Nigella sativa protects against formaldehyde-induced neurotoxicity in the rat frontal cortex

Objectives: Nigella sativa (NS) is well known for its strong antioxidant properties. The aim of this study was to investigate the potential protective effect of NS, as a potent antioxidant and free radical scavenger, on the rat frontal cortex following formaldehyde (FA)-induced neuronal injury and oxidative stress. Methods: Forty albino rats were divided into four groups (n=10, each): control group received 1 ml distilled water, NS treated group crushed seeds of NS at a single daily dose of 180 mg/kg/bw orally for two weeks, FA-treated group 10 mg/kg/bw FA i.p. daily for two weeks, and FA and NS treated group received 10 mg/kg/bw FA i.p. followed by a single dose of NS (180 mg/kg/bw) orally for 2 weeks. The animals then were sacrificed and the frontal lobes were excised. Frontal cortex was stained with hematoxylen-eosin and caspase-3 immunohistochemistry to identify cell morphology and apoptosis. Lipid peroxide, nitric oxide, superoxide dismutase and glutathione levels were measured. Results: Histological examination revealed severe neurodegenerative changes in frontal cortex neurons in the FA-treated group as observed with hematoxylen-eosin and caspase-3 immunohistochemistry. However, these changes were partly prevented in the FA and NS-treated group. Apoptotic cell index in the frontal cortex decreased significantly in FA and NS treated rats compared to FA-treated rats. In the FA-treated group, lipid peroxide levels increased, while nitric oxide and glutathione levels decreased significantly compared with controls. In the FA + NS treated group, nitric oxide, glutathione and superoxide dismutase levels increased and lipid peroxide level decreased significantly when compared with the FA-treated group. Conclusion: NS administration protects frontal cortex neurons against oxidative damage induced by FA. Keywords: cerebral cortex; formaldehyde; neuronal injury; Nigella sativa; oxidative stress; rat