Studies looking at the dangers of fluoride are typically done when investigating fluoride in isolation. However, past research has shown this can grossly underestimate the true risk to public health as different neurotoxins in combination can result in unexpected and enhanced toxicological effects. In this study with 72 albino rats, researchers exposed animals to both fluoride and the pesticide rotenone either in isolation or combination. Levels of exposure included some which could equal fluoride blood levels found in humans. When animals were exposed to both compounds simultaneoulsy, scientists observed greater levels of damage than each chemical would have generated alone. This included a significant reduction in the protective antioxidant glutathione (which scavenges free radicals) as well as an increase in DNA damage found in subsequent brain tissue analysis. This demonstrates the importance of increasing studies that incorporate multiple neurotoxins simultaneously, otherwise known as synergism.
ABSTRACT:
Objective: Environmental toxins are known to be one of the important factors in the development of Parkinson's disease (PD). This study was designed to investigate the possible contribution of fluoride (F) exposure to oxidative stress and neurodegeneration in rats with PD induced by rotenone (ROT).
Materials and methods: A total of 72 Wistar albino male rats were used in the experiment and 9 groups were formed with 8 animals in each group. ROT (2 mg/kg) was administered subcutaneously (sc) for 28 days. Different doses of sodium fluoride (NaF) (25, 50 and 100 ug/mL) were given orally (po) for 4 weeks. Malondialdehyde (MDA), glutathione (GSH), nitric oxide (NO), oxidative DNA damage (8-OHdG) and cholinesterase (AChE/BChE) enzyme activities were evaluated in serum and brain tissue homogenates.
Results: Rats treated with ROT and NaF had significant increases in serum and brain MDA, NO content, and decreases in GSH. In addition, the combination of ROT and NaF triggered oxidative DNA damage and resulted in increased AChE/BChE activity.
Conclusions: Findings suggest that NaF and ROT may interact synergistically leading to oxidative damage and neuronal cell loss. As a result, we believe that exposure to pesticides in combination with NaF is one of the environmental factors that should not be ignored in the etiology of neurological diseases such as PD in populations in areas with endemic fluorosis.