Akt / GSK3β / Nrf2 / HO-1 pathway activation by flurbiprofen protects the hippocampal neurons in a rat model of glutamate excitotoxicity

Platycodin D Ameliorates Cognitive Impairment in Type 2 Diabetes Mellitus Mice via Regulating PI3K/Akt/GSK3β Signaling Pathway

Objectives: The aim of this study was to investigate the ameliorative effect of platycodin D (PD) on cognitive dysfunction in type 2 diabetes mellitus (T2DM) and its potential molecular mechanisms of action in vivo and in vitro. Materials and methods: An animal model of cognitive impairment in T2DM was established using a single intraperitoneal injection of streptozotocin (100 mg/kg) after 8 weeks of feeding a high-fat diet to C57BL/6 mice. In vitro, immunofluorescence staining and Western blot were employed to analyze the effects of PD on glucose-induced neurotoxicity in mouse hippocampal neuronal cells (HT22). Results: PD (2.5 mg/kg) treatment for 4 weeks significantly suppressed the rise in fasting blood glucose in T2DM mice, improved insulin secretion deficiency, and reversed abnormalities in serum triglyceride, cholesterol, low-density lipoprotein, and high-density lipoprotein levels. Meanwhile, PD ameliorated choline dysfunction in T2DM mice and inhibited the production of oxidative stress and apoptosis-related proteins of the caspase family. Notably, PD dose-dependently prevents the loss of mitochondrial membrane potential, promotes phosphorylation of phosphatidylinositol 3 kinase and protein kinase B (Akt) in vitro, activates glycogen synthase kinase 3β (GSK3β) expression at the Ser9 site, and inhibits Tau protein hyperphosphorylation. Conclusions: These findings clearly indicated that PD could alleviate the neurological damage caused by T2DM, and the phosphorylation of Akt at Ser473 may be the key to its effect.

The Role of NRF2 in Trinucleotide Repeat Expansion Disorders

Trinucleotide repeat expansion disorders, a diverse group of neurodegenerative diseases, are caused by abnormal expansions within specific genes. These expansions trigger a cascade of cellular damage, including protein aggregation and abnormal RNA binding. A key contributor to this damage is oxidative stress, an imbalance of reactive oxygen species that harms cellular components. This review explores the interplay between oxidative stress and the NRF2 pathway in these disorders. NRF2 acts as the master regulator of the cellular antioxidant response, orchestrating the expression of enzymes that combat oxidative stress. Trinucleotide repeat expansion disorders often exhibit impaired NRF2 signaling, resulting in inadequate responses to excessive ROS production. NRF2 activation has been shown to upregulate antioxidative gene expression, effectively alleviating oxidative stress damage. NRF2 activators, such as omaveloxolone, vatiquinone, curcumin, sulforaphane, dimethyl fumarate, and resveratrol, demonstrate neuroprotective effects by reducing oxidative stress in experimental cell and animal models of these diseases. However, translating these findings into successful clinical applications requires further research. In this article, we review the literature supporting the role of NRF2 in the pathogenesis of these diseases and the potential therapeutics of NRF2 activators.

Is aromatic plants environmental health engineering (APEHE) a leverage point of the earth system?

It is important to note that every ecological niche in an ecosystem is significant. This study aims to assess the importance of medicinal and aromatic plants (MAPs) in the ecosystem from multiple perspectives. A primary model of Aromatic Plants Environmental Health Engineering (APEHE) has been designed and constructed. The APEHE system was used to collect aerosol compounds, and it was experimentally verified that these compounds have the potential to impact human health by binding to AKT1 as the primary target, and MMP9 and TLR4 as secondary targets. These compounds may indirectly affect human immunity by reversing drug resistance in drug-resistant bacteria in the nasal cavity. This is mainly achieved through combined mutations in sdhA, scrA, and PEP. Our findings are based on Network pharmacology and molecular binding, drug-resistance rescue experiments, as well as combined transcriptomics and metabolomics experiments. It is suggested that APEHE may have direct or indirect effects on human health. We demonstrate APEHE's numerous potential benefits, such as attenuation and elimination of airborne microorganisms in the environment, enhancing carbon and nitrogen storage in terrestrial ecosystems, promoting the formation of low-level clouds and strengthening the virtuous cycle of Earth's ecosystems. APEHE also supports the development of transdisciplinary technologies, including terpene energy production. It facilitates the creation of a sustainable circular economy and provides additional economic advantages through urban optimisation, as well as fresh insights into areas such as the habitability of other planets. APEHE has the potential to serve as a leverage point for the Earth system. We have created a new research direction.

Human dental pulp stem cells mitigate the neuropathology and cognitive decline via AKT-GSK3β-Nrf2 pathways in Alzheimer's disease

Oxidative stress is increasingly recognized as a major contributor to the pathophysiology of Alzheimer's disease (AD), particularly in the early stages of the disease. The multiplicity advantages of stem cell transplantation make it fascinating therapeutic strategy for many neurodegenerative diseases. We herein demonstrated that human dental pulp stem cells (hDPSCs) mediated oxidative stress improvement and neuroreparative effects in in vitro AD models, playing critical roles in regulating the polarization of hyperreactive microglia cells and the recovery of damaged neurons. Importantly, these therapeutic effects were reflected in 10-month-old 3xTg-AD mice after a single transplantation of hDPSCs, with the treated mice showing significant improvement in cognitive function and neuropathological features. Mechanistically, antioxidant and neuroprotective effects, as well as cognitive enhancements elicited by hDPSCs, were at least partially mediated by Nrf2 nuclear accumulation and downstream antioxidant enzymes expression through the activation of the AKT-GSK3β-Nrf2 signaling pathway. In conclusion, our findings corroborated the neuroprotective capacity of hDPSCs to reshape the neuropathological microenvironment in both in vitro and in vivo AD models, which may be a tremendous potential therapeutic candidate for Alzheimer's disease.

Nrf-2-dependent antioxidant and anti-inflammatory effects underlie the protective effect of esculeoside A against retinal damage in streptozotocin-induced diabetic rats

Esculeoside A (ESA) is a tomato-derived glycoside with antioxidant and anti-inflammatory properties. The protective effect of ESA against diabetic retinopathy is not well-investigated and was the core objective of this study. In addition, we tested if such protection involves the activation of Nrf2 signaling. Type 1 diabetes mellitus (T1DM) was induced in adult Wistar male rats by an intraperitoneal injection of streptozotocin (65 mg/kg). Non-diabetic and T1DM rats were divided into two subgroup groups given either the vehicle or ESA (100 mg)/kg. An additional T1DM group was given ESA (100 mg/kg) and an Nrf2 inhibitor (2 mg/kg) (n=8 rats/group). Treatments continued for 12 weeks. In this study, according to the histological features, ESA improved the structure of ganglionic cells and increased the number of cells of the inner nuclear and plexiform layers in the retinas of T1DM rats. Concomitantly, it reduced the retina levels of malondialdehyde (lipid peroxides), vascular endothelial growth factor, interleukin-6, tumor necrosis factor-α, Bax, and caspase-3. In the retinas of the control and diabetic rats, ESA boosted the levels of total glutathione, superoxide dismutase, heme-oxygenase-1, and Bcl2, reduced the mRNA levels of REDD1, and enhanced cytoplasmic and nuclear levels of Nrf2. However, ESA failed to alter the mRNA levels of Nrf2 and keap1, protein levels of keap1, plasma glucose, plasma insulin, serum triglycerides, cholesterol, and LDL-c in both the control and T1DM rats. In conclusion, ESA alleviates retinopathy in T1DM rats by suppressing REDD1-associated degradation and inhibiting the Nrf2/antioxidant axis.

Correlations between the structure and anti-diabetic activity of novel polysaccharides from raw and "Nine Steaming Nine Sun-Drying" Polygonti rhizome

"Nine Steaming Nine Sun-Drying" Polygonti rhizome has been used as valuable tonic health-care products for thousands of years. This research aimed to determine the correlations between the structure and anti-diabetic activities of three novel polysaccharides isolated from the raw and "Nine Steaming Nine Sun-Drying" Polygonti rhizome, with PRP-R from the raw ones and PRP-9Z and PRP-9A from the steamed ones. Structures of the isolated polysaccharides were determined by IR and NMR spectra, as well as monosaccharide composition and methylation analysis. In vitro assays indicated that PRP-9Z could improve the glucose consumptions more effectively than PRP-R and PRP-9A via Akt/GSK3β insulin signal pathway by western blotting analysis. In vivo assays indicated PRP-9Z could improve the glucose tolerance in the BKS-db mice. Histopathological assay demonstrated that PRP-9Z effectively reduced the damage of the kidney and liver. The above results indicated that PRP-9Z from "Nine Steaming Nine Sun-Drying" Polygonti rhizome showed significant anti-diabetic properties, which indicated that PRP-9Z with higher content of →1)-β-Frup-(2→ was more active than PRP-R with higher →1,6)-β-Fruf-(2→ and PRP-9A with higher →4)-β-Galp(1→.

The cell-specific roles of Nrf2 in acute and chronic phases of ischemic stroke

Ischemic stroke refers to the sudden loss of blood flow in a specific area of the brain. It is the fifth leading cause of mortality and the leading cause of permanent disability. The transcription factor nuclear factor erythroid 2-related factor 2 (Nrf2) controls the production of several antioxidants and protective proteins and it has been investigated as a possible pharmaceutical target for reducing harmful oxidative events in brain ischemia. Each cell type exhibits different roles and behaviors in different phases post-stroke, which is comprehensive yet important to understand to optimize management strategies and goals for care for stroke patients. In this review, we comprehensively summarize the protective effects of Nrf2 in experimental ischemic stroke, emphasizing the role of Nrf2 in different cell types including neurons, astrocytes, oligodendrocytes, microglia, and endothelial cells during acute and chronic phases of stroke and providing insights on the neuroprotective role of Nrf2 on each cell type throughout the long term of stroke care. We also highlight the importance of targeting Nrf2 in clinical settings while considering a variety of important factors such as age, drug dosage, delivery route, and time of administration.

Synergistic neuroprotection by phytocompounds of Bacopa monnieri in scopolamine-induced Alzheimer's disease mice model

BACKGROUND

Millions of people around the globe are affected by Alzheimer's disease (AD). This crippling condition has no treatment despite intensive studies. Some phytocompounds have been shown to protect against Alzheimer's in recent studies.

METHODS

Thus, this work aimed to examine Bacopa monnieri phytocompounds' synergistic effects on neurodegeneration, antioxidant activity, and cognition in the scopolamine-induced AD mice model. The toxicity study of two phytocompounds: quercetin and bacopaside X revealed an LD50 of more than 2000 mg/kg since no deaths occurred.

RESULTS

The neuroprotection experiment consists of 6 groups i.e., control (saline), scopolamine (1 mg/kg), donepezil (5 mg/kg), Q (25 mg/kg), BX (20 mg/kg), and Q + BX (25 mg/kg + 20 mg/kg). Visual behavioral assessment using the Morris water maze showed that animals in the diseased model group (scopolamine) moved more slowly toward the platform and exhibited greater thigmotaxis behavior than the treatment and control groups. Likewise, the concentration of biochemical NO, GSH, and MDA improved in treatment groups concerning the diseased group. mRNA levels of different marker genes including ChAT, IL-1α, IL-1 β, TNF α, tau, and β secretase (BACE1) improved in treatment groups with respect to the disease group.

CONCLUSION

Both bacopaside X and quercetin synergistically have shown promising results in neuroprotection. Therefore, it is suggested that Q and BX may work synergistically due to their antioxidant and neuroprotective property.

Insights into the role of PHLPP2/Akt/GSK3β/Fyn kinase/Nrf2 trajectory in the reno-protective effect of rosuvastatin against colistin-induced acute kidney injury in rats

OBJECTIVES

Oxidative stress-mediated colistin's nephrotoxicity is associated with the diminished activity of nuclear factor erythroid 2-related factor 2 (Nrf2) that is primarily correlated with cellular PH domain and leucine-rich repeat protein phosphatase (PHLPP2) levels. This study investigated the possible modulation of PHLPP2/protein kinase B (Akt) trajectory as a critical regulator of Nrf2 stability by rosuvastatin (RST) to guard against colistin-induced oxidative renal damage in rats.

METHODS

Colistin (300,000 IU/kg/day; i.p.) was injected for 6 consecutive days, and rats were treated simultaneously with RST orally at 10 or 20 mg/kg.

KEY FINDINGS

RST enhanced renal nuclear Nrf2 translocation as revealed by immunohistochemical staining to boost the renal antioxidants, superoxide dismutase (SOD) and reduced glutathione (GSH) along with a marked reduction in caspase-3. Accordingly, rats treated with RST showed significant restoration of normal renal function and histological features. On the molecular level, RST effectively decreased the mRNA expression of PHLPP2 to promote Akt phosphorylation. Consequently, it deactivated GSK-3β and reduced the gene expression of Fyn kinase in renal tissues.

CONCLUSIONS

RST could attenuate colistin-induced oxidative acute kidney injury via its suppressive effect on PHLPP2 to endorse Nrf2 activity through modulating Akt/GSK3 β/Fyn kinase trajectory.

Celastrol confers ferroptosis resistance via AKT/GSK3β signaling in high-fat diet-induced cardiac injury

Obesity-induced cardiac dysfunction is a severe global disease associated with high dietary fat intake, and its pathogenesis includes inflammation, oxidative stress, and ferroptosis. Celastrol (Cel) is a bioactive compound isolated from the herb Tripterygium wilfordii, which has a protective influence on cardiovascular diseases. In this study, the role of Cel in obesity-induced ferroptosis and cardiac injury was investigated. We found that Cel alleviated ferroptosis induced by Palmitic acid (PA), exhibiting a decrease in the LDH, CK-MB, Ptgs2, and Lipid Peroxidation levels. After cardiomyocytes were treated with additional LY294002 and LiCl, Cel exerted its protective effect through increased AKT/GSK3β phosphorylation and decreased level of lipid peroxidation and Mitochondrial ROS. The systolic left ventricle (LV) dysfunction of obese mice was alleviated via ferroptosis inhibition by elevated p-GSK3β and decreased Mitochondrial ROS under Cel treatment. Moreover, mitochondrial anomalies included swelling and distortion in the myocardium which was relieved with Cel. In conclusion, our results demonstrate that ferroptosis resistance with Cel under HFD conditions targets AKT/GSK3β signaling, which provides novel therapeutic strategies in obesity-induced cardiac injury.

Ro25-6981 alleviates neuronal damage and improves cognitive deficits by attenuating oxidative stress via the Nrf2/ARE pathway in ischemia/reperfusion rats

OBJECTIVES

Oxidative stress plays a crucial role in the initiation and progression of cerebral ischemia‒reperfusion injury (CIRI). Therefore, ameliorating oxidative damage is considered to be a beneficial strategy for the treatment of CIRI. NMDAR NR2B subunit antagonists have been reported to be beneficial for synaptic plasticity, neuropathic pain, epilepsy, and cerebral ischemia. However, it remains unclear whether the NR2B subunit antagonist Ro25-6981 has any effect on CIRI.

METHODS

In this study, the Morris water maze test and passive avoidance test were used to detect spatial learning and memory. Neuronal loss was measured by Nissl staining. The expression of NSE was assayed by immunohistochemistry. The activities of MDA, 8-OHdG, SOD, GSH-Px, GST and CAT were detected by assay kits. Real-time PCR was used to detect the mRNA levels of hippocampal SOD, GSH-Px and HO-1. Western blotting was used to measure the activation of the Nrf2/ARE pathway by Ro25-6981.

RESULTS

Ro25-6981 ameliorated cognitive deficits and neuronal damage induced by ischemia‒reperfusion (I/R). Neuronal injury was decreased and the expression of NSE was increased in the CA1 regions of the hippocampus of I/R rats after Ro25-6981 treatment. Moreover, Ro25-6981 alleviated the levels of MDA and 8-OHdG by elevating the activities of SOD, GSH-Px, GST and CAT. Meanwhile, the mRNA levels of SOD, GSH-Px and HO-1 were increased in I/R rats after Ro25-6981 treatment. Furthermore, Ro25-6981 promoted the translocation of Nrf2 to the nucleus, promoting the expression of the Nrf2 downstream genes HO-1 and NQO1.

CONCLUSION

The present study indicated that the improvement in the antioxidant properties of Ro25-6981 is mediated by the Nrf2/ARE pathway. This is the first study to demonstrate a favorable effect of Ro25-6981 on cognitive impairment in a CIRI rat model, rendering this NR2B subunit antagonist a promising agent for the treatment or prevention of CIRI.

Polysaccharide from Flammulina velutipes residues protects mice from Pb poisoning by activating Akt/GSK3β/Nrf-2/HO-1 signaling pathway and modulating gut microbiota

Lead (Pb) can cause damages to the brain, liver, kidney, endocrine and other systems. Flammulina velutipes residues polysaccharide (FVRP) has been reported to exhibit anti-heavy metal toxicity on yeast, but its regulating mechanism is unclear. Therefore, the protective effect and the underlying mechanism of FVRP on Pb-intoxicated mice were investigated. The results showed that FVRP could reduce liver and kidney function indexes, serum inflammatory factor levels, and increase antioxidant enzyme activity of Pb-poisoned mice. FVRP also exhibited a protective effect on histopathological damages in organs of Pb-intoxicated mice. Furthermore, FVRP attenuated Pb-induced kidney injury by inhibiting apoptosis via activating the Akt/GSK3β/Nrf-2/HO-1 signaling pathway. In addition, based on 16 s rRNA and ITS-2 sequencing data, FVRP regulated the imbalance of gut microbiota to alleviate the damage of Pb-poisoned mice by increasing the abundance of beneficial microbiota (Lachnospiraceae, Lactobacillaceae, Saccharomyces and Mycosphaerella) and decreasing the abundance of harmful microbiota (Muribaculaceae and Pleosporaceae). In conclusion, FVRP inhibited kidney injury in Pb-poisoned mice by inhibiting apoptosis via activating Akt/GSK3β/Nrf-2/HO-1 signaling pathway, and regulating gut fungi and gut bacteria. This study not only revealed the role of gut fungi in Pb-toxicity, but also laid a theoretical foundation for FVRP as a natural drug against Pb-toxicity.

Liraglutide Improves the Angiogenic Capability of EPC and Promotes Ischemic Angiogenesis in Mice under Diabetic Conditions through an Nrf2-Dependent Mechanism

The impairment in endothelial progenitor cell (EPC) functions results in dysregulation of vascular homeostasis and dysfunction of the endothelium under diabetic conditions. Improving EPC function has been considered as a promising strategy for ameliorating diabetic vascular complications. Liraglutide has been widely used as a therapeutic agent for diabetes. However, the effects and mechanisms of liraglutide on EPC dysfunction remain unclear. The capability of liraglutide in promoting blood perfusion and angiogenesis under diabetic conditions was evaluated in the hind limb ischemia model of diabetic mice. The effect of liraglutide on the angiogenic function of EPC was evaluated by cell scratch recovery assay, tube formation assay, and nitric oxide production. RNA sequencing was performed to assess the underlying mechanisms. Liraglutide enhanced blood perfusion and angiogenesis in the ischemic hindlimb of db/db mice and streptozotocin-induced type 1 diabetic mice. Additionally, liraglutide improved tube formation, cell migration, and nitric oxide production of high glucose (HG)-treated EPC. Assessment of liraglutide target pathways revealed a network of genes involved in antioxidant activity. Further mechanism study showed that liraglutide decreased the production of reactive oxygen species and increased the activity of nuclear factor erythroid 2-related factor 2 (Nrf2). Nrf2 deficiency attenuated the beneficial effects of liraglutide on improving EPC function and promoting ischemic angiogenesis under diabetic conditions. Moreover, liraglutide activates Nrf2 through an AKT/GSK3β/Fyn pathway, and inhibiting this pathway abolished liraglutide-induced Nrf2 activation and EPC function improvement. Overall, these results suggest that Liraglutide represents therapeutic potential in promoting EPC function and ameliorating ischemic angiogenesis under diabetic conditions, and these beneficial effects relied on Nrf2 activation.

Proteomics on the role of muscone in the "consciousness-restoring resuscitation" effect of musk on ischemic stroke

ETHNOPHARMACOLOGICAL RELEVANCE

Musk is a representative drug of aroma-relieving traditional Chinese medicine, and it is a commonly used traditional Chinese medicine for the treatment of ischemic stroke. Muscone is the core medicinal component of musk.

AIM OF THE STUDY

We sought to identify the target of muscone in the treatment of ischemic stroke using network pharmacology, an animal model of ischemic stroke, and differential proteomics.

MATERIALS AND METHODS

The drug targets of muscone in the treatment of ischemic stroke were predicted and analyzed using information derived from sources such as the Traditional Chinese Medicine Systems Pharmacology database and Swiss Target Prediction tool. The animal model of focal cerebral ischemia was established by suture-based occlusion of the middle cerebral artery of rats. The rats were divided into six groups: sham-operated control, model, musk, muscone1, muscone2, and muscone3. Neurological deficit scores were calculated after intragastric administration of musk or muscone. The microcirculation blood flow of the pia mater was detected using a laser speckle blood flow meter. The cerebral infarction rate was detected by 2,3,5-triphenyltetrazolium chloride staining. The necrosis rate of the cerebral cortex and the hippocampal neurons was detected by hematoxylin and eosin staining. Blood-brain barrier damage was detected by the Evans blue method. Quantitative proteomics analysis in the sham-operated control, model, and muscone groups was performed using tandem-mass-tags. Considering fold changes exceeding 1.2 as differential protein expression, the quantitative values were compared among groups by analysis of variance. Furthermore, a protein-protein interaction network was constructed, and differentially expressed proteins were analyzed by gene ontology (GO), and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis.

RESULTS

Network pharmacology identified 339 targets for the intersection of 17 components of musk and cerebral ischemia-reperfusion injury. The GO and KEGG enrichment items mainly identified regulation of neuronal synaptic structure and transfer function, synaptic neurotransmitters, and receptor activity. Zoopery showed that the model group had a higher behavioral score, cerebral infarction rate, cortical and hippocampal neuron death rate, Evans blue exudation in the brain, and bilateral pia mater microcirculation blood flow differences than the sham-operated control group (P <0.01). Compared with the model group, the behavioral score, infarction rate, hippocampal neuronal mortality, and Evans blue content decreased significantly in the musk, muscone2, and muscone3 groups (P <0.05). Proteomic analysis showed that 160 genes were differentially expressed among the sham-operated control, model, and muscone groups. GO items with high enrichment included neuronal synapses, postsynaptic signal transduction, etc. KEGG items with high enrichment included cholinergic synapses, calcium signaling pathway, dopaminergic synapses, etc. Protein interaction analysis revealed that the top three protein pairs were Ndufa10/Ndufa6, Kcna2/Kcnab2, and Gsk3b/Traf6.

CONCLUSIONS

Muscone can reduce neuronal necrosis, protect the blood-brain barrier, and improve the neurological damage caused by cerebral ischemia via molecular mechanisms mainly involving the regulation of neuronal synaptic connections. Muscone is an important active component responsible for the "consciousness-restoring resuscitation" effect of musk on ischemic stroke.

Flurochloridone induces responses of free radical reactions and energy metabolism disorders to BRL-3A cell

Flurochloridone (FLC), a wildly used herbicide, could induce hepatotoxicity after long-term exposure to male rat, in addition to its reactive oxygen species (ROS)-dependent reproductive toxicity. The hepatotoxicity effect and mechanism was investigeted using 1, 10 and 100 μmol L^-1 FLC treated BRL-3A liver cell in this study. The function of mitochondrial respiration, glycolysis rate and real time ATP production rate are determined by seahorse XF analyzer, and the bio-transformers of FLC, intermediates of TCA cycle and glycolysis, and related amino acids are determined and identified by [U-¹³C] Glucose metabolic flux technology based on UPLC-HRMS. The mRNA expression of cytochrome P450s and the key regulatory enzymes of glucose metabolism and γ- glutamyl cycle pathway. The protein expressions of protein kinase B (AKT) and glycogen synthase kinase-3 beta (GSK-3β) were determined. The results show dechlorination and glutathione (GSH) conjugate products of FLC are predominant bio-transformmers after 24 h treatment in BRL-3A cell. FLC could enhance glycolysis function and inhibit mitochondrial aerobic respiratory, which is accompanied by the decreased total ATP level and ATP produced rate. Increased glucose-6-phosphate, fructose-6-phosphate, pyruvate and lactate levels, and elevated level of GSH and its precursor 5-glutamate-cysteine (γ-Glu-Cys) are observed in FLC treated cells, which indicates that energy metabolism dysfunction and GSH accumulation could be potentially mediated by activating γ- Glutamyl cycle pathway. Conclusively, FLC induced hepatotoxicity could be potentially related to some free radical reactions, including inhibiting mitochondrial function, glucose metabolism via glycolysis, regulating γ- glutamyl cycle pathway to promote reactive oxygen species (ROS) level, and then induced cell apoptosis by inhibiting AKT/GSK-3β signal.

Monosodium Glutamate-Induced Mouse Model With Unique Diabetic Retinal Neuropathy Features and Artificial Intelligence Techniques for Quantitative Evaluation

Objective

To establish an artificial intelligence-based method to quantitatively evaluate subtle pathological changes in retinal nerve cells and synapses in monosodium glutamate (MSG) mice and provide an effective animal model and technique for quantitative evaluation of retinal neurocytopathies.

Methods

ICR mice were subcutaneously injected with MSG to establish a model of metabolic syndrome. We then established a mouse model of type 1 diabetes, type 2 diabetes, and KKAy mouse model as control. The HE sections of the retina were visualized using an optical microscope. AI technology was used for quantitative evaluation of the retinal lesions in each group of rats. The surface area custom parameters of the retinal nerve fiber layer (RNFL), inner plexiform layer (IPL), inner nuclear layer (INL), and outer plexiform layer (OPL) were defined as SR, SIPL, SINL, and SOPL, respectively. Their heights were defined as HR, HIPL, HINL, and HOPL, and the number of ganglion cells was defined as A. Then, the attention-augmented fully convolutional Unet network was used to segment the retinal HE images, and AI technology to identify retinal neurocytopathies quantitatively.

Results

The attention-augmented fully convolutional Unet network increased PA and IOU parameters for INL, OPL, RNFL, and ganglion cells and was superior in recognizing fine structures. A quantitative AI identification of the height of each layer of the retina showed that the heights of the IPL and INL of the MSG model were significantly less than those of the control groups; the retinas of the other diabetic models did not exhibit this pathological feature. The RNFLs of type 2 diabetes were thinner, and the characteristics of retinopathy were not obvious in the other animal models. The pathological changes seen on HE images were consistent with the results of the quantitative AI evaluation. Immunohistochemistry results showed that NMDAR2A, GluR2, and NRG1 were significantly downregulated in the retina of MSG mice.

Conclusions

The MSG retinopathy model is closely associated with neurotransmitter abnormalities and exhibits important characteristics of retinal neurodegeneration, making it suitable for studying retinal neurocytopathies. The AI recognition technology for retinal images established in the present study can be used for the quantitative and objective evaluation of drug efficacy.