Behavioral and histological study on the neuroprotective effect of thymoquinone on the cerebellum in AlCl3-induced neurotoxicity in rats through modulation of oxidative stress, apoptosis, and autophagy

Alzheimer disease (AD) is a neurodegenerative condition. Thymoquinone (TQ) is a natural compound that possesses beneficial biological effects on the brain. The present study evaluates the protective impact of TQ on the cerebellum in rats with AlCl3-induced Alzheimer's disease. Four groups were utilized. Control: 20 rats that were subdivided into two subgroups. Ia: received distilled water for 4 weeks. Ib: received corn oil via oral gavage (1 ml/kg daily) for 4 weeks. TQ group: 10 rats received TQ in corn oil via oral gavage (20 mg/kg daily) for 4 weeks. AD group:10 rats received AlCl3 in distilled water via oral gavage (300 mg/kg daily) for 4 weeks. AD & TQ group: 10 rats received both AlCl3 & TQ for 4 weeks. The grip period in the rotarod test decreased, escape latency in first three days and the entry latency period to the quadrant with the removed escape platform in the Morris water maze test increased in AD group, but when TQ was administered concurrently, there was a noteworthy improvement. Meanwhile, when compared to AD group, the addition of TQ showed a significant decrease (P < 0.05) in levels of malondialdehyde (MDA) and nitric oxide (NO), associated with a significant increase (P < 0.05) in reduced glutathione (GSH) level. Furthermore, AD & TQ group exhibited substantial preservation of the cerebellum's histological structure, the Purkinje cells number and transverse diameter showed a high significant increase (P < 0.001) and a significant increase (P < 0.05), respectively in comparison to the AD group. Using TQ showed improvement in behavioral tests, biochemical and histological findings. Thus, TQ might have therapeutic effects on Alzheimer's disease.