Abstract
Alzheimer's disease (AD), the most common neurodegenerative disorder, is characterized by behavioral, cognitive, and progressive memory impairments. Extensive neuronal loss, extracellular accumulation of insoluble senile amyloid-β (Aβ) plaques, and intracellular neurofibrillary tangles (NFTs) are the major pathological features. The present study aimed to investigate the therapeutic effect of donepezil (DON) and pentoxifylline (PTX) in combination to combat the neurodegenerative disorders (experimental AD) induced by CuSO4 intake in experimental rats. Thirty adult male Wistar rats (140-160 g) were used in this study. AD was first induced in rats by CuSO4 supplement to drinking water (10 mg/L) for 14 weeks. The AD group received no further treatment. Oral treatment with DON (10 mg/kg/day), PTX (100 mg/kg/day), or DON + PTX for the other three groups was started from the 10th week of CuSO4 intake for 4 weeks. Cortex markers like acetylcholine (ACh), acetylcholinesterase (AChE), total antioxidant capacity (TAC), and malondialdehyde (MDA) and hippocampus markers like β-amyloid precursor protein cleaving enzyme 1 (BACE1), phosphorylated Tau (p-tau), Clusterin (CLU), tumor necrosis factor-α (TNF-α), caspase-9 (CAS-9), Bax, and Bcl-2 were measured. The histopathology studies were done by using hematoxylin and eosin and Congo red stains as well as immunohistochemistry for neurofilament. CuSO4 induced adverse histological and biochemical changes. The histological injury in the hippocampus was inhibited following the administration of the DON and PTX. The brain tissue levels of AChE, MDA, BACE1, p-tau, CLU, CAS-9, Bax, and TNF-α were significantly increased, while brain tissue levels of ACh, TAC, and Bcl-2 were significantly decreased in CuSO4-treated rats as compared with the untreated control group. The effects induced by either DON or PTX on most studied parameters were comparable. Combined treatment of DON and PTX induced remarkable results compared with their individual use. However, more clinical and preclinical studies are still required to further confirm and prove the long-term efficacy of such combination.