The Possible Neuroprotective Effect of Silymarin against Aluminum Chloride-Prompted Alzheimer's-Like Disease in Rats

Alzheimer's disease (AD) is a worldwide rapidly growing neurodegenerative disease. Here, we elucidated the neuroprotective effects of silymarin (SM) on the hippocampal tissues of aluminum chloride (AlCl₃)-induced Alzheimer-like disease in rats using biochemical, histological, and ultrastructural approaches. Forty rats were divided into control, SM, AlCl₃, and AlCl₃ + SM groups. Biochemically, AlCl₃ administration resulted in marked elevation in levels of lipid peroxidation (LPO) and nitric oxide (NO) and decrease in levels of reduced glutathione (GSH), catalase (CAT), and superoxide dismutase (SOD). Moreover, AlCl₃ significantly increased tumor necrosis factor-α (TNF-α), interleukin-1beta (IL-1β), and acetylcholinesterase (AChE) activities. Furthermore, myriad histological and ultrastructural alterations were recorded in the hippocampal tissues of AlCl₃-treated rats represented as marked degenerative changes of pyramidal neurons, astrocytes, and oligodendrocytes. Additionally, some myelinated nerve fibers exhibited irregular arrangement of their myelin coats, while the others revealed focal degranulation of their myelin sheaths. Severe defects in the blood-brain barrier (BBB) were also recorded. However, co-administration of SM with AlCl₃ reversed most of the biochemical, histological, and ultrastructural changes triggered by AlCl₃ in rats. The results of the current study indicate that SM can potentially mend most of the previously evoked neuronal damage in the hippocampal tissues of AlCl₃-kindled rats.