Exogenous melatonin restored the cyto-architectural integrity and biochemical activities of the cerebrum in sodium fluoride induced toxicity

The cerebrum is responsible for motor, sensory and autonomic activities of the human body, and it is believed that fluoride exposure to the biological system can impede these functions. Therefore, it is imperative to introduce melatonin to limit the extent of fluoride toxicity on the cerebrum and understand the mechanism involved in the aforementioned process. Thirty-two rats were randomly selected into 4 groups (n=8, per group). Groups I-IV received oral administration of 0.2ml of normal saline (NS), 500ppm of sodium fluoride (NaF), concurrent administration of sodium fluoride and melatonin (NaF+MLT), and sodium fluoride before melatonin (NaF-MLT) for fourteen days respectively. At the end of these treatments, the rats were euthanized and cerebral tissues were excised for histological, histochemical and biochemical analyses. Sodium fluoride distorted the shapes and size of the cells and caused constriction of the blood vessels, as well as presence of vacuolations in the cells of the pyramidal layer of the cerebral cortex. However, melatonin was able to restore the cytoarchitecture of cells of the pyramidal layer of the cerebral cortex when administered concurrently and after the administration of sodium fluoride (NaF) respectively. Also, melatonin regulated the activities of Superoxide dismutase, Malondialdehyde and Glutathione peroxidase in the cerebrum. Sodium fluoride causes neurodegeneration in the cerebral cortex, and exogenous melatonin can ameliorate the injury caused by sodium fluoride on the cerebral cortex.