MicroRNA modulation is a potential molecular mechanism for neuroprotective effects of intranasal insulin administration in amyloid βeta oligomer induced Alzheimer's like rat model

Intranasal insulin treatment ameliorates spatial memory, muscular strength, and frailty deficits in 5xFAD mice

The 5xFAD mouse model shows age-related weight loss as well as cognitive and motor deficits. Metabolic dysregulation, especially impaired insulin signaling, is also present in AD. This study examined whether intranasal delivery of insulin (INI) at low (0.875 U) or high (1.750 U) doses would ameliorate these deficits compared to saline in 10-month-old female 5xFAD and B6SJL wildtype (WT) mice. INI increased forelimb grip strength in the wire hang test in 5xFAD mice in a dose-dependent manner but did not improve the performance of 5xFAD mice on the balance beam. High INI doses reduced frailty scores in 5xFAD mice and improved spatial memory in both acquisition and reversal probe trials in the Morris water maze. INI increased swim speed in 5xFAD mice but had no effect on object recognition memory or working memory in the spontaneous alternation task, nor did it improve memory in the contextual or cued fear memory tasks. High doses of insulin increased the liver, spleen, and kidney weights and reduced brown adipose tissue weights. P-Akt signaling in the hippocampus was increased by insulin in a dose-dependent manner. Altogether, INI increased strength, reduced frailty scores, and improved visual spatial memory. Hypoglycemia was not present after INI, however alterations in tissue and organ weights were present. These results are novel and important as they indicate that intra-nasal insulin can reverse cognitive, motor and frailty deficits found in this mouse model of AD.

miR-30a-5p mediates ferroptosis of hippocampal neurons in chronic cerebral hypoperfusion-induced cognitive dysfunction by modulating the SIRT1/NRF2 pathway

OBJECTIVE

Chronic cerebral hypoperfusion (CCH) is a common cause of brain dysfunction. As a microRNA (also known as miRNAs or miRs), miR-30a-5p participates in neuronal damage and relates to ferroptosis. We explored the in vivo and in vitro effects and functional mechanism of miR-30a-5p in CCH-triggered cognitive impairment through the silent information regulator 1 (SIRT1)/nuclear factor erythroid 2-related factor 2 (NRF2) pathway.

METHODS

After 1 month of CCH modeling through bilateral common carotid artery stenosis, mice were injected with 2 μL antagomir (also known as anti-miRNAs) miR-30a-5p, with cognitive function evaluated by Morris water maze and novel object recognition tests. In vitro HT-22 cell oxygen glucose deprivation (OGD) model was established, followed by miR-30a-5p inhibitor and/or si-SIRT1 transfections, with Fe2+ concentration, malonaldehyde (MDA) and glutathione (GSH) contents, reactive oxygen species (ROS), miR-30a-5p and SIRT1 and glutathione peroxidase 4 (GPX4) protein levels, NRF2 nuclear translocation, and miR-30a-5p-SIRT1 targeting relationship assessed.

RESULTS

CCH-induced mice showed obvious cognitive impairment, up-regulated miR-30a-5p, and down-regulated SIRT1. Ferroptosis occurred in hippocampal neurons, manifested by elevated Fe2+ concentration and ROS and MDA levels, mitochondrial atrophy, and diminished GSH content. Antagomir miR-30a-5p or miR-30a-5p inhibitor promoted SIRT1 expression and NRF2 nuclear translocation, increased GPX4, cell viability and GSH content, and reduced Fe2+ concentration and ROS and MDA levels. miR-30a-5p negatively regulated SIRT1. In vitro, miR-30a-5p knockout increased NRF2 nuclear translocation by up-regulating SIRT1, inhibiting OGD-induced ferroptosis in HT-22 cells.

CONCLUSION

miR-30a-5p induces hippocampal neuronal ferroptosis and exacerbates post-CCH cognitive dysfunction by targeting SIRT1 and reducing NRF2 nuclear translocation.

Cacao consumption improves passive avoidance memory impairment in a rat model of Alzheimer's disease: the role of hippocampal synaptic plasticity and oxidative stress

Introduction: Alzheimer's disease (AD) causes progressive loss of cognitive function and synaptic plasticity, which is the most common form of dementia. The present study was designed to scrutinize the effects of cacao on passive avoidance memory function and to identify the roles of hippocampal synaptic plasticity and oxidative stress in an AD rat model induced by unilateral intracerebroventricular (UICV) injection of amyloid-beta (Aβ). Methods: Oral administration of cacao (500 mg/kg/ day) was given for 2 consecutive months. A memory retention test was conducted 24 h after passive avoidance training was completed. Subsequently, the amplitude of population spike (PS) and slope of field excitatory postsynaptic potentials (fEPSPs) were assessed at hippocampal long-term potentiation (LTP) in perforant pathway-dentate gyrus (PP-DG) synapses. Moreover, total thiol group (TTG) and malondialdehyde (MDA) concentrations were evaluated in the plasma. Furthermore, compact Aβ plaques were detected in the hippocampal DG by performing Congo red staining. Results: As a result of AD induction, passive avoidance memory was impaired; also, reduced fEPSP slopes, PS amplitudes, and content of TTG, and increase in MDA levels in the rats were observed. In contrast, cacao treatment ameliorated passive avoidance memory impairment, improved hippocampal LTP impairment, modulated oxidative-antioxidative status, and delayed Aβ plaques production in AD rats. Disscussion: Conclusively, cacao alleviates Aβ-induced cognitive deficit, probably by the amelioration of hippocampal LTP impairment, modulation of oxidative-antioxidative status, and inhibition of Aβ plaque accumulation.

Mesenchymal Stem Cells from Familial Alzheimer's Patients Express MicroRNA Differently

Alzheimer's disease (AD) is a progressive neurodegenerative disorder and the predominant form of dementia globally. No reliable diagnostic, predictive techniques, or curative interventions are available. MicroRNAs (miRNAs) are vital to controlling gene expression, making them valuable biomarkers for diagnosis and prognosis. This study examines the transcriptome of olfactory ecto-mesenchymal stem cells (MSCs) derived from individuals with the PSEN1(A431E) mutation (Jalisco mutation). The aim is to determine whether this mutation affects the transcriptome and expression profile of miRNAs and their target genes at different stages of asymptomatic, presymptomatic, and symptomatic conditions. Expression microarrays compare the MSCs from mutation carriers with those from healthy donors. The results indicate a distinct variation in the expression of miRNAs and mRNAs among different symptomatologic groups and between individuals with the mutation. Using bioinformatics tools allows us to identify target genes for miRNAs, which in turn affect various biological processes and pathways. These include the cell cycle, senescence, transcription, and pathways involved in regulating the pluripotency of stem cells. These processes are closely linked to inter- and intracellular communication, vital for cellular functioning. These findings can enhance our comprehension and monitoring of the disease's physiological processes, identify new disorder indicators, and develop innovative treatments and diagnostic tools for preventing or treating AD.

Protective effects of Zishen Huoxue recipe against neuronal injury in the neurovascular unit of rats with vascular dementia by interfering with inflammatory cascade-induced pyroptosis

OBJECTIVE

Chinese herbal formulas show considerable therapeutic benefits in dementia. This study specifically explored the protective action of Zishen Huoxue recipe on the neurovascular unit (NVU) of rats with vascular dementia (VD).

METHODS

VD rat models were established by permanent bilateral common carotid artery occlusion and treated with Zishen Huoxue recipe. In vitro glucose‑oxygen deprivation (OGD)-injured NVU models were established and treated with miR-124-3p agomir or rat medicated serum. The neurological damage, histopathological changes, and neuronal injury in the rat hippocampus were assessed using Morris water maze test and histological stainings. Expression of miR-124-3p was determined using RT-qPCR. The blood-brain barrier/NVU injury, cell pyroptosis, NLRP3 inflammasome activation, and release of inflammatory factors were analyzed mainly by immunofluorescence analysis, TUNEL staining, Western blot, and ELISA. QS-21 (an NLRP3 activator) was used to verify the role of miR-124-3p/NLRP3.

RESULTS

Zishen Huoxue recipe ameliorated the learning/memory deficits, neuronal injury, NVU insults, cell pyroptosis, activation of NLRP3 inflammasome, and extensive secretion of lactate dehydrogenase/IL-1β/IL-18 in VD rats. miR-124-3p was downregulated in VD rats but upregulated after treatment of this recipe. miR-124-3p overexpression ameliorated NVU insults, reduced cell pyroptosis, lowered NLRP3 inflammasome activation, and suppressed inflammatory responses in OGD-injured NVU models. NLRP3 inflammasome activation partly counteracted the amelioration effect of miR-124-3p on pyroptosis. Zishen Huoxue recipe could upregulate miR-124-3p to suppress pyroptosis and protect NVU function.

CONCLUSION

Zishen Huoxue recipe can upregulate miR-124-3p expression to repress the inflammatory cascade-evoked pyroptosis, thereby protecting against neuronal injury in the NVU of VD rats.

Repositioning of Anti-Diabetic Drugs against Dementia: Insight from Molecular Perspectives to Clinical Trials

Insulin resistance as a hallmark of type 2 DM (T2DM) plays a role in dementia by promoting pathological lesions or enhancing the vulnerability of the brain. Numerous studies related to insulin/insulin-like growth factor 1 (IGF-1) signaling are linked with various types of dementia. Brain insulin resistance in dementia is linked to disturbances in Aβ production and clearance, Tau hyperphosphorylation, microglial activation causing increased neuroinflammation, and the breakdown of tight junctions in the blood-brain barrier (BBB). These mechanisms have been studied primarily in Alzheimer's disease (AD), but research on other forms of dementia like vascular dementia (VaD), Lewy body dementia (LBD), and frontotemporal dementia (FTD) has also explored overlapping mechanisms. Researchers are currently trying to repurpose anti-diabetic drugs to treat dementia, which are dominated by insulin sensitizers and insulin substrates. Although it seems promising and feasible, none of the trials have succeeded in ameliorating cognitive decline in late-onset dementia. We highlight the possibility of repositioning anti-diabetic drugs as a strategy for dementia therapy by reflecting on current and previous clinical trials. We also describe the molecular perspectives of various types of dementia through the insulin/IGF-1 signaling pathway.

Energy Crisis Links to Autophagy and Ferroptosis in Alzheimer's Disease: Current Evidence and Future Avenues

Alzheimer's disease (AD) is one of the most common neurodegenerative diseases worldwide. The occult nature of the onset and the uncertainty of the etiology largely impede the development of therapeutic strategies for AD. Previous studies revealed that the disorder of energy metabolism in the brains of AD patients appears far earlier than the typical pathological features of AD, suggesting a tight association between energy crisis and the onset of AD. Energy crisis in the brain is known to be induced by the reductions in glucose uptake and utilization, which may be ascribed to the diminished expressions of cerebral glucose transporters (GLUTs), insulin resistance, mitochondrial dysfunctions, and lactate dysmetabolism. Notably, the energy sensors such as peroxisome proliferators-activated receptor (PPAR), transcription factor EB (TFEB), and AMP-activated protein kinase (AMPK) were shown to be the critical regulators of autophagy, which play important roles in regulating beta-amyloid (Aβ) metabolism, tau phosphorylation, neuroinflammation, iron dynamics, as well as ferroptosis. In this study, we summarized the current knowledge on the molecular mechanisms involved in the energy dysmetabolism of AD and discussed the interplays existing between energy crisis, autophagy, and ferroptosis. In addition, we highlighted the potential network in which autophagy may serve as a bridge between energy crisis and ferroptosis in the progression of AD. A deeper understanding of the relationship between energy dysmetabolism and AD may provide new insight into developing strategies for treating AD; meanwhile, the energy crisis in the progression of AD should gain more attention.

The effects of resistance training and spirulina on the performance of the antioxidant system with emphasis on mir125b, mir146a and cognitive function in stanazolol-induced neurotoxicity in rats

Abuse of anabolic-androgenic steroids (AAS) is associated with neurological and cognitive problems in athletes. The Purpose of this study was to investigate the simultaneous effect of resistance training (RT) and spirulina supplementation (Sp) on the function of the antioxidant system with emphasis on mir125b, mir146a and cognitive function in Stanazolol (S)-induced neurotoxicity in rats. This experimental animal model study was performed with a post-test design with a control group. 45 male Sprague-Dawley rats were divided into six groups of 9 animals including (Althobaiti et al., 2022) [1]: sham (Sh/normal saline intake) (Havnes et al., 2019) [2], 25 mg/kg/wk of stanazolol (S) (Albano et al., 2021) [3], S + 100 mg/kg of Sp + (S + Sp) (Bjørnebekk et al., 2021) [4], RT (six weeks with an intensity of 50-100% of body weight) + S (S + RT) (Kanayama et al., 2013) [5] S + Sp + RT. Levels of superoxide dismutase (SOD), glutathione peroxidase (GPx), total antioxidant capacity (TAC), malondialdehyde (MDA), percentage of healthy cells in the C1 and C3 regions of hippocampus, miR125b, miR146a, step-through latency (STL), time spent in dark compartment (TDC), repeated entry in dark compartment (RDC) and percentage of alternation (PA%) were measured in the post-test. Results showed that the Sp, RT and SP + RT increased levels of SOD, GPx and percentage of healthy cells in C1 region, decreased MDA, mir125b, mir146a in hippocampal tissue and decreased TDC levels in S-exposed rats (P ≤ 0.05). Sp + RT decreased RDC and increased SOD levels; on the other hand, RT decreased RDC levels in S-exposed rats (P ≤ 0.05). Levels of TAC in the Sp groups were significantly higher than the S group (P ≤ 0.05). Also, the effect of Sp + RT in reducing miR125b, miR146a, and STL levels was much higher than the effect of Sp and RT alone (P ≤ 0.05). It seems that applying resistance training and spirulina supplementation both separately and interactively is effective in improving the antioxidant system as well as memory and learning in cognitive impairment caused by stanazolol. However, more studies on microRNAs are needed.

MicroRNA-22-3p ameliorates Alzheimer's disease by targeting SOX9 through the NF-κB signaling pathway in the hippocampus

Background

Studies have suggested that many down-regulated miRNAs identified in the brain tissue or serum of Alzheimer’s disease (AD) patients were involved in the formation of senile plaques and neurofibrillary tangles. Specifically, our previous study revealed that microRNA-22-3p (miR-22-3p) was significantly down-regulated in AD patients. However, the molecular mechanism underlying the down-regulation of miR-22-3p has not been comprehensively investigated.

Methods

The ameliorating effect of miR-22-3p on apoptosis of the Aβ-treated HT22 cells was detected by TUNEL staining, flow cytometry, and western blotting. The cognition of mice with stereotaxic injection of agomir or antagomir of miR-22-3p was assessed by Morris water maze test. Pathological changes in the mouse hippocampus were analyzed using hematoxylin and eosin (HE) staining, Nissl staining, and immunohistochemistry. Proteomics analysis was performed to identify the targets of miR-22-3p, which were further validated using dual-luciferase reporter analysis and western blotting analysis.

Results

The miR-22-3p played an important role in ameliorating apoptosis in the Aβ-treated HT22 cells. Increased levels of miR-22-3p in the mouse hippocampus improved the cognition in mice. Although the miR-22-3p did not cause the decrease of neuronal loss in the hippocampus, it reduced the Aβ deposition. Proteomics analysis revealed Sox9 protein as the target of miR-22-3p, which was verified by the luciferase reporter experiments.

Conclusion

Our study showed that miR-22-3p could improve apoptosis and reduce Aβ deposition by acting on Sox9 through the NF-κB signaling pathway to improve the cognition in AD mice. We concluded that miR-22-3p ameliorated AD by targeting Sox9 through the NF-κB signaling pathway in the hippocampus.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12974-022-02548-1.