Fluoride altered rat's blood testis barrier by affecting the F-actin via IL-1α

Fluoride is known to affect the pro-inflammatory cytokines in the testis. Most of the recent literatures cited that cytokines regulate the blood-testis-barrier (BTB). However, the involvement of cytokines in the fluoride induced toxicity in BTB remains unclear. In order to study this, 60 male Sprague-Dawley (SD) rats were taken and randomly divided into 5 groups which included four fluoride groups exposed to 0, 25, 50, and 100 mg/L NaF in distilled water and one positive control group. On the 29th day of fluoride exposure, the positive control group rats were administered 0.1% CaCl2 solution. Biotin tracer technology and transmission electron microscopy (TEM) analysis were applied to evaluate the function and ultra-structure of BTB. The expression levels of the BTB associated proteins, actin relative protein 3 (Arp3), interleukin-1 alpha (IL-1α), and transforming growth factor beta-3 (TGF-β3) were determined using Western blotting and Enzyme Linked Immunosorbent Assay (ELISA) respectively, meanwhile the actin filament (F-actin) was detected by fluorescent phalloidin conjugates. Our results revealed that the function and the ultra-structure of BTB in all the fluoride treated groups were damaged with a concomitant significant decreases in basal ectoplasmic specialization (basal ES), associated protein β-catenin, and F-actin. Moreover, Arp3 levels were significantly increased in 50 and 100 mg/L NaF groups. Meanwhile, IL-1α significantly increased in all the fluoride treated groups. In summary, we concluded that an increase in IL-1α induced by NaF significantly decreased the expression of F-actin and the organization of F-actin highly branched, which might facilitate the BTB's functional and ultra-structural variations.