Modulatory effect of simvastatin on redox status, caspase-3 expression, p-protein kinase B (p-Akt), and brain-derived neurotrophic factor (BDNF) in an ethanol-induced neurodegeneration model

Roles of Oxidative Stress and Autophagy in Alcohol-Mediated Brain Damage

Excessive alcohol consumption significantly impacts human health, particularly the brain, due to its susceptibility to oxidative stress, which contributes to neurodegenerative conditions. Alcohol metabolism in the brain occurs primarily via catalase, followed by CYP2E1 pathways. Excess alcohol metabolized by CYP2E1 generates reactive oxygen/nitrogen species (ROS/RNS), leading to cell injury via altering many different pathways. Elevated oxidative stress impairs autophagic processes, increasing post-translational modifications and further exacerbating mitochondrial dysfunction and ER stress, leading to cell death. The literature highlights that alcohol-induced oxidative stress disrupts autophagy and mitophagy, contributing to neuronal damage. Key mechanisms include mitochondrial dysfunction, ER stress, epigenetics, and the accumulation of oxidatively modified proteins, which lead to neuroinflammation and impaired cellular quality control. These processes are exacerbated by chronic alcohol exposure, resulting in the suppression of protective pathways like NRF2-mediated antioxidant responses and increased susceptibility to neurodegenerative changes in the brain. Alcohol-mediated neurotoxicity involves complex interactions between alcohol metabolism, oxidative stress, and autophagy regulation, which are influenced by various factors such as drinking patterns, nutritional status, and genetic/environmental factors, highlighting the need for further molecular studies to unravel these mechanisms and develop targeted interventions.

HMG-CoA reductase inhibitor simvastatin ameliorates trimethyltin neurotoxicity and cognitive impairment through reversal of Alzheimer's-associated markers

Alzheimer's disease (AD) is a prevalent neurodegenerative disorder in elderly. The neurotoxicant trimethyltin (TMT) induces neurodegenerative changes, as observed in AD. The 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitor simvastatin (SV) has shown protective and promising therapeutic effects in neurological disorders such as AD and Parkinson's disease. The present study aimed to assess neuroprotective effect of simvastatin (SV) against trimethyltin (TMT) memory decline and hippocampal neurodegeneration. For inducing AD-like phenotype, rats were i.p. injected with TMT at 8 mg/kg and were treated with simvastatin daily for 3 weeks at 10 or 30 mg/kg. Our analysis of data indicated that simvastatin-treated TMT group has lower learning and memory deficits in behavioral tasks comprising Barnes maze, Y maze, and novel object discrimination (NOD). In addition, hippocampal inflammatory, oxidative, and apoptotic factors were attenuated besides reduction of acetylcholinesterase (AChE) activity and Alzheimer's pathology factors including presenilin-1 and hyperphorphorylated Tau (p-Tau) upon simvastatin. Moreover, simvastatin treatment of TMT group inverted hippocampal changes of Wnt, β-catenin, ERK, and Akt, ameliorated astrocytic and microglial reactivity, and also prevented injury of CA1 neurons. This study unraveled that simvastatin is capable to prevent TMT-induced Alzheimer's-like phenotype in association with Wnt/β-catenin/ERK/Akt as well as restraining hippocampal neurodegeneration.

An Approach to Apply BDNF Targeting Fe3O4-Based Nanoparticles as Multifunctional Anti-Alzheimer Agents

To search for novel anti-Alzheimer agents, multifunctional Fe3O4-based nanoparticles (FSSIO) is designed and prepared which contain ferulic acid (FA) and Simvastatin linked to the surface of Fe3O4 particles. In vitro tests confirmed that FSSIO possessed favorable biocompatibility and a pronounced ability to penetrate blood brain barrier. The FA moiety endowed the particles with remarkable antioxidant and anti-inflammatory properties, and effectively protected neuron cells from the toxicity induced by Aβ. Moreover, the Simvastatin pharmacophore assists the particles up-regulate the expression level of BDNF and significantly promotes the expression levels of p-TrkB, p-ERK, p-PI3K and Akt, which consequently leads to the neurite outgrowth via regulating PI3K/ATK and TrkB-mediated signaling pathway. More importantly, in the Morris water maze test, FSSIO shows excellent activity to enhance the learning and memory retention of AD model rats.

Simvastatin rescues memory and granule cell maturation through the Wnt/β-catenin signaling pathway in a mouse model of Alzheimer's disease

We previously showed that simvastatin (SV) restored memory in a mouse model of Alzheimer disease (AD) concomitantly with normalization in protein levels of memory-related immediate early genes in hippocampal CA1 neurons. Here, we investigated age-related changes in the hippocampal memory pathway, and whether the beneficial effects of SV could be related to enhanced neurogenesis and signaling in the Wnt/β-catenin pathway. APP mice and wild-type (WT) littermate controls showed comparable number of proliferating (Ki67-positive nuclei) and immature (doublecortin (DCX)-positive) granule cells in the dentate gyrus until 3 months of age. At 4 months, Ki67 or DCX positive cells decreased sharply and remained less numerous until the endpoint (6 months) in both SV-treated and untreated APP mice. In 6 month-old APP mice, dendritic extensions of DCX immature neurons in the molecular layer were shorter, a deficit fully normalized by SV. Similarly, whereas mature granule cells (calbindin-immunopositive) were decreased in APP mice and not restored by SV, their dendritic arborizations were normalized to control levels by SV treatment. SV increased Prox1 protein levels (↑67.7%, p < 0.01), a Wnt/β-catenin signaling target, while significantly decreasing (↓61.2%, p < 0.05) the upregulated levels of the β-catenin-dependent Wnt pathway inhibitor DKK1 seen in APP mice. In APP mice, SV benefits were recapitulated by treatment with the Wnt/β-catenin specific agonist WAY-262611, whereas they were fully abolished in mice that received the Wnt/β-catenin pathway inhibitor XAV939 during the last month of SV treatment. Our results indicate that activation of the Wnt-β-catenin pathway through downregulation of DKK1 underlies SV neuronal and cognitive benefits.