Clopidogrel Administration Impairs Post-Stroke Learning and Memory Recovery in Mice

Icaritin Promotes Brain Functional Rehabilitation in Ischemic Stroke Rats by Regulating Astrocyte Activation and Polarization Via GPER

BACKGROUND

Cerebral ischemic injury induces the polarization of astrocytes toward two different phenotypes, i.e., the proinflammatory A1 phenotype and the protective, anti-inflammatory A2 phenotype, affects the prognosis of cerebral ischemia. To explore the neuroprotective effect of phytoestrogens ICT on cerebral ischemic rehabilitation and the preliminary mechanism of regulating astrocyte polarization.

METHODS

Transient middle cerebral artery occlusion (tMCAO)/reperfusion was performed on rats and then treated with ICT (i.p.) once daily for 28 days. Intervention of GPER specific inhibitor G15 was repeated. The body weight, Garcia JH scale, right/left brain weight ratio, CatWalk gait test and Y maze test to assess overall neural function in rats. Cytokines in ischemic cortical were detected by ELISA. The number of newborn neurons was observed by BrdU staining, and the double immunofluorescence staining and Western blotting to evaluated the activation and A1 and A2 polarization of astrocytes.

RESULTS

The results showed that ICT treatment markedly perfected functional outcomes on a long-term basis after ischemic stroke, it also improved learning and memory and gait. ICT inhibited the polarization of A1 type astrocytes and promoted the polarization of A2 type astrocytes, promote neuron regeneration in hippocampus DG region. G15 removes some of the protective effects of ICT.

CONCLUSIONS

The experimental results show that ICT exerts neuroprotective effects and regulates astrocyte polarization through GPER, suggesting that it may be a potential therapeutic agent for ischemic stroke during the recovery period.

Highly prevalent geriatric medications and their effect on β-amyloid fibril formation

BACKGROUND

The unprecedented increase in the older population and ever-increasing incidence of dementia are leading to a "silver tsunami" in upcoming decades. To combat multimorbidity and maintain daily activities, elderly people face a high prevalence of polypharmacy. However, how these medications affect dementia-related pathology, such as Alzheimer's β-amyloid (Aβ) fibrils formation, remains unknown. In the present study, we aimed to analyze the medication profiles of Alzheimer's disease (AD; n = 124), mild cognitive impairment (MCI; n = 114), and non-demented (ND; n = 228) patients to identify highly prevalent drugs and to determine the effects of those drugs on Aβ fibrils formation.

METHODS

Study subjects (≥ 65 years) were recruited from an academic geriatric practice that heavily focuses on memory disorders. The disease state was defined based on the score of multiple cognitive assessments. Individual medications for each subject were listed and categorized into 10 major drug classes. Statistical analysis was performed to determine the frequency of individual and collective drug classes, which are expressed as percentages of the respective cohorts. 10 µM monomeric β-amyloid (Aβ) 42 and fibrillar Aβ (fAβ) were incubated for 6-48 h in the presence of 25 µM drugs. fAβ was prepared with a 1:10 ratio of Aβ42 to Aβ40. The amount of Aβ fibrils was monitored using a thioflavin T (Th-T) assay. Neuronal cells (N2A and SHSY-5Y) were treated with 25 µM drugs, and cell death was measured using a lactose dehydrogenase (LDH) assay.

RESULTS

We noticed a high prevalence (82-90%) of polypharmacy and diverse medication profiles including anti-inflammatory (65-77%), vitamin and mineral (64-72%), anti-cholesterol (33-41%), anti-hypersensitive (35-39%), proton pump inhibitor (23-34%), anti-thyroid (9-21%), anti-diabetic (5-13%), anti-constipation (9-11%), anti-coagulant (10-13%), and anti-insomnia (9-20%) drugs in the three cohorts. Our LDH assay with 18 highly prevalent drug components showed toxic effects of Norvasc, Tylenol, Colace, and Plavix on N2A cells, and of vitamin D and Novasc on SH-SY5Y cells. All these drugs except Colace significantly reduced the amount of Aβ fibril when incubated with Aβ42 for a short period (6 h). However, Lipitor, vitamin D, Levothyroxine, Prilosec, Flomax, and Norvasc prominently reduce the amount of fibrils when incubated with monomeric Aβ42 for a longer period (48 h). Furthermore, our disaggregation study with fAβ showed consistent results for cholecalciferol (vitamin D), omeprazole (Prilosec), clopidogrel hydrogensulfate (Flomax), levothyroxine, and amlodipine (Norvasc). The chemical structures of these four efficient molecules contain polyphenol components, a characteristic feature of the structures of polyphenolic inhibitors of Aβ fibrillation.

CONCLUSION

A higher polypharmacy incidence was observed in an elderly population of 228 ND, 114 MCI, and 124 AD patients. We found that several highly recommended drug components, including vitamin D3, Levothyroxine, Prilosec, Flomax, and Norvasc, efficiently reduce the amount of fibrils formed by monomeric Aβ42 and existing preformed Aβ fibrils in vitro. However, only Levothyroxine was able to prevent Aβ-mediated toxicity to SH-SY5Y cells. Our study suggested that these drugs likely function as polyphenolic inhibitors of Aβ.

Update on the mechanism of microglia involvement in post-stroke cognitive impairment

Post-stroke cognitive impairment (PSCI) is a clinical syndrome characterized by cognitive deficits that manifest following a stroke and persist for up to 6 months post-event. This condition is grave, severely compromising patient quality of life and longevity, while also imposing substantial economic burdens on societies worldwide. Despite significant advancements in identifying risk factors for PSCI, research into its underlying mechanisms and therapeutic interventions remains inadequate. Microglia, the brain's primary immune effector cells, are pivotal in maintaining, nurturing, defending, and repairing neuronal function, a process intrinsically linked to PSCI's progression. Thus, investigating microglial activation and mechanisms in PSCI is crucial. This paper aims to foster new preventive and therapeutic approaches for PSCI by elucidating the roles, mechanisms, and characteristics of microglia in the condition.

Role of microglia in stroke

Microglia play key roles in the post-ischemic inflammatory response and damaged tissue removal reacting rapidly to the disturbances caused by ischemia and working to restore the lost homeostasis. However, the modified environment, encompassing ionic imbalances, disruption of crucial neuron-microglia interactions, spreading depolarization, and generation of danger signals from necrotic neurons, induce morphological and phenotypic shifts in microglia. This leads them to adopt a proinflammatory profile and heighten their phagocytic activity. From day three post-ischemia, macrophages infiltrate the necrotic core while microglia amass at the periphery. Further, inflammation prompts a metabolic shift favoring glycolysis, the pentose-phosphate shunt, and lipid synthesis. These shifts, combined with phagocytic lipid intake, drive lipid droplet biogenesis, fuel anabolism, and enable microglia proliferation. Proliferating microglia release trophic factors contributing to protection and repair. However, some microglia accumulate lipids persistently and transform into dysfunctional and potentially harmful foam cells. Studies also showed microglia that either display impaired apoptotic cell clearance, or eliminate synapses, viable neurons, or endothelial cells. Yet, it will be essential to elucidate the viability of engulfed cells, the features of the local environment, the extent of tissue damage, and the temporal sequence. Ischemia provides a rich variety of region- and injury-dependent stimuli for microglia, evolving with time and generating distinct microglia phenotypes including those exhibiting proinflammatory or dysfunctional traits and others showing pro-repair features. Accurate profiling of microglia phenotypes, alongside with a more precise understanding of the associated post-ischemic tissue conditions, is a necessary step to serve as the potential foundation for focused interventions in human stroke.

Melatonin Ameliorates Post-Stroke Cognitive Impairment in Mice by Inhibiting Excessive Mitophagy

Post-stroke cognitive impairment (PSCI) remains the most common consequence of ischemic stroke. In this study, we aimed to investigate the role and mechanisms of melatonin (MT) in improving cognitive dysfunction in stroke mice. We used CoCl2-induced hypoxia-injured SH-SY5Y cells as a cellular model of stroke and photothrombotic-induced ischemic stroke mice as an animal model. We found that the stroke-induced upregulation of mitophagy, apoptosis, and neuronal synaptic plasticity was impaired both in vivo and in vitro. The results of the novel object recognition test and Y-maze showed significant cognitive deficits in the stroke mice, and Nissl staining showed a loss of neurons in the stroke mice. In contrast, MT inhibited excessive mitophagy both in vivo and in vitro and decreased the levels of mitophagy proteins PINK1 and Parkin, and immunofluorescence staining showed reduced co-localization of Tom20 and LC3. A significant inhibition of mitophagy levels could be directly observed under transmission electron microscopy. Furthermore, behavioral experiments and Nissl staining showed that MT ameliorated cognitive deficits and reduced neuronal loss in mice following a stroke. Our results demonstrated that MT inhibits excessive mitophagy and improves PSCI. These findings highlight the potential of MT as a preventive drug for PSCI, offering promising therapeutic implications.