal fluoride contents were determined by the ion selective electrode method. Levels of aspartate transaminase (AST), alanine transaminase (ALT), total protein (TP) and albumin (Alb) in the serum were determined by using autobiochemical machine. Histological changes in liver tissue were evaluated with Hematoxylin & Eeosin (H&E) staining using light microscopy. The protein and mRNA expression of Shh, Smo and Gli1 in hepatocytes of experimental animals was determined by immunohistochemistry (IHC), Western blotting (Wb) and Real-time quantitative PCR (RT-qPCR). Fluoride content of the urine and bone was increased in the fluorosis and blocking groups compared to those in the control group (P < 0.05), while fluoride content in the blocking group was decreased compared to the fluorosis and blocking control groups (P < 0.05). The expression of Shh, Smo and Gli1 at the mRNA and protein levels was significantly increased in hepatocytes from the fluorosis and blocking control groups compared with the control group, and expression in the blocking group was lower than that of the fluorosis and blocking control groups. The difference between any two groups was considered to be statistically significant (P < 0.05). Taken together, our study indicates that the expression of Shh, Smo and Gli1 at the protein and mRNA level in hepatocytes of rats with chronic fluorosis can be increased by fluoride and may be inhibited by cyclopamine and that the Shh signaling pathway plays an important role in the liver pathogenesis caused by fluorosis.