R. M. Aljarari, A. E. Bawazir‎ ‎

Abstract

Alzheimer's disease (AD) is one of the most common dementia causes especially in elders. Black raisins (Vitis vinifera) have memory-enhancing effects. This study was designed to investigate the effect of oral administration of black raisins (V. vinifera) on aluminum-chloride (AlCl₃) induced AD in male albino rats. Forty adult male Albino rats were equally and randomly divided into five groups, 8 rats in each. The rats of the first group received a vehicle and served as controls. The animals of the second group received raisin (5 g per rat/day) orally for 8 weeks. The rats in the third group were treated with AlCl₃ (model of AD) (100 mg/kg BW/day) for 8 weeks. The animals of the fourth group were treated with AlCl₃ (100 mg/kg BW/day) and raisin. The animals of the fifth group received rivastigmine (0.3 mg/kg BW/day) and AlCl₃ (100 mg/kg BW/day) orally for 8 weeks. After eight weeks, the behavioral test (maze learning test) was performed on all rats to assess learning and memory. Moreover, acetylcholinesterase (AchE) activity, some neurotransmitter levels [dopamine (DA), norepinephrine (NE), gamma-aminobutyric acid (GABA)], and oxidative stress [reduced glutathione (GSH), superoxide dismutase (SOD), oxidase glutathione (GSSG), and lipid peroxidation (LPO)] were estimated in the cortex and hippocampus homogenate. The histopathological studies were also made in the hippocampus area. The results showed that aluminum exposure significantly decreased the learning and memory in the maze-learning test as revealed by increase in elapsed time and error number in the maze. Significant increase of cortex and hippocampus homogenate levels of AchE and LPO, but a significant decrease in DA, NE, GABA, GSH, GSSG, and SOD were observed in rats subjected to AlCl₃. Histopathological evaluations of hippocampus sections of rats treated with AlCl₃ showed severe alterations including the increase of degenerated cells with structural damage. The treatment of rats with raisin or rivastigmine for 8 weeks showed a pronounced attenuation on the damage caused by AlCl₃ associated with the improvement of behavioral, biochemical, and histopathological alterations. This study suggested that chronic oral administration of black raisin had neuroprotective effects and improved learning and memory in AD animal models. These actions were done due to the antioxidant constituents of raisin.