A novel effect of rivastigmine on presynaptic proteins and neuronal viability in a neurodegeneration model of fetal rat primary cortical cultures and its implication in Alzheimers disease

摘要

Alzheimer's disease (AD) is characterized by deposition of amyloid-beta peptide (Aβ) plaque, disrupted Aβ-precursor protein (APP) metabolism, hyperphosphorylation of Tau leading to neurofibrillary tangles and associated neurotoxicity. Moreover, there is synaptic loss in AD, which occurs early and precedes frank amyloidosis. The central cholinergic system is especially vulnerable to the toxic events associated with AD, and reduced acetylcholine (ACh) levels in specific brain regions is thought to be the central to memory deficits in AD. First-generation cholinesterase inhibitors (ChEIs) have provided only symptomatic relief to patients with AD by prolonging the action of remaining ACh with little or no change in the course of the disease. Some second-generation cholinesterase inhibitors are multi-functional drugs that may provide more than purely palliative results. To evaluate the effects of the dual AChE and butyrylcholinesterase (BuChE) inhibitor rivastigmine on key aspects of AD, embryonic day 16 rat primary cortical cultures were treated with rivastigmine under time and media conditions observed to induce neurodegeneration. Samples were subjected to Western blotting and immunocytochemistry techniques to determine what influence this drug may have on synaptic proteins and neuronal morphology. There was a strong increase in relative cell viability as a result of rivastigmine treatment. Significant dose-dependent increases were observed in the levels of synaptic markers SNAP-25 and synaptophysin, as well as the neuron specific form of enolase. Together with an observed enhancement of neuronal morphology, our results suggest a rivastigmine-mediated novel neuroprotective and/or neurorestorative effects involving the synapse. Our observations may explain the potential for rivastigmine to alter the course of AD, and warrant further investigations into using BuChE inhibition as a therapeutic strategy for AD, especially with regard to restoration of synaptic function.