Interaction of oxidative stress and neurotrauma in ALDH2-/- mice causes significant and persistent behavioral and pro-inflammatory effects in a tractable model of mild traumatic brain injury

Repetitive traumatic brain injury-induced complement C1-related inflammation impairs long-term hippocampal neurogenesis

JOURNAL/nrgr/04.03/01300535-202503000-00027/figure1/v/2024-06-17T092413Z/r/image-tiff Repetitive traumatic brain injury impacts adult neurogenesis in the hippocampal dentate gyrus, leading to long-term cognitive impairment. However, the mechanism underlying this neurogenesis impairment remains unknown. In this study, we established a male mouse model of repetitive traumatic brain injury and performed long-term evaluation of neurogenesis of the hippocampal dentate gyrus after repetitive traumatic brain injury. Our results showed that repetitive traumatic brain injury inhibited neural stem cell proliferation and development, delayed neuronal maturation, and reduced the complexity of neuronal dendrites and spines. Mice with repetitive traumatic brain injuryalso showed deficits in spatial memory retrieval. Moreover, following repetitive traumatic brain injury, neuroinflammation was enhanced in the neurogenesis microenvironment where C1q levels were increased, C1q binding protein levels were decreased, and canonical Wnt/β-catenin signaling was downregulated. An inhibitor of C1 reversed the long-term impairment of neurogenesis induced by repetitive traumatic brain injury and improved neurological function. These findings suggest that repetitive traumatic brain injury-induced C1-related inflammation impairs long-term neurogenesis in the dentate gyrus and contributes to spatial memory retrieval dysfunction.

The role of ALDHs in lipid peroxidation-related diseases

Lipid peroxidation presents the oxidative degradation of polyunsaturated fatty acids lincited by reactive species. Excessive accumulation of lipid peroxidation byproducts, including 4-hydroxy-2-nonenal (4-HNE) and malondialdehyde (MDA), causes protein dysfunction and various illnesses. Aldehyde dehydrogenases (ALDHs) catalyze the metabolism of both endogenous and exogenous aldehydes. These enzymes participate in detoxification and intermediary metabolism. Contemporary research has affirmed the involvement of both enzymatic and non-enzymatic pathways of ALDHs in modulating the evolution of diseases associated with lipid peroxidation. This review provides an overview of the biological functions and clinical implications concerning the enzymatic and non-enzymatic pathways of ALDHs in diseases related to lipid peroxidation, such as, non-alcoholic fatty liver disease (NAFLD), atherosclerosis, and type 2 diabetes (T2DM). Furthermore, the activators or inhibitors of ALDHs represent a promising therapeutic strategy for lipid peroxidation-related diseases.

Comparative Proteomic Analysis of Endolymphatic Sac Luminal Fluid in Patients with Meniere's Disease and Controls

Introduction

Meniere's disease (MD) is known to be caused by the dysfunction of the endolymphatic sac (ES), but its molecular mechanism is unknown.

Methods

We performed a comparative proteomic analysis of ES luminal fluids (ELFs) from patients with MD and controls.

Results

We found 6 differentially expressed proteins, including 2 significantly increased proteins and 4 significantly decreased proteins, 8 proteins identified exclusively in at least 7 of the 8 ELF samples from MD patients and 3 proteins detected solely in at least 4 of the 5 ELF samples from controls.

Discussion

The increased levels of IGLV 3-9 and IGLV1-47 in MD group compared with control group suggested an increased inflammatory reactions and a decreased level of Aldehyde dehydrogenase 2 in MD group compared with control group might result in oxidative damage and inflammatory lesions in the ES of MD. Whereas CD44 identified exclusively in MD samples might be involved in the metabolism of its ligand, hyaluronic acid for overproduction of endolymph in the ES of MD.

The role of ALDH2 rs671 polymorphism and C-reactive protein in the phenotypes of male ALS patients

Background

The aldehyde dehydrogenase 2 (ALDH2) rs671 (A) allele has been implicated in neurodegeneration, potentially through oxidative and inflammatory pathways. The study aims to investigate the effects of the ALDH2 rs671 (A) allele and high sensitivity C-reactive protein (hs-CRP) on the clinical phenotypes of amyotrophic lateral sclerosis (ALS) in male and female patients.

Methods

Clinical data and ALDH2 rs671 genotype of 143 ALS patients, including 85 males and 58 females, were collected from January 2018 to December 2022. All patients underwent assessment using the Chinese version of the Edinburgh Cognitive and Behavioral ALS Screen (ECAS). Complete blood count and metabolic profiles were measured. Clinical and laboratory parameters were compared between carriers and non-carriers of the rs671 (A) allele in males and females, respectively. The significant parameters and rs671 (A) Allele were included in multivariate linear regression models to identify potential contributors to motor and cognitive impairment. Mediation analysis was employed to evaluate any mediation effects.

Results

Male patients carrying rs671 (A) allele exhibited higher levels of hs-CRP than non-carriers (1.70 mg/L vs. 0.50 mg/L, p = 0.006). The rs671 (A) allele was identified as an independent risk factor for faster disease progression only in male patients (β = 0.274, 95% CI = 0.048-0.499, p = 0.018). The effect of the rs671 (A) allele on the executive function in male patients was fully mediated by hs-CRP (Indirect effect = -1.790, 95% CI = -4.555--0.225). No effects of the rs671 (A) allele or hs-CRP were observed in female ALS patients. The effects of the ALDH2 rs671 (A) allele and the mediating role of hs-CRP in male patients remained significant in the sensitivity analyses.

Conclusion

The ALDH2 rs671 (A) allele contributed to faster disease progression and hs-CRP mediated cognitive impairment in male ALS patients.

Beta2 adrenergic receptor-mediated abnormal myelopoiesis drives neuroinflammation in aged patients with traumatic brain injury

Aged patients often suffer poorer neurological recovery than younger patients after traumatic brain injury (TBI), but the mechanisms underlying this difference remain unclear. Here, we demonstrate abnormal myelopoiesis characterized by increased neutrophil and classical monocyte output but impaired nonclassical patrolling monocyte population in aged patients with TBI as well as in an aged murine TBI model. Retrograde and anterograde nerve tracing indicated that increased adrenergic input through the central amygdaloid nucleus-bone marrow axis drives abnormal myelopoiesis after TBI in a β2-adrenergic receptor-dependent manner, which is notably enhanced in aged mice after injury. Selective blockade of β2-adrenergic receptors rebalances abnormal myelopoiesis and improves the outcomes of aged mice after TBI. We therefore demonstrate that increased β2-adrenergic input-driven abnormal myelopoiesis exacerbates post-TBI neuroinflammation in the aged, representing a mechanism underlying the poorer recovery of aged patients and that blockade of β2-adrenergic receptor is a potential approach to promote neurological recovery after TBI.

Mitochondrial Aldehyde Dehydrogenase 2 (ALDH2) Protects against Binge Alcohol-Mediated Gut and Brain Injury

Mitochondrial aldehyde dehydrogenase-2 (ALDH2) metabolizes acetaldehyde to acetate. People with ALDH2 deficiency and Aldh2-knockout (KO) mice are more susceptible to alcohol-induced tissue damage. However, the underlying mechanisms behind ALDH2-related gut-associated brain damage remain unclear. Age-matched young female Aldh2-KO and C57BL/6J wild-type (WT) mice were gavaged with binge alcohol (4 g/kg/dose, three doses) or dextrose (control) at 12 h intervals. Tissues and sera were collected 1 h after the last ethanol dose and evaluated by histological and biochemical analyses of the gut and hippocampus and their extracts. For the mechanistic study, mouse neuroblast Neuro2A cells were exposed to ethanol with or without an Aldh2 inhibitor (Daidzin). Binge alcohol decreased intestinal tight/adherens junction proteins but increased oxidative stress-mediated post-translational modifications (PTMs) and enterocyte apoptosis, leading to elevated gut leakiness and endotoxemia in Aldh2-KO mice compared to corresponding WT mice. Alcohol-exposed Aldh2-KO mice also showed higher levels of hippocampal brain injury, oxidative stress-related PTMs, and neuronal apoptosis than the WT mice. Additionally, alcohol exposure reduced Neuro2A cell viability with elevated oxidative stress-related PTMs and apoptosis, all of which were exacerbated by Aldh2 inhibition. Our results show for the first time that ALDH2 plays a protective role in binge alcohol-induced brain injury partly through the gut-brain axis, suggesting that ALDH2 is a potential target for attenuating alcohol-induced tissue injury.

Impact of common ALDH2 inactivating mutation and alcohol consumption on Alzheimer's disease

Aldehyde dehydrogenase 2 (ALDH2) is an enzyme found in the mitochondrial matrix that plays a central role in alcohol and aldehyde metabolism. A common ALDH2 polymorphism in East Asians descent (called ALDH2*2 or E504K missense variant, SNP ID: rs671), present in approximately 8% of the world's population, has been associated with a variety of diseases. Recent meta-analyses support the relationship between this ALDH2 polymorphism and Alzheimer's disease (AD). And AD-like pathology observed in ALDH2-/- null mice and ALDH2*2 overexpressing transgenic mice indicate that ALDH2 deficiency plays an important role in the pathogenesis of AD. Recently, the worldwide increase in alcohol consumption has drawn attention to the relationship between heavy alcohol consumption and AD. Of potential clinical significance, chronic administration of alcohol in ALDH2*2/*2 knock-in mice exacerbates the pathogenesis of AD-like symptoms. Therefore, ALDH2 polymorphism and alcohol consumption likely play an important role in the onset and progression of AD. Here, we review the data on the relationship between ALDH2 polymorphism, alcohol, and AD, and summarize what is currently known about the role of the common ALDH2 inactivating mutation, ALDH2*2, and alcohol in the onset and progression of AD.

Environmental enrichment improves traumatic brain injury-induced behavioral phenotype and associated neurodegenerative process

Traumatic brain injury (TBI) causes persistent cognitive impairment and neurodegeneration. Environmental enrichment (EE) refers to a housing condition that promotes sensory and social stimulation and improves cognition and motor performance but the underlying mechanisms responsible for such beneficial effects are not well defined. In this study, anesthetized adult rats received either a moderate-to-severe controlled cortical impact (CCI) or sham surgery and then were housed in either EE or standard conditions. The results showed a significant increase in protein nitration and oxidation of lipids, impaired cognition and motor performance, and augmented N-methyl-d-aspartate receptor subtype-1 (NMDAR1) levels. However, EE initiated 24 h after CCI resulted in reduced oxidative insult and microglial activation and significant improvement in beam-balance/walk performance and both spatial learning and memory. We hypothesize that following TBI there is an upstream activation of NMDAR that promotes oxidative insult and an inflammatory response, thereby resulting in impaired behavioral functioning but EE may exert a neuroprotective effect via sustained downregulation of NMDAR1.

High Dimensional Multiomics Reveals Unique Characteristics of Early Plasma Administration in Polytrauma Patients With TBI

OBJECTIVES

The authors sought to identify causal factors that explain the selective benefit of prehospital administration of thawed plasma (TP) in traumatic brain injury (TBI) patients using mediation analysis of a multiomic database.

BACKGROUND

The Prehospital Air Medical Plasma (PAMPer) Trial showed that patients with TBI and a pronounced systemic response to injury [defined as endotype 2 (E2)], have a survival benefit from prehospital administration of TP. An interrogation of high dimensional proteomics, lipidomics and metabolomics previously demonstrated unique patterns in circulating biomarkers in patients receiving prehospital TP, suggesting that a deeper analysis could reveal causal features specific to TBI patients.

METHODS

A novel proteomic database (SomaLogic Inc., aptamer-based assay, 7K platform) was generated using admission blood samples from a subset of patients (n=149) from the PAMPer Trial. This proteomic dataset was combined with previously reported metabolomic and lipidomic datasets from these same patients. A 2-step analysis was performed to identify factors that promote survival in E2-TBI patients who had received early TP. First, features were selected using both linear and multivariate-latent-factor regression analyses. Then, the selected features were entered into the causal mediation analysis.

RESULTS

Causal mediation analysis of observable features identified 16 proteins and 41 lipids with a high proportion of mediated effect (>50%) to explain the survival benefit of early TP in E2-TBI patients. The multivariate latent-factor regression analyses also uncovered 5 latent clusters of features with a proportion effect >30%, many in common with the observable features. Among the observable and latent features were protease inhibitors known to inhibit activated protein C and block fibrinolysis (SERPINA5 and CPB2), a clotting factor (factor XI), as well as proteins involved in lipid transport and metabolism (APOE3 and sPLA(2)-XIIA).

CONCLUSIONS

These findings suggest that severely injured patients with TBI process exogenous plasma differently than those without TBI. The beneficial effects of early TP in E2-TBI patients may be the result of improved blood clotting and the effect of brain protective factors independent of coagulation.

Neuroprotective effects of Alda-1 mitigate spinal cord injury in mice: involvement of Alda-1-induced ALDH2 activation-mediated suppression of reactive aldehyde mechanisms

Spinal cord injury (SCI) is associated with high production and excessive accumulation of pathological 4-hydroxy-trans-2-nonenal (4-HNE), a reactive aldehyde, formed by SCI-induced metabolic dysregulation of membrane lipids. Reactive aldehyde load causes redox alteration, neuroinflammation, neurodegeneration, pain-like behaviors, and locomotion deficits. Pharmacological scavenging of reactive aldehydes results in limited improved motor and sensory functions. In this study, we targeted the activity of mitochondrial enzyme aldehyde dehydrogenase 2 (ALDH2) to detoxify 4-HNE for accelerated functional recovery and improved pain-like behavior in a male mouse model of contusion SCI. N-(1,3-benzodioxol-5-ylmethyl)-2,6-dichlorobenzamide (Alda-1), a selective activator of ALDH2, was used as a therapeutic tool to suppress the 4-HNE load. SCI was induced by an impactor at the T9–10 vertebral level. Injured animals were initially treated with Alda-1 at 2 hours after injury, followed by once-daily treatment with Alda-1 for 30 consecutive days. Locomotor function was evaluated by the Basso Mouse Scale, and pain-like behaviors were assessed by mechanical allodynia and thermal algesia. ALDH2 activity was measured by enzymatic assay. 4-HNE protein adducts and enzyme/protein expression levels were determined by western blot analysis and histology/immunohistochemistry. SCI resulted in a sustained and prolonged overload of 4-HNE, which parallels with the decreased activity of ALDH2 and low functional recovery. Alda-1 treatment of SCI decreased 4-HNE load and enhanced the activity of ALDH2 in both the acute and the chronic phases of SCI. Furthermore, the treatment with Alda-1 reduced neuroinflammation, oxidative stress, and neuronal loss and increased adenosine 5′-triphosphate levels stimulated the neurorepair process and improved locomotor and sensory functions. Conclusively, the results provide evidence that enhancing the ALDH2 activity by Alda-1 treatment of SCI mice suppresses the 4-HNE load that attenuates neuroinflammation and neurodegeneration, promotes the neurorepair process, and improves functional outcomes. Consequently, we suggest that Alda-1 may have therapeutic potential for the treatment of human SCI. Animal procedures were approved by the Institutional Animal Care and Use Committee (IACUC) of MUSC (IACUC-2019-00864) on December 21, 2019.

Neuronal Calcium Imaging, Excitability, and Plasticity Changes in the Aldh2-/- Mouse Model of Sporadic Alzheimer's Disease

Background:

Dysregulated signaling in neurons and astrocytes participates in pathophysiological alterations seen in the Alzheimer’s disease brain, including increases in amyloid-β, hyperphosphorylated tau, inflammation, calcium dysregulation, and oxidative stress. These are often noted prior to the development of behavioral, cognitive, and non-cognitive deficits. However, the extent to which these pathological changes function together or independently is unclear.

Objective:

Little is known about the temporal relationship between calcium dysregulation and oxidative stress, as some reports suggest that dysregulated calcium promotes increased formation of reactive oxygen species, while others support the opposite. Prior work has quantified several key outcome measures associated with oxidative stress in aldehyde dehydrogenase 2 knockout (Aldh2^–/–) mice, a non-transgenic model of sporadic Alzheimer’s disease.

Methods:

Here, we tested the hypothesis that early oxidative stress can promote calcium dysregulation across aging by measuring calcium-dependent processes using electrophysiological and imaging methods and focusing on the afterhyperpolarization (AHP), synaptic activation, somatic calcium, and long-term potentiation in the Aldh2^–/– mouse.

Results:

Our results show a significant age-related decrease in the AHP along with an increase in the slow AHP amplitude in Aldh2^–/– animals. Measures of synaptic excitability were unaltered, although significant reductions in long-term potentiation maintenance were noted in the Aldh2^–/– animals compared to wild-type.

Conclusion:

With so few changes in calcium and calcium-dependent processes in an animal model that shows significant increases in HNE adducts, Aβ, p-tau, and activated caspases across age, the current findings do not support a direct link between neuronal calcium dysregulation and uncontrolled oxidative stress.

Operationally defining cognitive reserve genes

Variability in cognitive decline is related to the environment, lifestyle factors, and individual differences in biological aging, including cognitive reserve, plastic properties of the brain, which account for better-than-expected cognition for a given level of brain aging or pathology. Cognitive reserve has not been thoroughly investigated in aged rodents. To address this gap, cognitive reserve was examined using Gene Expression Omnibus data for the CA1 region of the hippocampus of young and aged behaviorally characterized male rats. Statistical filtering identified brain aging and potential cognitive reserve genes, and multiple regression was employed to confirm cognitive reserve genes as genes that predicted better-than-expected cognition for a given level of brain aging. In general, cognitive reserve genes, in which increased expression was associated with better cognition, were not different with age or directly correlated with measures of cognition and appear to act as negative regulators of aging processes, including neuroinflammation and oxidative stress. The results suggest that, for some animals, resilience mechanisms are activated to counteract aging stressors that impair cognition. In contrast, cognitive reserve genes, in which decreased expression was associated with better cognition, were linked to nervous system development and cation transport, suggesting adaptive changes in the circuit to preserve cognition.

Late-life intermittent fasting decreases aging-related frailty and increases renal hydrogen sulfide production in a sexually dimorphic manner

Global average life expectancy continues to rise. As aging increases the likelihood of frailty, which encompasses metabolic, musculoskeletal, and cognitive deficits, there is a need for effective anti-aging treatments. It is well established in model organisms that dietary restriction (DR), such as caloric restriction or protein restriction, enhances health and lifespan. However, DR is not widely implemented in the clinic due to patient compliance and its lack of mechanistic underpinnings. Thus, the present study tested the effects of a somewhat more clinically applicable and adoptable DR regimen, every-other-day (EOD) intermittent fasting, on frailty in 20-month-old male and female C57BL/6 mice. Frailty was determined by a series of metabolic, musculoskeletal, and cognitive tasks performed prior to and toward the end of the 2.5-month dietary intervention. Late-life EOD fasting attenuated overall energy intake, hypothalamic inflammatory gene expression, and frailty in males. However, it failed to reduce overall caloric intake and had a little positive effect in females. Given that the selected benefits of DR are dependent on augmented production of the gasotransmitter hydrogen sulfide (H₂S) and that renal H₂S production declines with age, we tested the effects of EOD fasting on renal H₂S production capacity and its connection to frailty in males. EOD fasting boosted renal H₂S production, which positively correlated with improvements in multiple components of frailty tasks. Therefore, late-life initiated EOD fasting is sufficient to reduce aging-related frailty, at least in males, and suggests that renal H₂S production capacity may modulate the effects of late-life EOD fasting on frailty.

Discovery of Nonlipogenic ABCA1 Inducing Compounds with Potential in Alzheimer's Disease and Type 2 Diabetes

Selective liver X receptor (LXR) agonists have been extensively pursued as therapeutics for Alzheimer's disease and related dementia (ADRD) and, for comorbidities such as type 2 diabetes (T2D) and cerebrovascular disease (CVD), disorders with underlying impaired insulin signaling, glucose metabolism, and cholesterol mobilization. The failure of the LXR-focused approach led us to pursue a novel strategy to discover nonlipogenic ATP-binding cassette transporter A1 (ABCA1) inducers (NLAIs): screening for ABCA1-luciferase activation in astrocytoma cells and counterscreening against lipogenic gene upregulation in hepatocarcinoma cells. Beneficial effects of LXRβ agonists mediated by ABCA1 include the following: control of cholesterol and phospholipid efflux to lipid-poor apolipoproteins forming beneficial peripheral HDL and HDL-like particles in the brain and attenuation of inflammation. While rare, ABCA1 variants reduce plasma HDL and correlate with an increased risk of ADRD and CVD. In secondary assays, NLAI hits enhanced cholesterol mobilization and positively impacted in vitro biomarkers associated with insulin signaling, inflammatory response, and biogenic properties. In vivo target engagement was demonstrated after oral administration of NLAIs in (i) mice fed a high-fat diet, a model for obesity-linked T2D, (ii) mice administered LPS, and (iii) mice with accelerated oxidative stress. The lack of adverse effects on lipogenesis and positive effects on multiple biomarkers associated with T2D and ADRD supports this novel phenotypic approach to NLAIs as a platform for T2D and ADRD drug discovery.

Extending the Calpain-Cathepsin Hypothesis to the Neurovasculature: Protection of Brain Endothelial Cells and Mice from Neurotrauma

The calpain-cathepsin hypothesis posits a key role for elevated calpain-1 and cathepsin-B activity in the neurodegeneration underlying neurotrauma and multiple disorders including Alzheimer's disease (AD). AD clinical trials were recently halted on alicapistat, a selective calpain-1 inhibitor, because of insufficient exposure of neurons to the drug. In contrast to neuroprotection, the ability of calpain-1 and cathepsin-B inhibitors to protect the blood-brain barrier (BBB), is understudied. Since cerebrovascular dysfunction underlies vascular dementia, is caused by ischemic stroke, and is emerging as an early feature in the progression of AD, we studied protection of brain endothelial cells (BECs) by selective and nonselective calpain-1 and cathepsin-B inhibitors. We show these inhibitors protect both neurons and murine BECs from ischemia-reperfusion injury. Cultures of primary BECs from ALDH2 ^-/- mice that manifest enhanced oxidative stress were sensitive to ischemia, leading to reduced cell viability and loss of tight junction proteins; this damage was rescued by calpain-1 and cathepsin-B inhibitors. In ALDH2 ^-/- mice 24 h after mild traumatic brain injury (mTBI), BBB damage was reflected by significantly increased fluorescein extravasation and perturbation of tight junction proteins, eNOS, MMP-9, and GFAP. Both calpain and cathepsin-B inhibitors alleviated BBB dysfunction caused by mTBI. No clear advantage was shown by selective versus nonselective calpain inhibitors in these studies. The lack of recognition of the ability of calpain inhibitors to protect the BBB may have led to the premature abandonment of this therapeutic approach in AD clinical trials and requires further mechanistic studies of cerebrovascular protection by calpain-1 inhibitors.

Age-Related Neuronal Deterioration Specifically Within the Dorsal CA1 Region of the Hippocampus in a Mouse Model of Late Onset Alzheimer's Disease

BACKGROUND

Neuronal damage resulting from increased oxidative stress is important in the development of late onset/age-related Alzheimer's disease (LOAD). We have developed an oxidative stress-related mouse model of LOAD based on gene deletion of aldehyde dehydrogenase 2 (ALDH2), an enzyme important for the detoxification of endogenous aldehydes arising from lipid peroxidation. Compared to wildtype (WT) mice, the knockout (KO) mice exhibit AD-like pathologies and a progressive decline in recognition and spatial memory. This progression presumably has a morphological basis induced by oxidative damage.

OBJECTIVE

We performed morphometric analyses in the dorsal hippocampal CA1 region (dCA1) to determine if altered neuronal structure can help account for the progressive cognitive impairment in 3- to 12-month-old KO mice.

METHODS

Dendritic morphology was quantitatively analyzed by branched structured analysis and Sholl analysis following Golgi-Cox staining in WT mice (148 neurons) versus KO mice (180 neurons).

RESULTS

The morphology and complexity of dCA1 pyramidal neurons were similar at age 3 months in WTs and KOs. However, by 6 months there were significant reductions in apical and basal dendritic length, dendrite complexity, and spine density in KO versus WT mice that were maintained through ages 9 and 12 months. Immunostaining for protein adducts of the lipid peroxidation product 4-hydroxynonenal revealed significant increases in staining in dCA1 (but not ventral CA1) by 3 months, increasing through 12 months.

CONCLUSION

This specific and progressive increase in dCA1 oxidative damage preceded detectable synaptic trimming in KO mice, in keeping with studies showing that lesions to dorsal hippocampus primarily impair cognitive memory.

Expression of Neuronal Na+/K+-ATPase α Subunit Isoforms in the Mouse Brain Following Genetically Programmed or Behaviourally-induced Oxidative Stress

The Na⁺/K⁺-ATPase is a transmembrane ion pump that has a critical homeostatic role within every mammalian cell; however, it is vulnerable to the effects of increased oxidative stress. Understanding how expression of this transporter is influenced by oxidative stress may yield insight into its role in the pathophysiology of neurological and neuropsychiatric diseases. In this study we investigated whether increased oxidative stress could influence Na⁺/K⁺-ATPase expression in various brain regions of mice. We utilized two different models of oxidative stress: a behavioural chronic unpredictable stress protocol and the Aldh2^-/- mouse model of oxidative stress-based and age-related cognitive impairment. We identified distinct regional baseline mRNA and protein expression patterns of the Na⁺/K⁺-ATPase α1 and α3 isoforms within the neocortex, hippocampus, and brainstem of wildtype mice. Consistent with previous studies, there was a higher proportion of α3 expression relative to α1 in the brainstem versus neocortex, but a higher proportion of α1 expression relative to α3 in the neocortex versus the brainstem. The hippocampus had similar expression levels of both α1 and α3. Despite increased staining for oxidative stress in higher brain, no differences in α1 or α3 expression were noted in Aldh2^-/- mice versus wildtype, or in mice exposed to a 28-day chronic unpredictable stress protocol. In both models of oxidative stress, gene and protein expression of Na⁺/K⁺-ATPase α1 and α3 isoforms within the higher and lower brain was remarkably stable. Thus, Na⁺/K⁺-ATPase function previously reported as altered by oxidative stress is not through induced changes in the expression of pump isoforms.