Treadmill exercise ameliorates symptoms of Alzheimer disease through suppressing microglial activation-induced apoptosis in rats

Exercise as a Therapeutic Strategy for Obesity: Central and Peripheral Mechanisms

Obesity is a complex, multifactorial condition involving excessive fat accumulation due to an imbalance between energy intake and expenditure, with its global prevalence steadily rising. This condition significantly increases the risk of chronic diseases, including sarcopenia, type 2 diabetes, and cardiovascular diseases, highlighting the need for effective interventions. Exercise has emerged as a potent non-pharmacological approach to combat obesity, targeting both central and peripheral mechanisms that regulate metabolism, energy expenditure, and neurological functions. In the central nervous system, exercise influences appetite, mood, and cognitive functions by modulating the reward system and regulating appetite-controlling hormones to manage energy intake. Concurrently, exercise promotes thermogenesis in adipose tissue and regulates endocrine path-ways and key metabolic organs, such as skeletal muscle and the liver, to enhance fat oxidation and support energy balance. Despite advances in understanding exercise's role in obesity, the precise interaction between the neurobiological and peripheral metabolic pathways remains underexplored, particularly in public health strategies. A better understanding of these interactions could inform more comprehensive obesity management approaches by addressing both central nervous system influences on behavior and peripheral metabolic regulation. This review synthesizes recent insights into these roles, highlighting potential therapeutic strategies targeting both systems for more effective obesity interventions.

Exercise Improves Cerebral Blood Flow and Functional Outcomes in an Experimental Mouse Model of Vascular Cognitive Impairment and Dementia (VCID)

Vascular cognitive impairment and dementia (VCID) are a growing threat to public health without any known treatment. The bilateral common carotid artery stenosis (BCAS) mouse model is valid for VCID. Previously, we have reported that remote ischemic postconditioning (RIPostC) during chronic cerebral hypoperfusion (CCH) induced by BCAS increases cerebral blood flow (CBF), improves cognitive function, and reduces white matter damage. We hypothesized that physical exercise (EXR) would augment CBF during CCH and prevent cognitive impairment in the BCAS model. BCAS was performed in C57/B6 mice of both sexes to establish CCH. One week after the BCAS surgery, mice were randomized to treadmill exercise once daily or no EXR for four weeks. CBF was monitored with an LSCI pre-, post, and 4 weeks post-BCAS. Cognitive testing was performed for post-BCAS after exercise training, and brain tissue was harvested for histopathology and biochemical test. BCAS led to chronic hypoperfusion resulting in impaired cognitive function and other functional outcomes. Histological examination revealed that BCAS caused changes in neuronal morphology and cell death in the cortex and hippocampus. Immunoblotting showed that BCAS was associated with a significant downregulate of AMPK and pAMPK and NOS3 and pNOS3. BCAS also decreased red blood cell (RBC) deformability. EXR therapy increased and sustained improved CBF and cognitive function, muscular strength, reduced cell death, and loss of white matter. EXR is effective in the BCAS model, improving CBF and cognitive function, reducing white matter damage, improving RBC deformability, and increasing RBC NOS3 and AMPK. The mechanisms by which EXR improves CBF and attenuates tissue damage need further investigation.

High-intensity interval training combined with cannabidiol supplementation improves cognitive impairment by regulating the expression of apolipoprotein E, presenilin-1, and glutamate proteins in a rat model of amyloid β-induced Alzheimer's disease

Objectives

Alzheimer's disease (AD) is a major public concern and one of the primary types of dementia characterized by memory impairment and cognitive decline. Although the properties of exercise training and cannabidiol (CBD) treatments for improving AD have recently been revealed, the exact mechanisms remain unknown. Therefore, this study highlights the interactive impact of high-intensity interval training (HIIT) and CBD administration on improving cognitive impairment in a rat model of amyloid beta (Aꞵ)-induced AD through modulating the expression of apolipoprotein E (APOE), presenilin-1, and glutamate proteins.

Materials and Methods

After acclimatization, the animals were randomly assigned into seven subgroups: control (CNT), Sham, Alzheimer (AL), Alzheimer + HIIT (AL + HIIT), Alzheimer + cannabidiol (AL + CBD), Alzheimer + CBD + HIIT (AL + CBD + HIIT), and model (sacrificed ten days after surgery to confirm the induction of AD) groups. To induce AD, rats received an intrahippocampal injection of Aꞵ. The animals in exercise groups performed the HIIT protocol, and the rats in CBD groups were administered 20 mg/kg CBD suspended in sesame oil for six weeks. Following the experimental protocol, serum and hippocampus tissue were collected for histopathological and western blot analysis.

Results

Our findings indicated that both HIIT and CBD treatments were efficacious in ameliorating Aꞵ deposition and modulating biomarkers of AD, including APOE, presenilin-1, and glutamate. However, the interactive effect of HIIT and CBD supplementation was more effective.

Conclusion

Our findings demonstrated the positive therapeutic effect of HIIT and CBD interventions, particularly HIIT combined with CBD, on alleviating AD.

TRPA1 as a promising target in ischemia/reperfusion: A comprehensive review

Ischemic disorders, including myocardial infarction, cerebral ischemia, and peripheral vascular impairment, are the main common reasons for debilitating diseases and death in Western cultures. Ischemia occurs when blood circulation is reduced in tissues. Reperfusion, although commanded to return oxygen to ischemic tissues, generates paradoxical tissue responses. The responses include generating reactive oxygen species (ROS), stimulating inflammatory responses in ischemic organs, endoplasmic reticulum stress, and the expansion of postischemic capillary no-reflow, which intensifies organ damage. Multiple pathologic processes contribute to ischemia/reperfusion; therefore, targeting different pathologic processes may yield an effective therapeutic approach. Transient Receptor Potential A1 (TRPA1) belongs to the TRP family of ion channels, detects a broad range of chemicals, and promotes the transduction of noxious stimuli, e.g., methylglyoxal, ROS, and acrolein effects are attributed to the channel's sensitivity to intracellular calcium elevation or phosphoinositol phosphate modulation. Hypoxia and ischemia are associated with oxidative stress, which activates the TRPA1 channel. This review describes the role of TRPA1 and its related mechanisms that contribute to ischemia/reperfusion. Relevant articles were searched from PubMed, Scopus, Web of Sciences, and Google Scholar electronic databases, up to the end of August 2023. Based on the evidence presented here, TRPA1 may have protective or deteriorative functions during the ischemia/reperfusion process. Its function depends on the activation level, the ischemic region, the extent of lesions, and the duration of ischemia.

Protective effect of a standardized Allium jesdianum extract in an Alzheimer's disease induced rat model

Alzheimer's disease (AD) is a complex disorder with multiple underlying mechanisms. Existing treatment options mostly address symptom management and are associated with numerous side effects. Therefore, exploring alternative therapeutic agents derived from medicinal plants, which contain various bioactive compounds with diverse pharmacological effects, holds promise for AD treatment. This study aims to assess the protective effects of the hydroalcoholic extract of Allium jesdianum on cognitive dysfunction, mitochondrial and cellular parameters, as well as genetic parameters in an intracerebroventricular Streptozotocin (icv-STZ) induced rat model of AD. Male Wistar rats were injected with a single dose of STZ (3 mg/kg, icv) to establish a sporadic AD model. A. jesdianum extract (100, 200, and 400 mg/kg/day) and donepezil (5 mg/kg/day) were orally administered for 14 days following model induction. Cognitive function was evaluated using the radial arm water maze test. Mitochondrial toxicity parameters in various brain regions (whole brain, frontal cortex, hippocampus, and cerebellum) were assessed. Gene expression analysis of miR-330, miR-132, Bax, and Bcl-2 in isolated rat brain neurons was performed using RT-qPCR. A. jesdianum extract significantly attenuated cognitive dysfunction and mitigated mitochondrial toxicity induced by icv-STZ administration. Following STZ injection, there was upregulation of Bax gene expression and downregulation of miR-330, miR-132, and Bcl-2 gene expression. Treatment with A. jesdianum extract resulted in the reversal of the expression of these microRNAs and genes, indicating its potential for improving AD and reducing neuronal apoptosis. This study demonstrates the neuroprotective capabilities of A. jesdianum against STZ-induced oxidative stress and cognitive impairment in rats, highlighting its therapeutic potential in the management of AD.

High-intensity interval training ameliorates Alzheimer's disease-like pathology by regulating astrocyte phenotype-associated AQP4 polarization

Background: Alzheimer's disease (AD), one of the most common forms of dementia, is a widely studied neurodegenerative disease characterized by Aβ accumulation and tau hyperphosphorylation. Currently, there is no effective cure available for AD. The astrocyte AQP4 polarized distribution-mediated glymphatic system is essential for Aβ and abnormal tau clearance and is a potential therapeutic target for AD. However, the role of exercise on the AQP4 polarized distribution and the association between the AQP4 polarized distribution and astrocyte phenotype polarization are poorly understood. Methods: Using a streptozotocin (STZ)-induced sporadic AD rat model, we investigated the effects of high-intensity interval training on AD pathologies. The Branes maze task was conducted to measure spatial learning and memory. Immunofluorescence staining of NeuN with TUNEL, Fluoro-Jade C, and relative neuronal damage markers was applied to measure neuronal apoptosis, neurodegeneration, and damage. Sholl analysis was carried out to analyze the morphology of microglia. Line-scan analysis, 3D rendering, and the orthogonal view were applied to analyze the colocalization. Western blot analysis and enzyme-linked immunosorbent assay (ELISA) analysis were conducted to examine AQP4 and Aβ, respectively. An APP/PS1 transgenic AD mice model was used to confirm the key findings. Results: High-intensity interval training (HIIT) alleviates cognitive dysfunction in STZ-induced AD-like rat models and provides neuroprotection against neurodegeneration, neuronal damage, and neuronal loss. Additionally, HIIT improved the drainage of abnormal tau and Aβ from the cortex and hippocampus via the glymphatic system to the kidney. Further mechanistic studies support that the beneficial effects of HIIT on AD might be due, in part, to the polarization of glial cells from a neurotoxic phenotype towards a neuroprotective phenotype. Furthermore, an intriguing finding of our study is that the polarized distribution of AQP4 was strongly correlated with astrocyte phenotype. We found A2 phenotype exhibited more evident AQP4 polarization than the A1 phenotype. Conclusion: Our findings indicate that HIIT ameliorates Alzheimer's disease-like pathology by regulating astrocyte phenotype and astrocyte phenotype-associated AQP4 polarization. These changes promote Aβ and p-tau clearance from the brain tissue through the glymphatic system and the kidney.

Effects of involuntary treadmill running in combination with swimming on adult neurogenesis in an Alzheimer's mouse model

Physical exercise plays a role on the prevention and treatment of Alzheimer's disease (AD), but the exercise mode and the mechanism for these positive effects is still ambiguous. Here, we investigated the effect of an aerobic interval exercise, running in combination with swimming, on behavioral dysfunction and associated adult neurogenesis in a mouse model of AD. We demonstrate that 4 weeks of the exercise could ameliorate Aβ₄₂ oligomer-induced cognitive impairment in mice utilizing Morris water maze tests. Additionally, the exercised Aβ₄₂ oligomer-induced mice exhibited a significant reduction of anxiety- and depression-like behaviors compared to the sedentary Aβ₄₂ oligomer-induced mice utilizing an Elevated zero maze and a Tail suspension test. Moreover, by utilizing 5'-bromodeoxyuridine (BrdU) as an exogenous cell tracer, we found that the exercised Aβ₄₂ oligomer-induced mice displayed a significant increase in newborn cells (BrdU⁺ cells), which differentiated into a majority of neurons (BrdU⁺ DCX⁺ cells or BrdU⁺NeuN⁺ cells) and a few of astrocytes (BrdU⁺GFAP⁺ cells). Likewise, the exercised Aβ₄₂ oligomer-induced mice also displayed the higher levels of NeuN, PSD95, synaptophysin, Bcl-2 and lower level of GFAP protein. Furthermore, alteration of serum metabolites in transgenic AD mice between the exercised and sedentary group were significantly associated with lipid metabolism, amino acid metabolism, and neurotransmitters. These findings suggest that combined aerobic interval exercise-mediated metabolites and proteins contributed to improving adult neurogenesis and behavioral performance after AD pathology, which might provide a promising therapeutic strategy for AD.

Combined effects of Aerobic exercise and 40Hz light flicker exposure on early cognitive impairments in Alzheimer's disease of 3xTg mice

Alzheimer's disease (AD) is a progressive degenerative brain disease and the primary cause of dementia. At an early stage, AD is generally characterized by short-term memory impairment, owing to dysfunctions of the cortex and hippocampus. We previously reported that a combination of exercise and 40 Hz light flickering can protect against AD-related neuroinflammation, gamma oscillations, reduction in Aβ, and cognitive decline. Therefore, we sought to extend our previous findings to the 5-month-old 3xTg-AD mouse model to examine whether the same favorable effects occur in earlier stages of cognitive dysfunction. We investigated the effects of 12 weeks of exercise combined with 40-Hz light flickering on cognitive function by analyzing neuroinflammation, mitochondrial function, and neuroplasticity in the hippocampus in a 3xTg-AD mouse model. 5-month-old 3xTg-AD mice performed 12 weeks of exercise with 40-Hz light flickering administered independently and in combination. Spatial learning and memory, long-term memory, hippocampal Aβ, tau, neuroinflammation, pro-inflammatory cytokine expression, mitochondrial function, and neuroplasticity, were analyzed. Aβ and tau proteins levels were significantly reduced in the early stage of AD, resulting in protection against cognitive decline by reducing neuroinflammation and pro-inflammatory cytokines. Furthermore, mitochondrial function improved, apoptosis was reduced, and synapse-related protein expression increased. Overall, exercise with 40-Hz light flickering was significantly more effective than exercise or 40-Hz light flickering alone, and the improvement was comparable to the levels in the non-transgenic aged-match control group. Our results indicate a synergistic effect of exercise and 40-Hz light flickering on pathological improvements in the hippocampus during early AD associated cognitive impairment.

The impact of moderate-intensity swimming exercise on learning and memory in aged rats: The role of Sirtuin-1

Objective(s):

The purpose of this study was to evaluate the effect of moderate-intensity swimming exercise on learning and memory by the Morris water maze test. Changes in the expressions of cyclic AMP-response element-binding protein (CREB) and brain-derived neurotrophic factor (BDNF) proteins alternative pathway which were activated by sirtuin-1 (SIRT-1) were investigated.

Materials and Methods:

The study included thirty-two male Sprague-Dawley rats (350-500 g, 11-12 and 15–16 months old). The rats were randomly divided into four groups with 8 rats in each group. The groups were designed as follows: Control-1 (11-12 months), Exercise-1 (11-12 months), Control-2 (15-16 months), Exercise-2 (15-16 months). Moderate-intensity exercise was assigned for 30 min/day, 5 days/week, for the whole training period of 8 weeks.

Results:

There were statistically significant differences between the groups on the third day (P=0.005) when swim speeds increased in the exercise groups. There was a statistically significant difference between Exercise 1 and Exercise 2 groups, the entries in the platform zone decreased in Exercise 2 group (P=0.026). While there were no histopathological findings observed in any group, increased SIRT-1, BNDF, and CREB expressions were seen in exercise groups compared with control groups.

Conclusion:

In aged rats exercising at moderate intensity, increased expression of CREB and BDNF, and SIRT-1 could improve hippocampal-dependent memory.

Resistance Exercise Improves Spatial Learning Ability Through Phosphorylation of 5'-Adenosine Monophosphate-Activated Protein Kinase in Parkinson Disease Mice

Purpose

Exercise is a representative noninvasive treatment that can be applied to various diseases. We studied the effect of resistance exercise on motor function and spatial learning ability in Parkinson disease (PD) mice.

Methods

The rotarod test and beam walking test were conducted to evaluate the effect of resistance exercise on motor function, and the Morris water maze test was conducted to examine the effect of resistance exercise on spatial learning ability. The effect of resistance exercise on brain-derived neurotrophic factor (BDNF) and tropomyosin receptor kinase B (TrkB) expression and 5’-adenosine monophosphate-activated protein kinase (AMPK) phosphorylation was investigated by Western blot analysis. New cell generation was confirmed by immunohistochemistry for 5-bromo-2’-deoxyuridine.

Results

Resistance exercise improved coordination, balance, and spatial learning ability in PD mice. Resistance exercise enhanced new cell production, BDNF and TrkB expression, and AMPK phosphorylation in PD mice. The effect of such resistance exercise was similar to that of levodopa application.

Conclusions

In PD-induced mice, resistance exercise enhanced AMPK phosphorylation to increase BDNF expression and new neuron generation, thereby improving spatial learning ability. Resistance exercise is believed to help improve symptoms of PD.

Neuroprotective mechanisms of chronic physical exercise via reduction of β-amyloid protein in experimental models of Alzheimer's disease: A systematic review

AIMS

Alzheimer's disease (AD) is the most common irreversible chronic neurodegenerative disease. It is characterized by the abnormal accumulation of β-amyloid protein (Aβ), which triggers homeostatic breakage in several physiological systems. However, the effect of chronic exercise on the formation of Aβ as an alternative therapy has been investigated. This systematic review examines the antiamyloid effect of different types and intensities of exercise, seeking to elucidate its neuroprotective mechanisms.

MAIN METHODS

The research was conducted in the electronic databases Pubmed, Embase, Scopus and Web of Science, using the following descriptors: "amyloid beta" (OR senile plaque OR amyloid plaque) and "exercise" (OR physical activity OR training). The risk of bias was evaluated through SYRCLE's Risk of Bias for experimental studies.

KEY FINDINGS

2268 articles were found, being 36 included in the study. A higher frequency of use of mice with genetic alterations was identified for the Alzheimer's disease (AD) model (n = 29). It was used as chronic training: treadmill running (n = 24), voluntary running wheel (n = 7), swimming (n = 4) and climbing (n = 2). The hippocampus and the cortex were the most investigated regions. However, physiological changes accompanied by the reduction of Aβ and associated with AD progression were verified. It is concluded that exercise reduces the production of Aβ in models of animals with AD.

SIGNIFICANCE

Nevertheless, this effect contributes to the improvement of several physiological aspects related to Aβ and that contribute to neurological impairment in AD.

An 8-Week Administration of Bifidobacterium bifidum and Lactobacillus plantarum Combined with Exercise Training Alleviates Neurotoxicity of Aβ and Spatial Learning via Acetylcholine in Alzheimer Rat Model

This study aimed to determine the effects of 8 weeks of an administration of Bifidobacterium bifidum and Lactobacillus plantarum combined with exercise training on neurotoxicity of Aβ, spatial learning, acetylcholine (ACH), and vascular endothelial growth factor (VEGF) in Alzheimer rats. Twenty-five Wistar rats were randomly divided into 5 groups (n = 5 in each): (1) healthy control (control), (2) Alzheimer disease (AD), (3) AD with treadmill exercise (AD + Exe), (4) AD with probiotic (combined administration of Bifidobacterium bifidum and Lactobacillus plantarum) treatment (AD + Pro), and (5) AD with treadmill exercise and probiotic treatment (AD + Exe + Pro). AD was induced by intra-cerebroventricular injection of Aβ1-42 peptide. Then, the training groups exercised on treadmill for 8 weeks, 5 days per weeks. The rats were treated daily with probiotic supplements via gavage for 8 weeks. The Morris water maze (MWM) test was administered to measure spatial learning. Then, the animals were sacrificed and Vegf and ACH were analyzed using the qPCR and immunohistochemistry (IHC) methods, respectively. Results showed that the β-amyloid plaques were significantly increased in the brains of the AD group compared with the control group (p < 0.001). The combined use of probiotics and exercise training significantly increased the time spent in the target quadrant after removing the platform, compared with the AD group in the Morris water maze test (p < 0.001). Crystal violet analysis showed that sole (p < 0.01) and combined exercise training and probiotic supplementation (p < 0.001) significantly reduced the number of dead cells in the brains of rats compared with the AD group. AD significantly decreased Vegf mRNA and ACH in the CA1 area of the hippocampus (p < 0.001). However, mono and combined therapy (exercise and probiotics) significantly increased ACH in the rats' brain compared with the AD group. Overall, 8 weeks of an administration of Bifidobacterium bifidum and Lactobacillus plantarum combined with exercise training can improve spatial learning impairment in the AD rats. Exercise and probiotics seem to offer potential benefits to AD patients by upregulating ACH.

Critical Review of the Alzheimer's Disease Non-Transgenic Models: Can They Contribute to Disease Treatment?

Alzheimer's disease (AD) is a growing neurodegenerative disease without effective treatments or therapies. Despite the use of different approaches and an extensive variety of genetic amyloid based models, therapeutic strategies remain elusive. AD is characterized by three main pathological hallmarks that include amyloid-β plaques, neurofibrillary tangles, and neuroinflammatory processes; however, many other pathological mechanisms have been described in the literature. Nonetheless, the study of the disease and the screening of potential therapies is heavily weighted toward the study of amyloid-β transgenic models. Non-transgenic models may aid in the study of complex pathological states and provide a suitable complementary alternative to evaluating therapeutic biomedical and intervention strategies. In this review, we evaluate the literature on non-transgenic alternatives, focusing on the use of these models for testing therapeutic strategies, and assess their contribution to understanding AD. This review aims to underscore the need for a shift in preclinical research on intervention strategies for AD from amyloid-based to alternative, complementary non-amyloid approaches.

Postnatal alcohol exposure and adolescent exercise have opposite effects on cerebellar microglia in rat

Developmental alcohol exposure results in altered neuroimmune function in both humans and rodents. Given the critical role for the principle neuroimmune cell, microglia, in maintaining synaptic form and function, microglial dysfunction in the cerebellum may be an important mechanism underlying the aberrant cerebellar connectivity observed in rodent models of fetal alcohol spectrum disorders. Using an established rodent model of alcohol exposure during human third-trimester fetal development, we examine the cerebellum of male and female Long Evans rats to determine the impact of early postnatal alcohol exposure on cerebellar microglia, and the potential therapeutic effects of an adolescent intervention consisting of voluntary exercise (running). All cerebelli were examined at postnatal day 42 (i.e., late adolescence), and microglia were labeled with Iba1, a microglia-specific protein. Early postnatal alcohol exposure caused an increase in microglial density throughout cerebellum and a reduction in cerebellar volume, and a reduction in the proportion of fully ramified (often called "resting state") microglia selective to lobules 1-4. In contrast, adolescent exercise decreased microglial density throughout cerebellum and increased cerebellar volume, while activating microglia (as indicated by increases in amoeboid microglia, and reductions in fully and partially ramified microglia) selectively in lobules 1-4. These results suggest that adolescent exercise may be a suitable intervention to ameliorate alcohol-induced neuroimmune dysfunction as it alters microglia density and cerebellar volume in opposite to the effects of developmental alcohol exposure. Importantly, exercise intervention can be flexibly implemented well after the time window of vulnerability to alcohol.

Impact of exercise on hippocampal neurogenesis in hyperglycemic diabetes

Hyperglycemic diabetes is a chronic metabolic disorder characterized by high level of plasma glucose. Numerous studies have shown that hy-perglycemic diabetes leads to brain dysfunction including cognitive im-pairment and emotional disorders. This study evaluated the impact of exercise on brain dysfunction, hippocampal neurogenesis, and cogni-tive impairment in hyperglycemic diabetes. The present study suggests that exercise improves hyperglycemic control and prevents decline of cognition through increasing hippocampal neurogenesis. Understanding the mechanism of exercise for hippocampal neurogenesis can lead to the development of therapeutic strategies for metabolic disorders.

Polydeoxyribonucleotide Exerts Therapeutic Effect by Increasing VEGF and Inhibiting Inflammatory Cytokines in Ischemic Colitis Rats

Ischemic colitis is resulted from an inadequate blood supply to a segment or entire colon. Polydeoxyribonucleotide (PDRN), extracted from salmon sperm, has been reported to exert anti-inflammatory and anti-ischemic effects through the adenosine A_2A receptor (A_2AR). We investigated whether PDRN possesses therapeutic effectiveness on ischemic colitis rats. Ischemic colitis was induced by selective devascularization. The skin temperature on the ischemic colitis-induced region was determined. To assess the colonic damage score and collagen deposition, colonic tissue sections were stained with hematoxylin and eosin (H&E), and Masson trichrome staining was performed. Western blot analysis for A_2AR, vascular endothelial growth factor (VEGF), cyclooxygenase-2 (COX-2), tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and IL-6, Bax, Bcl-2, and extracellular signal-regulated kinase 1/2 (ERK1/2) was performed. Skin temperature was increased and mucosal damage and collagen deposition were observed in the affected colonic tissues in the ischemic colitis rats. Expressions of inflammatory cytokines (TNF-α, IL-1β, and IL-6) and inflammatory mediator (COX-2) were upregulated in the ischemic colitis rats. Apoptosis was increased by decreasing the ratio of Bcl-2 to Bax and by suppressing the phosphorylated form of ERK1/2 expression in the ischemic colitis rats. Treatment with PDRN alleviated mucosal damage reduced the expressions of inflammatory cytokines and COX-2 and inhibited apoptosis in the ischemic colitis rats. PDRN treatment more enhanced the expressions of A_2AR and VEGF in the ischemic colitis rats. PDRN showed therapeutic effectiveness on ischemic colitis by increasing VEGF expression and inhibiting inflammatory cytokines and COX-2 through enhancing A_2AR expression.

Treadmill Exercise Suppresses Cognitive Decline and Increases White Matter Oligodendrocyte Precursor Cells in a Mouse Model of Prolonged Cerebral Hypoperfusion

Clinical evidence suggests that patients with subcortical ischemic vascular dementia (SIVD) perform better at cognitive tests after exercise. However, the underlying mechanism for this effect is largely unknown. Here, we examined how treadmill exercise changes the cognitive function and white matter cellular pathology in a mouse model of SIVD. Prolonged cerebral hypoperfusion was induced in 2-month-old male C57BL/6J mice by bilateral common carotid artery stenosis. A week later, the mice were randomly divided into a group that received 6-week treadmill exercise and a sedentary group for observation. In multiple behavioral tests (Y-maze, novel object recognition, and Morris water maze tests), the treadmill exercise training was shown to ameliorate cognitive decline in the hypoperfused SIVD mice. In addition, immunohistological analyses confirmed that there was a larger population of oligodendrocyte precursor cells in the subventricular zone of exercised versus sedentary mice. Although further investigations are needed to confirm a causal link between these findings, our study establishes a model and cellular foundation for investigating the mechanisms through which exercise preserves cognitive function in SIVD.

G, Calderon O, Moreno-Gonzalez I. Modifiable Risk Factors for Alzheimer's Disease

Since first described in the early 1900s, Alzheimer's disease (AD) has risen exponentially in prevalence and concern. Research still drives to understand the etiology and pathogenesis of this disease and what risk factors can attribute to AD. With a majority of AD cases being of sporadic origin, the increasing exponential growth of an aged population and a lack of treatment, it is imperative to discover an easy accessible preventative method for AD. Some risk factors can increase the propensity of AD such as aging, sex, and genetics. Moreover, there are also modifiable risk factors-in terms of treatable medical conditions and lifestyle choices-that play a role in developing AD. These risk factors have their own biological mechanisms that may contribute to AD etiology and pathological consequences. In this review article, we will discuss modifiable risk factors and discuss the current literature of how each of these factors interplay into AD development and progression and if strategically analyzed and treated, could aid in protection against this neurodegenerative disease.

Iron Exposure and the Cellular Mechanisms Linked to Neuron Degeneration in Adult Mice

Although the causal relationship between Alzheimer's disease (AD) and iron overload remains unclear, iron dyshomeostasis or improper transport mechanisms are speculated to lead to the accumulation of this neurotoxic metal in the hippocampal formation and other cerebral areas related to neurodegenerative diseases, resulting in the formation of reactive oxygen species (ROS) and, ultimately, cell death. In this study, exposure to high dietary iron (HDI) revealed no significant difference in the number of iron-positive cells and iron content in the cortex and hippocampal region between wild-type (WT) and APP/PS1 mice; however, compared with the control mice, the HDI-treated mice exhibited upregulated divalent metal transporter 1 (DMT1) and ferroportin (Fpn) expression, and downregulated transferrin receptor (TFR) expression. Importantly, we confirmed that there were significantly fewer NeuN-positive neurons in both APP/PS1 and WT mice given HDI, than in the respective controls. Moreover, this iron-induced neuron loss may involve increased ROS and oxidative mitochondria dysfunction, decreased DNA repair, and exacerbated apoptosis and autophagy. Although HDI administration might trigger protective antioxidant, anti-apoptosis, and autophagy signaling, especially in pathological conditions, these data clearly indicate that chronic iron exposure results in neuronal loss due to apoptosis, autophagy, and ferroptosis, hence increasing the risk for developing AD.

Probiotic mixture of Lactobacillus helveticus R0052 and Bifidobacterium longum R0175 attenuates hippocampal apoptosis induced by lipopolysaccharide in rats

In recent years, the beneficial impact of targeted gut microbiota manipulation in various neurological disorders has become more evident. Therefore, probiotics have been considered as a promising approach to modulate brain gene expression and neuronal pathways even in some neurodegenerative diseases. The purpose of this study was to determine the effect of probiotic biotherapy with combination of Lactobacillus helveticus R0052 and Bifidobacterium longum R0175 on the expression levels of proteins critical to neuronal apoptosis in hippocampus of lipopolysaccharide (LPS)-exposed rats. Four groups of animals (Control, LPS, Probiotic + LPS, and Probiotic) were treated with maltodextrin (placebo) or probiotic (10⁹ CFU/ml/rat) for 2 weeks by gavage. On the 15th day, a single intraperitoneal dose of saline or LPS (1 mg/kg) was injected and 4 h later, protein assessment was performed by western blotting in hippocampal tissues. LPS significantly increased the Bax, Bax/Bcl-2 ratio, and cleaved caspase-3 expression along with decreased the Bcl-2 and procaspase-3 protein levels. However, probiotic pretreatment (L. helveticus R0052 + B. longum R0175) significantly downregulated the Bax and Bax/Bcl-2 ratio accompanied with upregulated Bcl-2 expression. Prophylactic treatment with these bacteria also attenuated LPS-induced caspase-3 activation by remarkably increasing the expression of procaspase-3 while reducing the level of cleaved caspase-3 in target tissues. Our data indicate that probiotic formulation (L. helveticus R0052 + B. longum R0175) alleviated hippocampal apoptosis induced by LPS in rats via the gut-brain axis and suggest that this probiotic could play a beneficial role in some neurodegenerative conditions.

PI3K-Akt-Wnt Pathway Is Implicated in Exercise-Induced Improvement of Short-term Memory in Cerebral Palsy Rats

PURPOSE

Maternal lipopolysaccharide (LPS) injection induces neurodevelopmental disorders, such as cerebral palsy. Exercise activates phosphatidylinositol 3-kinase (PI3K)-protein kinase B (Akt) signaling pathway that enhances neurogenesis. Wnt ligands are also implicated in the hippocampal neurogenesis and synaptic plasticity. Glycogen synthase kinase-3β (GSK-3β) is a downstream molecule of Akt, and GSK-3β is known to modulate hippocampal neurogenesis negatively.

METHODS

Cerebral palsy was made by maternal LPS-injection. On the 5 weeks after birth, treadmill running was applied to the rat pups of the exercise groups, for 30 minutes, 5 times a week during 6 weeks.

RESULTS

Treadmill running alleviated short-term memory impairments of the cerebral palsy rat pups. Hippocampal cell proliferation was increased and hippocampal apoptosis was suppressed by treadmill running in the cerebral palsy rat pups. Hippocampal phosphorylated-PI3K/PI3K ratio, phosphorylated-Akt/Akt ratio, and Wnt expression were enhanced by treadmill running in the cerebral palsy rat pups. In contrast, hippocampal phosphorylated-GSK-3β/GSK-3β ratio and β-catenin expression were suppressed by treadmill running in the cerebral palsy rat pups.

CONCLUSION

The results of this study showed that short-term memory improvement due to treadmill running in cerebral palsy occurs via activation of the PI3K-Akt-Wnt pathway.

Treadmill exercise improves memory function by inhibiting hippocampal apoptosis in pilocarpine-induced epileptic rats

Epilepsy is characterized by recurrent seizures and loss of neurons with abnormal rhythmic firing in the brains. In the present study, we investigated the effect of treadmill exercise on memory function in relation with cell proliferation and apoptosis in the hippocampus using pilocarpine-induced seizure rats. Epilepsy was initiated by intraperitoneal injection of pilocarpine hydrochloride. The rats in the exercise group were forced to run on a motorized treadmill for 30 min once a day for 2 weeks. In the present results, treadmill exercise alleviated short-term and spatial learning memory impairments in the epileptic rats. Treadmill exercise suppressed neuronal degeneration and enhanced neuronal maturation in the epileptic rats. Treadmill exercise suppressed cell proliferation and apoptosis in the epileptic rats. Treadmill exercise alleviated pilocarpine-induced memory impairments and suppressed neuronal loss in the hippocampus through down-regulation of apoptosis. These findings offer a possibility that treadmill exercise may provide a preventive or therapeutic value to the epilepsy-induced learning and memory impairments.

Treadmill Exercise Improves Motor Function by Suppressing Purkinje Cell Loss in Parkinson Disease Rats

PURPOSE

Rotenone is the most widely used neurotoxin for the making Parkinson disease (PD) animal model. The neurodegenerative disorder PD shows symptoms, such as slowness of movements, tremor at resting, rigidity, disturbance of gait, and instability of posture. We investigated whether treadmill running improves motor ability using rotenone-caused PD rats. The effect of treadmill running on PD was also assessed in relation with apoptosis of cerebellar Purkinje cells.

METHODS

Treadmill running was applied to the rats in the exercise groups for 30 minutes once a day for 4 weeks, starting 4 weeks after birth. We used rota-rod test for the determination of motor coordination and balance. In this experiment, terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) staining, immunohistochemistry for calbindin, glial fibrillary acidic protein (GFAP), Iba-1, and western blot analysis for Bax and Bcl-2 were performed.

RESULTS

Treadmill running enhanced motor balance and coordination by preventing the loss of Purkinje cells in the cerebellar vermis. Treadmill running suppressed PD-induced expression of GFAP-positive reactive astrocytes and Iba-1-positive microglia, showing that treadmill running suppressed reactive astrogliosis and microglia activation. Treadmill running suppressed TUNEL-positive cell number and Bax expression and enhanced Bcl-2 expression, demonstrating that treadmill running inhibited the progress of apoptosis in the cerebellum of rotenone-induced PD rats.

CONCLUSION

Treadmill running improved motor ability of the rotenone-induced PD rats by inhibiting apoptosis in the cerebellum. Apoptosis suppressing effect of treadmill running on rotenone-induced PD was achieved via suppression of reactive astrocyte and inhibition of microglial activation.

Depression and adult neurogenesis: Positive effects of the antidepressant fluoxetine and of physical exercise

Of wide interest for health is the relation existing between depression, a very common psychological illness, accompanied by anxiety and reduced ability to concentrate, and adult neurogenesis. We will focus on two neurogenic stimuli, fluoxetine and physical exercise, both endowed with the ability to activate adult neurogenesis in the dentate gyrus of the hippocampus, known to be required for learning and memory, and both able to counteract depression. Fluoxetine belongs to the class of selective serotonin reuptake inhibitor (SSRI) antidepressants, which represent the most used pharmacological therapy; physical exercise has also been shown to effectively counteract depression symptoms in rodents as well as in humans. While there is evidence that the antidepressant effect of fluoxetine requires its pro-neurogenic action, exerted by promoting proliferation, differentiation and survival of progenitor cells of the hippocampus, on the other hand fluoxetine exerts also neurogenesis-independent antidepressant effects by influencing the plasticity of the new neurons generated. Similarly, the antidepressant action of running also correlates with an increase of hippocampal neurogenesis and plasticity, although the gene pathways involved are only partially coincident with those of fluoxetine, such as those involved in serotonin metabolism and synapse formation. We further discuss how extra-neurogenic actions are also suggested by the fact that, unlike running, fluoxetine is unable to stimulate neurogenesis during aging, but still displays antidepressant effects. Moreover, in specific conditions, fluoxetine or running activate not only progenitor but also stem cells, which normally are not stimulated; this fact reveals how stem cells have a long-term, hidden ability to self-renew and, more generally, that neurogenesis is subject to complex controls that may play a role in depression, such as the type of neurogenic stimulus or the state of the local niche. Finally, we discuss how fluoxetine or running are effective in counteracting depression originated from stress or neurodegenerative diseases.

Molecular Mechanisms of Oligodendrocyte Regeneration in White Matter-Related Diseases

Even in adult brains, restorative mechanisms are still retained to maintain the microenvironment. Under the pathological conditions of central nervous system (CNS) diseases, several immature cells in the brain would be activated as a compensative response. As the concept of the neurovascular unit emphasizes, cell-cell interactions play important roles in this restorative process. White matter damage and oligodendrocyte loss are representative characteristics for many neurodegenerative diseases. In response to oligodendrocyte damage, residual oligodendrocyte precursor cells (OPCs) initiate their proliferation and differentiation for the purpose of remyelination. Although mechanisms of oligodendrogenesis and remyelination in CNS diseases are still mostly unknown and understudied, accumulated evidence now suggests that support from neighboring cells is necessary for OPC proliferation and differentiation. In this review, we first overview basic mechanisms of interaction between oligodendrocyte lineage cells and neighboring cells, and then introduce how oligodendrogenesis occurs under the conditions of neurodegenerative diseases, focusing on vascular cognitive impairment syndrome, Alzheimer’s disease, and multiple sclerosis.

Memorcise and Alzheimer's disease

Alzheimer's disease (AD) is a debilitating disease influencing a multitude of outcomes, including memory function. Recent work suggests that memory may be influenced by exercise ('memorcise'), even among those with AD. The present narrative review details (1) the underlying mechanisms of AD; (2) whether exercise has a protective effect in preventing AD; (3) the mechanisms through which exercise may help to prevent AD; (4) the mechanisms through which exercise may help attenuate the progression of AD severity among those with existing AD; (5) the effects and mechanisms through which exercise is associated with memory among those with existing AD; and (6) exercise recommendations for those with existing AD. Such an understanding will aid clinicians in their ability to use exercise as a potential behavioral strategy to help prevent and treat AD.

Effect of treadmill exercise on spatial navigation impairment associated with cerebellar Purkinje cell loss following chronic cerebral hypoperfusion

In addition to roles in motor coordination, the cerebellum is also associated with cognitive function. The aim of the present study was to investigate the effect of treadmill exercise on spatial navigation deficit induced by chronic cerebral hypoperfusion (CCH). Furthermore, whether decreased loss of Purkinje cells, which contain the calcium-binding protein in the posterior lobe of the cerebellum, attenuates the spatial navigation deficit induced by CCH was also investigated. Wistar rats were randomly divided into three groups: Sham group, bilateral common carotid arteries occlusion (BCCAO) group and a BCCAO + exercise (Ex) group. The rats in the BCCAO + Ex group ran on a treadmill for 30 min once a day for 8 weeks, starting at 4 weeks post-birth. CCH was induced by performing BCCAO at 12 weeks post-birth. The Morris water maze test was performed to determine the spatial navigation function of the rats. To investigate the histological features of the cerebellum in all of the experimental groups post-treatment, terminal deoxynucleotidyl transferase dUTP nick end labeling staining, as well as immunohistochemical analysis revealing the expression of calbindin, parvalbumin, glial fibrillary acidic protein, ionized calcium-binding adaptor molecule 1 and caspase-3, was performed. The results of the present study revealed that treadmill exercise improved spatial navigation, decreased the expression of reactive astrocytes and microglial cells, and decreased apoptotic rates in the cerebellar vermis post-CCH. Treadmill exercise also attenuated the loss of Purkinje cells following CCH. The number of Purkinje cells was revealed to be negatively correlated with spatial navigation performance. These results indicate that treadmill exercise may attenuate spatial navigation impairment via inhibition of Purkinje cell loss in the posterior lobe of the cerebellum following CCH. Therefore, treadmill exercise may represent a therapeutic strategy for the treatment of patients with spatial navigation impairment following CCH.

Physical exercise promotes memory capability by enhancing hippocampal mitochondrial functions and inhibiting apoptosis in obesity-induced insulin resistance by high fat diet

A high-fat diet induces obesity in mice, leading to insulin resistance, decreased mitochondrial function, and increased apoptosis in the hippocampus, which eventually result in memory loss. The present study investigated the effect of physical exercise on memory, hippocampal mitochondrial function, and apoptosis in mice with in insulin resistance caused by obesity due to high-fat diet. Mice were randomly divided into four groups: control (CON), control and exercise (CON + EX), high fat diet (HFD), and high fat diet and exercise (HFD + EX). After receiving a high-fat (60%) diet for 20 weeks to induce obesity, the animals were subjected to an exercise routine 6 times per week, for 12 weeks. The exercise duration and intensity gradually increased over 4-week intervals. Hippocampal memory was examined using the step-down avoidance task. Mitochondrial function and apoptosis were also examined in the hippocampus and dentate gyrus. We found that obesity owing to a high-fat diet induced insulin resistance and caused a decrease in memory function. Insulin resistance also caused a decrease in mitochondrial function in the hippocampus by reducing Ca²⁺ retention and O_2, respiration, increasing the levels of H₂O₂, and Cyp-D, and mPTP opening. In addition, apoptosis in the hippocampus increased owing to decreased expression of Bcl-2 and increased expression of Bax, cytochrome c, and caspase-3 and TUNEL-positive cells. In contrast, physical exercise led to reduced insulin resistance, improved mitochondrial function, and reduced apoptosis in the hippocampus. The results suggest that physiological stimulations such as exercise improve hippocampal function and suppress apoptosis, potentially preventing the memory loss associated with obesity-induced insulin resistance.

Review: Impact of Helicobacter pylori on Alzheimer's disease: What do we know so far?

BACKGROUND

Helicobacter pylori has changed radically gastroenterologic world, offering a new concept in patients' management. Over time, more medical data gave rise to diverse distant, extragastric manifestations and interactions of the "new" discovered bacterium. Special interest appeared within the field of neurodegenerative diseases and particularly Alzheimer's disease, as the latter and Helicobacter pylori infection are associated with a large public health burden and Alzheimer's disease ranks as the leading cause of disability. However, the relationship between Helicobacter pylori infection and Alzheimer's disease remains uncertain.

METHODS

We performed a narrative review regarding a possible connection between Helicobacter pylori and Alzheimer's disease. All accessible relevant (pre)clinical studies written in English were included. Both affected pathologies were briefly analyzed, and relevant studies are discussed, trying to focus on the possible pathogenetic role of this bacterium in Alzheimer's disease.

RESULTS

Data stemming from both epidemiologic studies and animal experiments seem to be rather encouraging, tending to confirm the hypothesis that Helicobacter pylori infection might influence the course of Alzheimer's disease pleiotropically. Possible main mechanisms may include the bacterium's access to the brain via the oral-nasal-olfactory pathway or by circulating monocytes (infected with Helicobacter pylori due to defective autophagy) through disrupted blood-brain barrier, thereby possibly triggering neurodegeneration.

CONCLUSIONS

Current data suggest that Helicobacter pylori infection might influence the pathophysiology of Alzheimer's disease. However, further large-scale randomized controlled trials are mandatory to clarify a possible favorable effect of Helicobacter pylori eradication on Alzheimer's disease pathophysiology, before the recommendation of short-term and cost-effective therapeutic regimens against Helicobacter pylori-related Alzheimer's disease.

Heme Oxygenase-1 Activity as a Correlate to Exercise-Mediated Amelioration of Cognitive Decline and Neuropathological Alterations in an Aging Rat Model of Dementia

Alzheimer's disease (AD) is a neurodegenerative disorder with cognitive impairment. Physical exercise has long been proven to be beneficial in the disorder. The present study was designed to examine the effect of voluntary exercise on spatial memory, imaging, and pathological abnormalities. Particular focus has been given to the role of heme oxygenase-1 (HO-1)—an important cellular cytoprotectant in preserving mental acuity—using an aging rat model of dementia. Male and female Wistar rats were segregated into six groups—namely, (i) aged sedentary (control) females (ASF, n = 8); (ii) aged sedentary (control) males (ASM, n = 8); (iii) aged running females (ARF, n = 8); (iv) aged running males (ARM, n = 8); (v) young control females (YCF, n = 8); and (vi) young control males (YCM, n = 8). Rats in the ARF and ARM groups had free access to a standardized inbuilt running wheel during the 3-month evaluation period. Spatial memory was investigated using the Morris Water Test, imaging and pathological alterations were assessed using positron emission tomography (PET) imaging and histopathological examinations (H&E, Congo red staining), respectively, and HO-1 enzyme activity assays were also conducted. The outcomes suggest that voluntary physical exercise mitigates impaired spatial memory and neuropathological changes exhibited by the aging sedentary group, via elevated HO-1 activity, contributing to the antioxidant capacity in the aging brain.

Dexmedetomidine Oral Mucosa Patch for Sedation Suppresses Apoptosis in Hippocampus of Normal Rats

Purpose

Dexmedetomidine, an α2-adrenergic agonist, provides sedative and analgesic effects without significant respiratory depression. Dexmedetomidine has been suggested to have an antiapoptotic effect in response to various brain insults. We developed an oral mucosa patch using dexmedetomidine for sedation. The effects of the dexmedetomidine oral mucosa patch on cell proliferation and apoptosis in the hippocampus were evaluated.

Methods

A hydrogel oral mucosa patch was adhered onto the oral cavity of physiologically normal rats, and was attached for 2 hours, 6 hours, 12 hours, or 24 hours. Plasma dexmedetomidine concentrations were determined by liquid chromatography– electrospray ionization–tandem mass spectrometry–multiple-ion reaction monitoring (LC-ESI-MS/MS-MRM). Cell proliferation in the hippocampus was detected by Ki-67 immunohistochemistry. Caspase-3 immunohistochemistry, terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling staining, and Western blotting for Bax and Bcl-2 were performed to detect hippocampal apoptosis. The levels of brain-derived neurotrophic factor (BDNF) and tyrosine kinase B (TrkB) in the hippocampus were also measured by Western blotting.

Results

Plasma dexmedetomidine concentration increased according to the attachment time of the dexmedetomidine oral mucosa patch. Hippocampal cell proliferation did not change due to the dexmedetomidine oral mucosa patch, and the dexmedetomidine oral mucosa patch exerted no significant effect on BDNF or TrkB expression. In contrast, the dexmedetomidine oral mucosa patch exerted an antiapoptotic effect depending on the attachment time of the dexmedetomidine oral mucosa patch.

Conclusions

A dexmedetomidine oral mucosa patch can be used as a convenient tool for sedation, and is of therapeutic value due to its antiapoptotic effects under normal conditions.