Preischemic treadmill exercise improves short-term memory by inhibiting hypoperfusion-induced disruption of blood-brain barrier after bilateral common carotid arteries occlusion

Research progress on the mechanism and markers of metabolic disorders in the occurrence and development of cognitive dysfunction after ischemic stroke

Post-stroke cognitive impairment (PSCI) is a common complication following a stroke that significantly affects patients' quality of life and rehabilitation outcomes. It also imposes a heavy economic burden. There is an urgent need to better understand the pathophysiology and pathogenesis of PSCI, as well as to identify markers that can predict PSCI early in the clinical stage, facilitating early prevention, monitoring, and treatment. Although the mechanisms underlying PSCI are complex and multifaceted, involving factors such as atherosclerosis and neuroinflammation, metabolic disorders also play a critical role. This article primarily reviews the relationship between metabolic disorders of the three major nutrients-sugar, fat, and protein-and the development of cognitive dysfunction following ischemic stroke (IS). It aims to elucidate how these metabolic disturbances contribute to cognitive dysfunction post-stroke and to explore potential metabolic biomarkers for PSCI. We believe that this review will offer new insights into the early identification, treatment, and prognostic assessment of PSCI.

Exploring the neuroprotective role of physical activity in cerebral small vessel disease

Cerebral small vessel disease (cSVD) is a common neurological finding characterized by abnormalities of the small blood vessels in the brain. Previous research has established a strong connection between cSVD and stroke, as well as neurodegenerative disorders, notably Alzheimer's disease (AD) and other dementias. As the search for effective interventions continues, physical activity (PA) has emerged as a potential preventative and therapeutic avenue. This review synthesizes the human and animal literature on the influence of PA on cSVD, highlighting the importance of determining optimal exercise protocols, considering aspects such as intensity, duration, timing, and exercise type. Furthermore, the necessity of widening the age bracket in research samples is discussed, ensuring a holistic understanding of the interventions across varying pathological stages of the disease. The review also suggests the potential of exploring diverse biomarkers and risk profiles associated with clinically significant outcomes. Moreover, we review findings demonstrating the beneficial effects of PA in various rodent models of cSVD, which have uncovered numerous mechanisms of neuroprotection, including increases in neuroplasticity and integrity of the vasculature and white matter; decreases in inflammation, oxidative stress, and mitochondrial dysfunction; and alterations in amyloid processing and neurotransmitter signaling. In conclusion, this review highlights the potential of physical activity as a preventive strategy for addressing cSVD, offering insights into the need for refining exercise parameters, diversifying research populations, and exploring novel biomarkers, while shedding light on the intricate mechanisms through which exercise confers neuroprotection in both humans and animal models.

Exercise before pregnancy exerts protective effect on prenatal stress-induced impairment of memory, neurogenesis, and mitochondrial function in offspring

Stress during pregnancy has a negative effect on the fetus. However, maternal exercise has a positive effect on the cognitive function of the fetus and alleviates the negative effects of stress. This study aimed to demonstrate whether exercise before pregnancy has a protective effect on prenatal stress-induced impairment of memory, neurogenesis and mitochondrial function in mice offspring. In this experiment, immunohistochemistry, Western blot, measurement of mitochondria oxygen respiration, and behavior tests were performed. Spatial memory and short-term memory of the offspring from the prenatal stress with exercise were increased compared to the offspring from the prenatal stress. The numbers of doublecortin-positive and 5-bromo-2'-deoxyuridine-positive cells in the hippocampal dentate gyrus of the offspring from the prenatal stress with exercise were higher compared to the offspring from the prenatal stress. The expressions of brain-derived neurotrophic factor, postsynaptic density 95 kDa, and synaptophysin in the hippocampus of the offspring from the prenatal stress with exercise were enhanced compared to the offspring from the prenatal stress. Oxygen consumption of the offspring from the prenatal stress with exercise were higher compared to the offspring from the prenatal stress. Exercise before pregnancy alleviated prenatal stress-induced impairment of memory, neurogenesis, and mitochondrial function. Therefore, exercise before pregnancy may have a protective effect against prenatal stress of the offspring.

Lipopolysaccharide-Induced Delirium-like Behaviour in a Rat Model of Chronic Cerebral Hypoperfusion Is Associated with Increased Indoleamine 2,3-Dioxygenase Expression and Endotoxin Tolerance

Indoleamine 2,3-dioxygenase (IDO) and the tryptophan-kynurenine pathway (TRP-KP) are upregulated in ageing and could be implicated in the pathogenesis of delirium. This study evaluated the role of IDO/KP in lipopolysaccharide (LPS)-induced delirium in an animal model of chronic cerebral hypoperfusion (CCH), a proposed model for delirium. CCH was induced by a permanent bilateral common carotid artery ligation (BCCAL) in Sprague Dawley rats to trigger chronic neuroinflammation-induced neurodegeneration. Eight weeks after permanent BCCAL, the rats were treated with a single systemic LPS. The rats were divided into three groups: (1) post-BCCAL rats treated with intraperitoneal (i.p.) saline, (2) post-BCCAL rats treated with i.p. LPS 100 μg/kg, and (3) sham-operated rats treated with i.p. LPS 100 μg/kg. Each group consisted of 10 male rats. To elucidate the LPS-induced delirium-like behaviour, natural and learned behaviour changes were assessed by a buried food test (BFT), open field test (OFT), and Y-maze test at 0, 24-, 48-, and 72 h after LPS treatment. Serum was collected after each session of behavioural assessment. The rats were euthanised after the last serum collection, and the hippocampi and cerebral cortex were collected. The TRP-KP neuroactive metabolites were measured in both serum and brain tissues using ELISA. Our data show that LPS treatment in CCH rats was associated with acute, transient, and fluctuated deficits in natural and learned behaviour, consistent with features of delirium. These behaviour deficits were mild compared to the sham-operated rats, which exhibited robust behaviour impairments. Additionally, heightened hippocampal IDO expression in the LPS-treated CCH rats was associated with reduced serum KP activity together with a decrease in the hippocampal quinolinic acid (QA) expression compared to the sham-operated rats, suggested for the presence of endotoxin tolerance through the immunomodulatory activity of IDO in the brain. These data provide new insight into the underlying mechanisms of delirium, and future studies should further explore the role of IDO modulation and its therapeutic potential in delirium.

Exercise ameliorates hippocampal damage induced by Wi-Fi radiation; a biochemical, histological, and immunohistochemical study

INTRODUCTION

Nowadays, using electromagnetic devices (EMD) has been increased. However, the control of EMD hazards was poorly evaluated, especially those affected the hippocampus. Regular physical exercises are safe, easily, inexpensive, and acceptable for long-term use. It is reported that exercise protects against many health problems.

AIM

is to investigate the hypothesis of the possible prophylactic effect of exercise on the hippocampal damage induced by electromagnetic waves of Wi-Fi.

MATERIAL AND METHODS

Adult male albino rats were divided into four groups: group I (control), group II (exercise), group III (Wi-Fi), and group IV (exercise -Wi-Fi). Hippocampi were subjected to biochemical, histological, and immunohistochemical techniques.

RESULTS

In group III, a significant increase in the oxidative enzymes as well as decrease in antioxidant enzymes were detected in rat hippocampus. Additionally, the hippocampus showed degenerated pyramidal and granular neurons. An evident decrease in both PCNA and ZO-1 immunoreactivity was also noticed. In group IV, physical exercise alleviates the effect of Wi-Fi on previously mentioned parameters.

CONCLUSION

Regular physical exercise performance significantly minimizes the hippocampal damage and protects against the hazarders of chronic Wi-Fi radiation exposure.

Insight Into the Mechanism of Exercise Preconditioning in Ischemic Stroke

Exercise preconditioning has attracted extensive attention to induce endogenous neuroprotection and has become the hotspot in neurotherapy. The training exercise is given multiple times before cerebral ischemia, effectively inducing ischemic tolerance and alleviating secondary brain damage post-stroke. Compared with other preconditioning methods, the main advantages of exercise include easy clinical operation and being readily accepted by patients. However, the specific mechanism behind exercise preconditioning to ameliorate brain injury is complex. It involves multi-pathway and multi-target regulation, including regulation of inflammatory response, oxidative stress, apoptosis inhibition, and neurogenesis promotion. The current review summarizes the recent studies on the mechanism of neuroprotection induced by exercise, providing the theoretical basis of applying exercise therapy to prevent and treat ischemic stroke. In addition, we highlight the various limitations and future challenges of translational medicine from fundamental study to clinical application.

Preischemic Treadmill Exercise Ameliorates Memory Impairment and Microvasculature Damage in Rat Model of Chronic Cerebral Hypoperfusion

Purpose

Silent information regulator 1 (SIRT1) in the brain is essential for maintaining cellular homeostasis and plays a neuroprotective role in cerebral ischemia and neurodegenerative disorders. The effect of preischemic treadmill exercise on chronic cerebral hypoperfusion (CCH)-induced spatial learning memory impairment, microvascular injury, and blood-brain barrier (BBB) disruption in relation with SIRT1 expression was evaluated.

Methods

Prior to bilateral common carotid artery occlusion (BCCAO) surgery, the rats in the exercise groups performed low-intensity treadmill running for 30 minutes once daily during 8 weeks. BCCAO surgery was performed on male Wistar rats at 12 weeks of age. Spatial learning memory was measured using the Morris water maze test. Neuronal nuclear antigen, SIRT1, and rat endothelial cells antigen 1 were determined by immunohistochemistry and platelet-derived growth factor receptor beta was determined by immunofluorescence.

Results

Preischemic treadmill exercise ameliorated spatial learning memory impairment and enhanced SIRT1 expression in the BCCAO rats. Preischemic treadmill exercise ameliorated BCCAO-induced damage to microvasculature and pericytes that make up the BBB. The effect of preischemic treadmill exercise was lost with sirtinol treatment.

Conclusions

These results can apply treadmill exercise prior to cerebral ischemia as a rational preventive and therapeutic intervention strategy to improve cognitive dysfunction in CCH patients.

Potential therapeutic agents for ischemic white matter damage

Ischemic white matter damage (WMD) is increasingly being considered as one of the major causes of neurological disorders in older adults and preterm infants. The functional consequences of WMD triggers a progressive cognitive decline and dementia particularly in patients with ischemic cerebrovascular diseases. Despite the major stride made in the pathogenesis mechanisms of ischemic WMD in the last century, effective medications are still not available. So, there is an urgent need to explore a promising approach to slow the progression or modify its pathological course. In this review, we discussed the animal models, the pathological mechanisms and the potential therapeutic agents for ischemic WMD. The development in the studies of anti-oxidants, free radical scavengers, anti-inflammatory or anti-apoptotic agents and neurotrophic factors in ischemic WMD were summarized. The agents which either alleviate oligodendrocyte damage or promote its proliferation or differentiation may have potential value for the treatment of ischemic WMD. Moreover, drugs with multifaceted protective activities or a wide therapeutic window may be optimal for clinical translation.

Neuroprotective Effects of Exercise Postconditioning After Stroke via SIRT1-Mediated Suppression of Endoplasmic Reticulum (ER) Stress

While it is well-known that pre-stroke exercise conditioning reduces the incidence of stroke and the development of comorbidities, it is unclear whether post-stroke exercise conditioning is also neuroprotective. The present study investigated whether exercise postconditioning (PostE) induced neuroprotection and elucidated the involvement of SIRT1 regulation on the ROS/ER stress pathway. Adult rats were subjected to middle cerebral artery occlusion (MCAO) followed by either: (1) resting; (2) mild exercise postconditioning (MPostE); or (3) intense exercise postconditioning (IPostE). PostE was initiated 24 h after reperfusion and performed on a treadmill. At 1 and 3 days thereafter, we determined infarct volumes, neurological defects, brain edema, apoptotic cell death through measuring pro- (BAX and Caspase-3) and anti-apoptotic (Bcl-2) proteins, and ER stress through the measurement of glucose-regulated protein 78 (GRP78), inositol-requiring 1α (IRE1α), protein kinase RNA-like endoplasmic reticulum kinase (PERK), activating transcription factor 6 (ATF6), C/EBP homologous protein (CHOP), Caspase-12, and SIRT1. Proteins were measured by Western blot. ROS production was detected by flow cytometry.Compared to resting rats, both MPostE and IPostE significantly decreased brain infarct volumes and edema, neurological deficits, ROS production, and apoptotic cell death. MPostE further increased Bcl-2 expression and Bcl-2/BAX ratio as well as BAX and Caspase-3 expressions and ROS production (*p < 0.05). Both PostE groups saw decreases in ER stress proteins, while MPostE demonstrated a further reduction in GRP78 (***p < 0.001) and Caspase-12 (*p < 0.05) expressions at 1 day and IRE1α (**p < 0.01) and CHOP (*p < 0.05) expressions at 3 days. Additionally, both PostE groups saw significant increases in SIRT1 expression.In this study, both mild and intense PostE levels induced neuroprotection after stroke through SIRT1 and ROS/ER stress pathway. Additionally, the results may provide a base for our future study regarding the regulation of SIRT1 on the ROS/ER stress pathway in the biochemical processes underlying post-stroke neuroprotection. The results suggest that mild exercise postconditioning might play a similar neuroprotective role as intensive exercise and could be an effective exercise strategy as well.

Modulatory properties of extracellular matrix glycosaminoglycans and proteoglycans on neural stem cells behavior: Highlights on regenerative potential and bioactivity

Despite the poor regenerative capacity of the adult central nervous system (CNS) in mammals, two distinct regions, subventricular zone (SVZ) and the subgranular zone (SGZ), continue to generate new functional neurons throughout life which integrate into the pre-existing neuronal circuitry. This process is not fixed but highly modulated, revealing many intrinsic and extrinsic mechanisms by which this performance can be optimized for a given environment. The capacity for self-renewal, proliferation, migration, and multi-lineage potency of neural stem cells (NSCs) underlines the necessity of controlling stem cell fate. In this context, the native and local microenvironment plays a critical role, and the application of this highly organized architecture in the CNS has been considered as a fundamental concept in the generation of new effective therapeutic strategies in tissue engineering approaches. The brain extracellular matrix (ECM) is composed of biomacromolecules, including glycosaminoglycans, proteoglycans, and glycoproteins that provide various biological actions through biophysical and biochemical signaling pathways. Herein, we review predominantly the structure and function of the mentioned ECM composition and their regulatory impact on multiple and diversity of biological functions, including neural regeneration, survival, migration, differentiation, and final destiny of NSCs.

Differential Expression of Vascular Endothelial Growth Factor in the Cortex and Hippocampus upon Cerebral Hypoperfusion

BACKGROUND/AIM

Vascular endothelial growth factor (VEGF) provides tolerance against ischemic brain injury, yet, the pattern of VEGF expression in the neurogenic zones following chronic cerebral hypoperfusion has not been studied. Here we evaluated the immunoreactivity of VEGF in a rat model of chronic cerebral hypoperfusion.

MATERIALS AND METHODS

Chronic hypoperfusion was induced by bilateral common carotid artery ligation in rats. Immunohistochemistry was performed against hypoxia-inducible factor-1α (HIF-1α) and VEGF on brain sections.

RESULTS

The density of HIF1α-positive cells in the hypoxia group was increased in the cerebral cortex and hippocampus. Further, the density of VEGF-positive cells was significantly higher in the hypoxia group compared to the control group in the cerebral cortex whereas it was similar in the subventricular zone, and in the dentate gyrus in the hippocampus between the two groups.

CONCLUSION

The pattern of VEGF expression varies in different brain regions following chronic cerebral hypoperfusion.

Effect of Glycyrrhizic Acid on Scopolamine-Induced Cognitive Impairment in Mice

Purpose

Cognitive impairment is one of the main symptoms of Alzheimer disease and other dementias. Glycyrrhiza uralensis is a natural product that has a protective effect against cognitive impairment. In this study, we investigated whether glycyrrhizic acid, among the main bioactive components of Glycyrrhiza uralensis, has a neuroprotective effect on scopolamine-induced cognitive impairment.

Methods

Twenty-week-old male Institute of Cancer Research mice were used in this study. The scopolamine-induced cognitive impairment mice model was used. Glycyrrhizic acid was orally administered to mice once daily for 21 days, while scopolamine (1 mg/kg) treatment was delivered 30 minutes before behavioral tests. Donepezil (2 mg/kg) was used as a positive drug control. To evaluate the effect of glycyrrhizic acid, the following assessments were performed on hippocampal tissue: Y-maze test, acetylcholinesterase activity, antioxidant enzymes’ activity (superoxide dismutase, catalase). Western blotting for phosphor-extracellular signal-regulated kinase, P38, and c-Jun NH2-terminal kinase was conducted.

Results

We found that glycyrrhizic acid administration significantly improved scopolamine-induced cognitive impairment in the Y-maze test. The acetylcholinesterase activity, superoxide dismutase, and catalase activity in the glycyrrhizic acid-treated group showed a significant reversal of cognitive impairment compared with the scopolamine-treated group.

Conclusions

Our results suggest that glycyrrhizic acid has a neuroprotective effect on cognitive function in scopolamine-induced cognitive impairment.

Treadmill Exercise Improves Motor Function and Short-term Memory by Enhancing Synaptic Plasticity and Neurogenesis in Photothrombotic Stroke Mice

Purpose

Thrombotic stroke is a type of ischemic stroke characterized by motor dysfunction and memory impairments. In the present study, the effect of treadmill exercise on motor function and short-term memory was evaluated in relation with synaptic plasticity in the mice with photothrombotic stroke.

Methods

Photothrombotic stroke was induced by cortical photothrombotic vascular occlusion. The mice in the treadmill exercise groups performed running on a motorized treadmill for 28 days. Motor function was determined using rota-rod test and foot fault test. Step-through avoidance task was conducted to evaluate short-term memory. Immunohistochemistry for 5-bromo-2′-deoxyuridine and doublecortin was conducted to detect new cell generation. Postsynaptic density protein 95, synaptophysin, brain-derived neurotrophic factor (BDNF), and tyrosine kinase B receptor (TrkB) were determined using western blot. The number of dendritic spines was determined using Golgi stain.

Results

Treadmill exercise improved motor function and short-term memory in mice with the photothrombotic stroke. The infarct size was reduced and the number of dendritic spines and expression of postsynaptic density protein 95 and synaptophysin in the peri-infarct cortex and hippocampus were increased by treadmill exercise in photothrombotic stroke mice. Treadmill exercise enhanced neurogenesis through increasing the expression of the hippocampal BDNF and TrkB in photothrombotic stroke mice.

Conclusions

Treadmill exercise improved motor function and short-term memory through increasing synaptic plasticity and neurogenesis in photothrombotic stroke mice. Treadmill exercise can be used as an effective treatment strategy to improve brain function related to stroke.

Treadmill exercise ameliorates memory impairment through ERK-Akt-CREB-BDNF signaling pathway in cerebral ischemia gerbils

Neuronal cell death in the hippocampus by cerebral ischemia causes disability of memory function. Cerebral ischemia also alters the expressions of brain-derived neurotrophic factor (BDNF), cyclic adenosine monophosphate-responsive element binding protein (CREB), extracellular signal-regulated protein kinase (ERK), and phosphatidylinositol 3-kinase/protein kinase B (Akt). In the present study, we investigated the effect of treadmill exercise on cerebral ischemia in relation with ERK-Akt-CREB-BDNF signaling pathway in the hippocampus using gerbils. Induction of cerebral ischemia deteriorated short-term memory with suppression of phosphorylation of ERK-Akt-CREB-BDNF pathway in the hippocampus of gerbils. Enhancement of apoptosis in the hippocampus was accompanied in the ischemia gerbils. Treadmill exercise improved short-term memory through enhancing phosphorylation of ERK-Akt-CREB-BDNF pathway with suppressing apoptosis in the hip-pocampus of the ischemia gerbils. The present results suggest that improvement of memory function after cerebral ischemia by treadmill exercise may be involved in the ERK-Akt-CREB-BDNF signaling pathway, resulting in inhibition of apoptosis in the hippocampus.