Simvastatin ameliorates cognitive impairments via inhibition of oxidative stress‑induced apoptosis of hippocampal cells through the ERK/AKT signaling pathway in a rat model of senile dementia

Why antidiabetic drugs are potentially neuroprotective during the Sars-CoV-2 pandemic: The focus on astroglial UPR and calcium-binding proteins

We are living in a terrifying pandemic caused by Sars-CoV-2, in which patients with diabetes mellitus have, from the beginning, been identified as having a high risk of hospitalization and mortality. This viral disease is not limited to the respiratory system, but also affects, among other organs, the central nervous system. Furthermore, we already know that individuals with diabetes mellitus exhibit signs of astrocyte dysfunction and are more likely to develop cognitive deficits and even dementia. It is now being realized that COVID-19 incurs long-term effects and that those infected can develop several neurological and psychiatric manifestations. As this virus seriously compromises cell metabolism by triggering several mechanisms leading to the unfolded protein response (UPR), which involves endoplasmic reticulum Ca²⁺ depletion, we review here the basis involved in this response that are intimately associated with the development of neurodegenerative diseases. The discussion aims to highlight two aspects—the role of calcium-binding proteins and the role of astrocytes, glial cells that integrate energy metabolism with neurotransmission and with neuroinflammation. Among the proteins discussed are calpain, calcineurin, and sorcin. These proteins are emphasized as markers of the UPR and are potential therapeutic targets. Finally, we discuss the role of drugs widely prescribed to patients with diabetes mellitus, such as statins, metformin, and calcium channel blockers. The review assesses potential neuroprotection mechanisms, focusing on the UPR and the restoration of reticular Ca²⁺ homeostasis, based on both clinical and experimental data.

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.

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

Neurodegenerative diseases are a common cause of morbidity and mortality worldwide, with oxidative stress, inflammation, and protein aggregation representing the main underlying mechanisms that ultimately lead to cell death. Ethanol has shown strong neurodegenerative consequences in experimental animal brains. Statins are a class of lipid-lowering drugs with many pleotropic effects. Therefore, the aim of the present study was to explore the modulatory effect of simvastatin (10 mg·kg^-1·day^-1) before and after the development of neurodegeneration (for 55 and 25 days, respectively) on redox state, caspase-3 expression, p-protein kinase B (p-Akt), and brain-derived neurotrophic factor (BDNF) in ethanol-induced (15% ethanol solution for 55 days) neurodegeneration. Seventy female Albino Swiss mice were included and randomly divided into five groups: C, control group; E, ethanol group; ES, group treated with simvastatin from the first day of ethanol intake; E + S, group treated with simvastatin after neurodegeneration development; and S, simvastatin group. Administration of simvastatin from the first day improved the biochemical changes, suppressed apoptosis, and induced autophagy and neurogenesis; however, its administration after the development of neurodegeneration resulted in partial improvement. The histopathological findings confirmed the biochemical changes. In conclusion, simvastatin has a neuroprotective effect against the development of ethanol-induced neurodegeneration and its progression.

Telmisartan and Rosuvastatin Synergistically Ameliorate Dementia and Cognitive Impairment in Older Hypertensive Patients With Apolipoprotein E Genotype

Objective: To investigate the effect of telmisartan, rosuvastatin, or their combination on dementia and to understand the impact of apolipoprotein E (APOE) genotype on the effect of the medications in older patients with hypertension.

Methods: This is a double-blind, randomized, and placebo-controlled trial using a 2 × 2 factorial design. Between April 2008 and November 2010, 1,244 hypertensive patients aged ≥60 years without cognitive impairment were recruited from communities in six cities in Shandong area, China. Patients were randomized into telmisartan and rosuvastatin administration after a 2-week washout period. APOE genotype was identified at the baseline. Possible dementia was determined using the combination of the global cognitive function and Assessment of the Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE).

Results: Over an average follow-up of 7 [interquartile range (IQR): 6.7–7.2] years, telmisartan and rosuvastatin significantly reduced the cognitive impairment progression and the incidence of dementia. There was a synergistic interaction between telmisartan and rosuvastatin to reduce the cognitive impairment and the incidence of dementia (P_adjusted < 0.001). The cognitive impairment progression and the risk of dementia were higher in the hypertensive patients with APOE ε4 allele than in those without APOE ε4 allele. Rosuvastatin medication significantly alleviated the cognitive impairment progression and the risks of dementia in patients with APOE ε4 allele.

Conclusion: The combination of telmisartan and rosuvastatin might be an effective prevention and/or treatment strategy for cognitive impairment and dementia, especially in hypertensive patients with the APOE ε4 allele.

Clinical Trial Registration:www.ClinicalTrials.gov, ChiCTR.org.cn, identifier ChiCTR-IOR-17013557. Registered on April 12, 2017 – Retrospectively registered, http://www.chictr.org.cn/showproj.aspx?proj=23121

The anxiolytic effects of atorvastatin and simvastatin on dietary-induced increase in homocysteine levels in rats

The aim of this study was to evaluate the effects of atorvastatin and simvastatin on behavioral manifestations that followed hyperhomocysteinemia induced by special dietary protocols enriched in methionine and deficient in B vitamins (B6, B9, B12) by means of alterations in anxiety levels in rats. Simultaneously, we investigated the alterations of oxidative stress markers in rat hippocampus induced by applied dietary protocols. Furthermore, considering the well-known antioxidant properties of statins, we attempted to assess their impact on major markers of oxidative stress and their possible beneficial role on anxiety-like behavior effect in rats. The 4-week-old male Wistar albino rats were divided (eight per group) according to basic dietary protocols: standard chow, methionine-enriched, and methionine-enriched vitamins B (B6, B9, B12) deficient. Each dietary protocol (30 days) included groups with atorvastatin (3 mg/kg/day i.p.) and simvastatin (5 mg/kg/day i.p.). The behavioral testing was performed in the open field and elevated plus maze tests. Parameters of oxidative stress (index of lipid peroxidation, superoxide dismutase, catalase activity, glutathione) were determined in hippocampal tissue samples following decapitation after anesthesia. Methionine-load dietary protocols induced increased oxidative stress in rat hippocampus, which was accompanied by anxiogenic behavioral manifestations. The methionine-enriched diet with restricted vitamins B intake induced more pronounced anxiogenic effect, as well as increased oxidative stress compared to the methionine-load diet with normal vitamins B content. Simultaneous administration of statins showed beneficial effects by means of both decreased parameters of oxidative stress and attenuation of anxiety. The results obtained with simvastatin were more convincible compared to atorvastatin.