Neuroinflammation plays a crucial role in Alzheimer's disease (AD) pathogenesis. Apoptosis, along with impaired neurogenesis, has been linked to AD neurodegenerative cell death, likely due to overexpression of cyclooxygenase-2 (COX-2). We investigated whether the concurrent administration of celecoxib, a selective COX-2 inhibitor, with rivastigmine, the standard anti-Alzheimer, would enhance rivastigmine anti-Alzheimer activity in the aluminum chloride (AlCl3) Alzheimer's rat model. Male rats were randomly assembled into control (Cont), AlCl3-treated (Al), rivastigmine-treated (RIVA), celecoxib-treated (Celeco), and combined rivastigmine and celecoxib-treated (RIVA+Celeco) groups. They were studied for memory, and cognitive skills, along with evaluating hippocampal acetylcholinesterase (AChE) activity. Hippocampal neuropathology, besides apoptosis, astroglial injury, and neurogenesis, were assessed through examining the expression of their related protein markers; activated caspase-3, glial fibrillary acidic protein (GFAP), and nestin. Celecoxib, rivastigmine, and their combination attenuated AlCl3induced intellectual impairment and the associated neurodegenerative changes. However, the combination therapy had no additional neuroprotective advantage over rivastigmine alone, except for the enhancement of neurogenesis and suppression of apoptosis in the AL-intoxicated rats. As compared to rivastigmine, the efficacy of celecoxib in combination with rivastigmine confers neuroprotection only at the cellular level, enhancement of neurogenesis, and suppression of apoptosis, without having a mitigating effect on Al-induced cognitive impairment.

No abstract

Alzheimer’s disease (AD) is one of the leading causes of dependence and disability among the elderly worldwide. The traditional anti-Alzheimer medication, rivastigmine, one of the cholinesterase inhibitors (ChEIs), fails to achieve a definitive cure. Neuroinflammation plays a central role in AD pathogenesis. We tested the hypothesis that naproxen, a non-steroidal anti-inflammatory drug (NSAID), administration to the rivastigmine-treated aluminum chloride (AlCl3), Alzheimer's rat model, could provide an additive neuroprotective effect compared to rivastigmine alone. The studied groups were control (Cont), AlCl3 treated (Al), rivastigmine treated (RIVA), naproxen treated (Napro), and combined rivastigmine and naproxen treated (RIVA + Napro). Rats’ memory, spatial learning, and cognitive behavior were assessed followed by evaluation of hippocampal acetylcholinesterase (AChE) activity. Hippocampal and cerebellar histopathology were thoroughly examined. A marker of astroglial injury; glial fibrillary acidic protein (GFAP), the apoptosis maker; activated caspase-3 and the neuroepithelial stem cells marker; nestin expressions were immunohistochemically assayed. AD rats displayed significantly impaired memory and cognitive function, augmented hippocampal AChE activity, massive neurodegeneration associated with enhanced astrogliosis, apoptosis, and impaired neurogenesis. Rivastigmine, naproxen, and their combination decreased hippocampal AChE activity, mitigated behavioral and neuropathological changes in Al-intoxicated rats, possibly through downregulation of activated caspase-3 and upregulation of nestin. Except for the enhancement of neurogenesis and suppression of apoptosis, the combination therapy had no additional neuroprotective benefit over rivastigmine-only therapy. Naproxen's efficacy was demonstrated by its ability to act at the cellular level, enhance neurogenesis, and suppress apoptosis without having an additional mitigating impact in Al-induced cognitive impairment.