RESUMO
OBJECTIVES: Hypercholesterolemia is correlated with brain amyloid-ß (Aß) deposition and impaired cognitive functions and contributes to Alzheimer's disease. Effects of cholesterol-lowering dill tablets and aqueous extract of Ocimum basilicum L. (basil) on learning and memory and hippocampus fatty acid composition were examined. mRNA levels of the genes involved in cholesterol homeostasis were also determined in high-cholesterol diet (HCD) fed rats. MATERIALS AND METHODS: Forty male Wistar rats were allocated to 4 groups: rats fed chow diet (C); rats fed high-cholesterol (2%) diet (HCD); rats treated with HCD+300 mg/kg dill tablets (HCD+Dill); and finally, rats fed HCD and treated with 400 mg/kg basil aqueous extract (HCD+basil). Treatment was carried out for 16 weeks. Hippocampus Aß(1-42) level was determined. Spatial and passive avoidance tests were used to examine cognitive functions. Hippocampal FA composition was assessed by gas chromatography. Basil aqueous extract was analyzed by GC-double mass spectroscopy (GC-MS/MS) and expression of LXR-α, LXR-ß, and ABCA1 genes was assessed by qRT-PCR. RESULTS: Dill tablets and basil extract remarkably ameliorated serum cholesterol (P<0.001), retarded hippocampal accumulation of Aß, and attenuated HCD-induced memory impairment. Hippocampus FA composition did not change but serum cholesterol was found positively correlated with hippocampus Aß(1-42) (P<0.001), total n 6 PUFA (P=0.013), and Aß(1-42) showed correlation with the ratio of n6 to n3 PUFA. At least 70 components were identified in basil aqueous extract. CONCLUSION: Dill tablets and aqueous extract of basil attenuated the hypercholesterolemia-induced memory impairment by lowering serum cholesterol and hippocampus amyloid deposits, and probably beneficial in AD adjuvant therapy.
RESUMO
High-cholesterol diet (HCD) is correlated with Alzheimer's disease (AD) and impairment of memory. This study investigated beneficial therapeutic effects of Dill tablet and Ocimum basilicum (Basil) aqueous extract on hypercholesterolemia-induced cognitive deficits and oxidative stress in hippocampus tissues of rats. Hippocampal Aß(1-42) level was measured. The gene expression levels of superoxide dismutase and inducible-nitric oxide synthase were determined in hippocampus. Cognitive functions were examined and oxidative status was evaluated in serum and hippocampus. Phytochemical properties and in vitro antioxidant activity of Basil extract were assessed. HCD significantly increased serum cholesterol, induced deposition of Aß plaque, altered hippocampus morphology, and impaired memory function, whereas receiving Basil extract or Dill tablet increased antioxidant potency in serum and hippocampus and normalized HCD-induced deleterious effects. Basil extract and Dill tablet may exhibit their beneficial effects in AD by lowering serum cholesterol and evoking antioxidant system in the brain. PRACTICAL APPLICATIONS: Dill tablet and Basil aqueous extract lowered serum cholesterol in hypercholesterolemic animal models, therefore, they can be used as hypocholesterolemic agents. These edible herbs significantly retarded deposition of Aß plaque and normalized hippocampal morphology, thus, they favorably protected hippocampus tissue from deleterious effects-induced by hypercholesterolemia. Dill tablet and Basil aqueous extract also corrected oxide-redox balance and normalized HCD-induced oxidative stress to some extent and significantly improved impairments in learning and memory suggesting that these medicinal plants can be considered as surrogate therapeutic agents for the synthetic medicines in the treatment of AD and in postponement of its complications.