MELATONIN AMELIORATES FLUORIDE INDUCED NEUROTOXICITY IN YOUNG RATS: AN IN VIVO EVIDENCE

Objective: Developing brain is highly vulnerable to environmental toxins. Recently, fluoride was declared as a developmental neurotoxin and heralded search for natural neuroprotectant. In the present study, we have evaluated the neuroprotective and anti-inflammatory efficacy of melatonin in fluoride induced neurotoxicity. Methods: Animals were divided into following groups; the first group was used as control. Groups 2, 3 and 4 were treated with melatonin (10 mg/kg BW), sodium fluoride (NaF 4 mg/kg BW) and NaF (4 mg/kg BW) plus melatonin (10 mg/kg BW) respectively. Young rats were orally administered their respective doses daily for 60 days. Biochemical and behavioral analysis were performed. The level of proinflammatory cytokine, tumor necrosis factor alpha (TNF-a) was also determined. Results: Data obtained showed that NaF significantly (p<0.001) increased thiobarbituric acid reactive substances (TBARS), ROS concentration and decreased the activities of glutathione (GSH) and glutathione peroxidase (GPx). On the other hand, melatonin plus NaF treated group showed significant decrease in the levels of TBARS and ROS while it increased the activities of antioxidant enzymes and glutathione content. In addition, melatonin significantly attenuated fluoride-induced increase in the TNF-α level of brain. Melatonin also prevented the cognitive deficit as shown by the increased retention latency in the passive avoidance task (p<0.001). Conclusion: The present study suggests that melatonin has therapeutic potential since it suppresses fluoride induced inflammation, cognitive impairment and oxidative stress in the brain.  Key words: Oxidative stress, Inflammation, Melatonin, TNF- α, Fluoride.