Neuroprotective effect of quercetin nanoparticles: A possible prophylactic and therapeutic role in alzheimer's disease.

BACKGROUND:Alzheimer's disease (AD) is the most common cause of dementia in elderly. Quercetin is a well-known flavonoid with low bioavailability. Recently, quercetin nanoparticles (QNPs) has been shown to have a better bioavailability. AIMS:This study aimed to investigate the protective and therapeutic effects of QNPs in Aluminum chloride (AlCl3) induced animal model of AD. MATERIALS AND METHODS:AD was induced in rats by oral administration of AlCl3 (100 mg/kg/day) for 42 days. QNPs (30 mg/kg) was given along with AlCl3 in the prophylactic group and following AD induction in the treated group. Hippocampi were harvested for assessments of the structural and ultrastructural changes using histological and histochemical approaches. RESULTS AND DISCUSSION:AD hippocampi showed a prominent structural and ultrastructural disorders both neuronal and extraneuronal. Including neuronal degeneration, formation of APs and NFTs, downregulation of tyrosine hydroxylase (TH), astrogliosis and inhibition of the proliferative activity (all P ≤ 0.05). Electron microscopy showed signs of neuronal degeneration with microglia and astrocyte activation and disruption of myelination and Blood Brain Barrier (BBB). Interestingly, QNPs administration remarkably reduced the neuronal degenerative changes, APs and NFTs formation (all P ≤ 0.05). Furthermore, it showed signs of regeneration (all P ≤ 0.05) and upregulation of TH. The effect was profound in the prophylactic group. Thus, QNPs reduced the damaging effect of AlCl3 on hippocampal neurons at the molecular, cellular and subcellular levels. CONCLUSION:For the best of our knowledge this is the first study to show a prophylactic and therapeutic effect for QNPs in AD model. This might open the gate for further research and provide a new line for therapeutic intervention in AD.