Mechanisms of Preconditioning Exercise-Induced Neurovascular Protection in Stroke

Domain-Specific Physical Activity and Stroke in Sweden

Importance

Associations of domain-specific physical activity with stroke incidence and poststroke outcomes have not been extensively studied using long-term, population-based data.

Objective

To investigate associations of leisure time, work time, transport, and household physical activity with stroke incidence and death or dependency in activities of daily living (ADL) 3 months after stroke.

Design, Setting, and Participants

The prospective, population-based Interplay Between Genetic Susceptibility and External Factors (INTERGENE) cohort study was conducted among a random sample of individuals from an urban-rural area covering western Sweden; 3614 individuals aged 24 to 77 years were examined in 2001 to 2004, and 1394 individuals were reexamined in 2014 to 2016. The median (range) follow-up was 20.0 years (56 days to 21.9 years). Data were analyzed from September through October 2023.

Exposure

Physical activity levels were self-reported for leisure time, work time, transportation, and household domains. The mean number of steps taken over a 6-day period was collected in a subgroup of participants using a sealed pedometer.

Main Outcomes and Measures

Follow-up for stroke incidence and mortality rates continued until December 31, 2022. The composite outcome of death or ADL dependency was assessed at 3 months after stroke.

Results

Among 3614 individuals (mean [SD] age, 51.4 [13.1] years; 1910 female [52.9%]); 269 individuals (7.4%) developed stroke, of whom 120 individuals (44.6%) were dead or ADL dependent at 3 months. Intermediate (adjusted hazard ratio [aHR], 0.54; 95% CI, 0.38-0.77) and high (aHR, 0.47; 95% CI, 0.31-0.73) levels of leisure time physical activity were associated with a reduced incidence of stroke compared with low levels, as was an intermediate level of physical activity in transportation (aHR, 0.69; 95% CI, 0.52-0.93). High levels of leisure time physical activity were also associated with a reduced risk of poststroke death or ADL dependency (adjusted odds ratio, 0.34; 95% CI, 0.16-0.71) compared with low levels. Work time and household physical activity were not associated with stroke incidence or stroke outcomes. In exploratory subgroup analyses, there were interactions between physical activity and smoking (current smoking or smoking in the past year associated with stroke risk only in participants with low or intermediate physical activity: aHR, 2.33; 95% CI, 1.72-3.15) and family history of stroke (first-degree relative with a history of stroke associated with stroke risk only in participants with low or intermediate physical activity: aHR, 1.73; 95% CI, 1.27-2.38).

Conclusions and Relevance

In this study, leisure time and transport-related physical activities were associated with a reduced risk of stroke. A high level of leisure time physical activity was also associated with a lower risk of death or ADL dependency 3 months after stroke.

Prestroke physical activity is associated with admission haematoma volume and the clinical outcome of intracerebral haemorrhage

BACKGROUND

Prestroke physical activity (PA) has been linked to improved outcomes after intracerebral haemorrhage (ICH), but its association with ICH volume is unknown. We aimed to investigate associations of prestroke PA with location-specific haematoma volume and the clinical outcome of ICH.

METHODS

All patients with primary ICH, admitted to three hospitals between 2014 and 2019, were included. Patients performing light PA ≥4 hour/week the year before stroke were considered physically active. Haematoma volumes were assessed from admission brain imaging. Adjusted associations were estimated using multivariate linear and logistic regression models. Haematoma volume was explored as mediator to the relationship between prestroke PA and mild stroke severity (0-4 points on the National Institutes of Health Stroke Scale), a good 1-week functional status (0-3 points on the modified Rankin Scale) and 90-day survival. Average direct effects (ADE) and average causal mediation effects (ACME) were computed.

RESULTS

Of 686 primary ICH cases, 349 were deep, 240 lobar and 97 infratentorial. Prestroke PA predicted smaller haematoma volumes in deep ICH (β=-0.36, SE=0.09, p<0.001) and lobar ICH (β=-0.23, SE=0.09, p=0.016). Prestroke PA was also associated with mild stroke severity (OR 2.53, 95% CI 1.59 to 4.01), a good 1-week functional status (OR 2.12, 95% CI 1.37 to 3.30) and 90-day survival (OR 3.48, 95% CI 2.06 to 5.91). Haematoma volume partly mediated the relationships between PA and stroke severity (ADE 0.08, p=0.004; ACME 0.10, p<0.001), 1-week functional status (ADE 0.07, p=0.03; ACME 0.10, p<0.001) and 90-day survival (ADE 0.14, p<0.001; ACME 0.05, p<0.001).

CONCLUSIONS

Light PA ≥4 hour/week prior to ICH was associated with smaller haematoma volumes in deep and lobar locations. Physically active patients with ICH had a higher likelihood of mild stroke, a good 1-week functional status and 90-day survival, in part mediated by smaller haematoma volumes on admission.

Astrocyte-Neuronal Communication and Its Role in Stroke

Astrocytes are the most abundant glial cells in the central nervous system. These cells are an important hub for intercellular communication. They participate in various pathophysiological processes, including synaptogenesis, metabolic transformation, scar production, and blood-brain barrier repair. The mechanisms and functional consequences of astrocyte-neuron signaling are more complex than previously thought. Stroke is a disease associated with neurons in which astrocytes also play an important role. Astrocytes respond to the alterations in the brain microenvironment after stroke, providing required substances to neurons. However, they can also have harmful effects. In this review, we have summarized the function of astrocytes, their association with neurons, and two paradigms of the inflammatory response, which suggest that targeting astrocytes may be an effective strategy for treating stroke.

Potential mechanisms of multimodal prehabilitation effects on surgical complications: a narrative review

Continuous advances in prehabilitation research over the past several decades have clarified its role in improving preoperative risk factors, yet the evidence demonstrating reduced surgical complications remains uncertain. Describing the potential mechanisms underlying prehabilitation and surgical complications represents an important opportunity to establish biological plausibility, develop targeted therapies, generate hypotheses for future research, and contribute to the rationale for implementation into the standard of care. In this narrative review, we discuss and synthesize the current evidence base for the biological plausibility of multimodal prehabilitation to reduce surgical complications. The goal of this review is to improve prehabilitation interventions and measurement by outlining biologically plausible mechanisms of benefit and generating hypotheses for future research. This is accomplished by synthesizing the available evidence for the mechanistic benefit of exercise, nutrition, and psychological interventions for reducing the incidence and severity of surgical complications reported by the American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP). This review was conducted and reported in accordance with a quality assessment scale for narrative reviews. Findings indicate that prehabilitation has biological plausibility to reduce all complications outlined by NSQIP. Mechanisms for prehabilitation to reduce surgical complications include anti-inflammation, enhanced innate immunity, and attenuation of sympathovagal imbalance. Mechanisms vary depending on the intervention protocol and baseline characteristics of the sample. This review highlights the need for more research in this space while proposing potential mechanisms to be included in future investigations.

Alleviation of ischemic brain injury by exercise preconditioning is associated with modulation of autophagy and mitochondrial dynamics in cerebral cortex of female aged mice

Evidence from clinical studies and preclinical studies supports that exercise preconditioning can not only reduce the risk of stroke but also improve brain tissue and functional outcome after stroke. It has been demonstrated that autophagy and mitochondrial dynamics are involved in ischemic stroke. However, it is still unclear whether exercise preconditioning-induced neuroprotection against stroke is associated with modulation of autophagy and mitochondrial dynamics. Although age and sex interactively affect ischemic stroke risk, incidence, and outcome, studies based on young male animals are most often used to explore the role of exercise preconditioning in the prevention of ischemic stroke. In the current study, we examined whether exercise preconditioning could modulate autophagy and mitochondrial dynamics in a brain ischemia and reperfusion (I/R) model of female aged mice. The results showed that exercise preconditioning reduced infarct volume and improved neurological deficits. Additionally, increased levels of autophagy-related proteins LC3-II/LC3-I, LC3-II, p62, Atg7, and mitophagy-related proteins Bnip3L and Parkin, as well as increased levels of mitochondrial fusion modulator Mfn2 and mitochondrial fission modulator Drp1 in the ischemic cortex of female aged mice at 12 h after I/R were present. Our results could contribute to a better understanding of exercise preconditioning-induced neuroprotection against ischemic stroke for the elderly.

Impact of prestroke physical activity and citalopram treatment on poststroke depressive symptoms: a secondary analysis of data from the TALOS randomised controlled trial in Denmark

OBJECTIVES

To investigate the association between prestroke physical activity and depressive symptoms up to 6 months after stroke and examine if citalopram treatment modified the association.

DESIGN

A secondary analysis of data from the multicentre randomised controlled trial The Efficacy of Citalopram Treatment in Acute Ischemic Stroke (TALOS).

SETTING AND PARTICIPANTS

TALOS was conducted at multiple stroke centres in Denmark from 2013 to 2016. It enrolled 642 non-depressed patients with first-ever acute ischaemic stroke. Patients were eligible for this study if a prestroke physical activity level was assessed by the Physical Activity Scale for the Elderly (PASE).

INTERVENTIONS

All patients were randomised to citalopram or placebo for 6 months.

OUTCOMES

Depressive symptoms 1 and 6 months after stroke measured on the Major Depression Inventory (MDI) ranging from 0 to 50.

RESULTS

A total of 625 patients were included. Median (IQR) age was 69 (60-77) years, 410 (65.6%) were men, 309 (49.4 %) received citalopram and median (IQR) prestroke PASE score was 132.5 (76-197). Higher prestroke PASE quartile, compared with the lowest PASE quartile, was associated with fewer depressive symptoms both after 1 month (mean difference third quartile -2.3 (-4.2, -0.5), p=0.013, mean difference fourth quartile -2.4 (-4.3, -0.5), p=0.015) and 6 months after stroke (mean difference third quartile -3.3 (-5.5, -1.2), p=0.002, mean difference fourth quartile -2.8 (-5.2, -0.3), p=0.027). There was no interaction between citalopram treatment and prestroke PASE score on poststroke MDI scores (p=0.86).

CONCLUSIONS

A higher prestroke physical activity level was associated with fewer depressive symptoms 1 and 6 months after stroke. Citalopram treatment did not seem to modify this association.

TRIAL REGISTRATION NUMBERS

NCT01937182 (ClinicalTrials.gov) and 2013-002253-30 (EUDRACT).

Exercise pretreatment alleviates neuroinflammation and oxidative stress by TFEB-mediated autophagic flux in mice with ischemic stroke

BACKGROUND

Neuroinflammation and oxidative stress are important pathological mechanisms underlying cerebral ischemic stroke. Increasing evidence suggests that regulation autophagy in ischemic stroke may improve neurological functions. In this study, we aimed to explore whether exercise pretreatment attenuates neuroinflammation and oxidative stress in ischemic stroke by improving autophagic flux.

METHODS

2,3,5-Triphenyltetrazolium chloride staining was used to determine the infarction volume, and modified Neurological Severity Scores and rotarod test were used to evaluate neurological functions after ischemic stroke. The levels of oxidative stress, neuroinflammation, neuronal apoptosis and degradation, autophagic flux, and signaling pathway proteins were determined using immunofluorescence, dihydroethidium, TUNEL, and Fluoro-Jade B staining, western blotting, and co-immunoprecipitation.

RESULTS

Our results showed that, in middle cerebral artery occlusion (MCAO) mice, exercise pretreatment improved neurological functions and defective autophagy, and reduced neuroinflammation and oxidative stress. Mechanistically, after using chloroquine, impaired autophagy abolished the neuroprotection of exercise pretreatment. And transcription factor EB (TFEB) activation mediated by exercise pretreatment contributes to improving autophagic flux after MCAO. Furthermore, we showed that TFEB activation mediated by exercise pretreatment in MCAO was regulated by the AMPK-mTOR and AMPK-FOXO3a-SKP2-CARM1 signaling pathways.

CONCLUSIONS

Exercise pretreatment has the potential to improve the prognosis of ischemic stroke patients, and it can exert neuroprotective effects in ischemic stroke by inhibiting neuroinflammation and oxidative stress, which might be due to the TFEB-mediated autophagic flux. And targeting autophagic flux may be promising strategies for the treatment of ischemic stroke.

Neuroprotective effects of pre-ischemic exercise are linked to expression of NT-3/NT-4 and TrkB/TrkC in rats

INTRODUCTION AND OBJECTIVE

Stroke causes irreversible damage, particularly to the hippocampus. Evidence suggests that exercise training may mitigate adverse structural and functional consequences of an ischemic lesion in the brain. The purpose of this study was to investigate the effects of preconditioning exercise on expression of neurotrophic factor genes and proteins in hippocampalCA1 region and their relationship with sensorimotor recovery following global ischemia/reperfusion (Is/Re) injury in a rat model of stroke.

METHODS

Male Wistar rats were randomly assigned to Exercise+Ischemia/Reperfusion (Ex+Is/Re),Control+Ischemia/Reperfusion (Co+Is/Re), and Sham treatments. Rats in the exercise groups ran on a treadmill for 45 min/d for five days/week for 8 consecutive weeks prior to Is/Re lesion.Ischemia was induced by common carotid artery occlusion (CCAO). The ladder rung walking task was used to assess functional impairments and recovery following ischemic lesion.Tissue from hippocampal area CA1 was inspected for ischemia-induced cell loss and gene and protein expression linked to neurotrophins NT-3, NT-4, and their receptorsTrkB and TrkC.

RESULTS

CCAO caused hippocampal cell death in CA1 and resulted in significant sensori motor impairments in the ladder rung walking task. In contrast, pre-ischemic exercise considerably reduced cell death and supported sensorimotor recovery following CCAO.In addition, NT-3, NT-4,TrkB and TrkC gene expression and their protein levels were significantly increased inthe Ex+Is/Re group compared to Co+Is/Re (p < 0.05).

CONCLUSION

The findings showed that pre-ischemic exercise can exert neuroprotective effects via NT-3 and NT-4 pathways against ischemia in hippocampal CA1 neurons and promote post-injury sensorimotor recovery.

Intermittent hypoxia conditioning as a potential prevention and treatment strategy for ischemic stroke: Current evidence and future directions

Ischemic stroke (IS) is the leading cause of disability and death worldwide. Owing to the aging population and unhealthy lifestyles, the incidence of cerebrovascular disease is high. Vascular risk factors include hypertension, diabetes, dyslipidemia, and obesity. Therefore, in addition to timely and effective reperfusion therapy for IS, it is crucial to actively control these risk factors to reduce the incidence and recurrence rates of IS. Evidence from human and animal studies suggests that moderate intermittent hypoxia (IH) exposure is a promising therapeutic strategy to ameliorate common vascular risk factors and comorbidities. Given the complex pathophysiological mechanisms underlying IS, effective treatment must focus on reducing injury in the acute phase and promoting repair in the recovery phase. Therefore, this review discusses the preclinical perspectives on IH conditioning as a potential treatment for neurovascular injury and highlights IH pre and postconditioning strategies for IS. Hypoxia conditioning reduces brain injury by increasing resistance to acute ischemic and hypoxic stress, exerting neuroprotective effects, and promoting post-injury repair and regeneration. However, whether IH produces beneficial effects depends not only on the hypoxic regimen but also on inter-subject differences. Therefore, we discuss the factors that may influence the effectiveness of IH treatment, including age, sex, comorbidities, and circadian rhythm, which can be used to help identify the optimal intervention population and treatment protocols for more accurate, individualized clinical translation. In conclusion, IH conditioning as a non-invasive, non-pharmacological, systemic, and multi-targeted intervention can not only reduce brain damage after stroke but can also be applied to the prevention and functional recovery of IS, providing brain protection at different stages of the disease. It represents a promising therapeutic strategy. For patients with IS and high-risk groups, IH conditioning is expected to develop as an adjunctive clinical treatment option to reduce the incidence, recurrence, disability, and mortality of IS and to reduce disease burden.

Running from Stress: Neurobiological Mechanisms of Exercise-Induced Stress Resilience

Chronic stress, even stress of a moderate intensity related to daily life, is widely acknowledged to be a predisposing or precipitating factor in neuropsychiatric diseases. There is a clear relationship between disturbances induced by stressful stimuli, especially long-lasting stimuli, and cognitive deficits in rodent models of affective disorders. Regular physical activity has a positive effect on the central nervous system (CNS) functions, contributes to an improvement in mood and of cognitive abilities (including memory and learning), and is correlated with an increase in the expression of the neurotrophic factors and markers of synaptic plasticity as well as a reduction in the inflammatory factors. Studies published so far show that the energy challenge caused by physical exercise can affect the CNS by improving cellular bioenergetics, stimulating the processes responsible for the removal of damaged organelles and molecules, and attenuating inflammation processes. Regular physical activity brings another important benefit: increased stress robustness. The evidence from animal studies is that a sedentary lifestyle is associated with stress vulnerability, whereas a physically active lifestyle is associated with stress resilience. Here, we have performed a comprehensive PubMed Search Strategy for accomplishing an exhaustive literature review. In this review, we discuss the findings from experimental studies on the molecular and neurobiological mechanisms underlying the impact of exercise on brain resilience. A thorough understanding of the mechanisms underlying the neuroprotective potential of preconditioning exercise and of the role of exercise in stress resilience, among other things, may open further options for prevention and therapy in the treatment of CNS diseases.

Efficacy of Chinese herbal medicine for tPA thrombolysis in experimental stroke: A systematic review and meta-analysis

BACKGROUND

Tissue-type plasminogen activator (tPA) remains the sole FDA approved thrombolytic drug for ischemic stroke. But delayed thrombolytic therapy with tPA may increase the risk of hemorrhagic transformation. Many Chinese herbal medicines have been used as tPA helpers to enhance the capacity of tPA and minimize the risk of hemorrhagic transformation. The efficacy of Chinese herbal medicines on tPA thrombolysis is not systematically analyzed.

METHODS

We searched the following three databases up to January 2022: Web of Science, PubMed, and Scopus. Studies that reported the efficacy and safety of Chinese herbal medicines on tPA thrombolysis in experimental stroke were included. The efficacy outcomes were neurological score and infarct volume, the safety outcomes were cerebral hemorrhage and blood brain barrier (BBB) damage. We used the checklist of CAMARADES to assess the quality of included studies. Standardized mean difference (SMD) with 95% confidence intervals were used to assess all the outcomes. Subgroup analyses were performed to explore the sources of heterogeneity. Trim and fill method and Egger's test were used to assess the potential publication bias. Sensitivity analyses were used to identify the stability of the results.

RESULTS

A total of nine studies including 11 Chinese herbal medicines fulfilled the inclusion criteria and were subsequently analyzed. The pooled data demonstrated that Chinese herbal medicines improved neurological score (2.23 SMD, 1.42-3.04), infarct volume (1.08 SMD, 0.62-1.54), attenuated cerebral hemorrhage (1.87 SMD, 1.34-2.4), and BBB dysfunction (1.9 SMD, 1.35-2.45) following tPA thrombolysis in experimental stroke. Subgroup analysis indicated that the route of drug delivery, dosage of tPA, and stroke model used may be factors inducing heterogeneity and influencing the efficacy.

CONCLUSION

Treatment with Chinese herbal medicines significantly improved neurological score and infarct volume, reduced cerebral hemorrhage and BBB damage after tPA thrombolysis. This study supports Chinese herbal medicine as an adjuvant therapy in reducing the side effects of tPA thrombolysis after acute ischemic stroke. The results should be interpreted with more caution since this article was based on animal studies.

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.

Exploring Alternative Measurements of Cardiorespiratory Fitness in Patients With Mild Ischemic Stroke at Acute Phase

Background

While emerging studies have suggested an association of cardiorespiratory fitness (CRF) with stroke risk and overall health outcomes, little is known regarding the optimum methods of CRF measurement in patients with mild acute ischemic stroke.

Objective

The aim of this study was to explore the association between the 6-min walk distance (6MWD) and other measurements related to CRF in patients with mild ischemic stroke at the acute stage.

Methods

A total of 30 patients with stroke and 71 healthy subjects matched for age and grip strength (GS) were prospectively recruited. All patients were within 14 days after stroke onset and presented mild motor impairment (with a full score of Fugl-Meyer Motor Assessment). Demographic data of both groups and clinical information of the stroke group were documented, and the CRF comparison between the two groups was conducted. Each participant underwent a one-time assessment of 6MWD and a series of measurements related to CRF, including GS, 10-m walk test (10mWT), five-times sit-to-stand time (FTSST), functional reaching test (FRT), Berg Balance Scale (BBS), and waistline. Pearson's product-moment correlation coefficient test and multiple linear regression were performed to explore the indicators of CRF.

Results

Significant moderate correlations (0.3 < r <0.6) were found between 6MWD and GS of left hand (GS-left) (r = 0.573, p = 0.001), GS of right hand (GS-right) (r = 0.524, p = 0.003), FTSST (r = −0.551, p = 0.002), 10mWT (r = 0.554, p = 0.001), and FRT (r = 0.449, p = 0.021) in the patient group. While 6MWD displayed significant moderate correlations with waistline (r = 0.364, p = 0.002), 10mWT (r = 0.512, p < 0.001), FTSST (r = −0.573, p < 0.001), and FRT (r = 0.550, p < 0.001) in the healthy group. All these dependent variables were entered into a stepwise multiple linear regression analysis to evaluate their values in estimating CRF as measured by 6MWD in each group. Analyses suggested that GS-left (p = 0.002) and FTSST (p = 0.003) were the indicators of CRF in the patient group with stroke and explained 51.4% of the variance of 6MWD (R² = 0.514); FTSST (p < 0.001), 10mWT (p < 0.001), and FRT (p = 0.021) were the indicators of CRF in the healthy group and explained 58.9% of variance of 6MWD (R² = 0.589).

Conclusions

Our data confirmed that CRF is impaired in patients with mild ischemic stroke at the acute phase. Moreover, GS-left may be an optional indicator of CRF in patients with mild acute ischemic stroke, but not in healthy people.

Clinical Trial Registration

www.chictr.org.cn, identifier: ChiCTR2000031379.

Exercise improves choroid plexus epithelial cells metabolism to prevent glial cell-associated neurodegeneration

Recent studies have shown that physical activities can prevent aging-related neurodegeneration. Exercise improves the metabolic landscape of the body. However, the role of these differential metabolites in preventing neurovascular unit degeneration (NVU) is still unclear. Here, we performed single-cell analysis of brain tissue from young and old mice. Normalized mutual information (NMI) was used to measure heterogeneity between each pair of cells using the non-negative Matrix Factorization (NMF) method. Astrocytes and choroid plexus epithelial cells (CPC), two types of CNS glial cells, differed significantly in heterogeneity depending on their aging status and intercellular interactions. The MetaboAnalyst 5.0 database and the scMetabolism package were used to analyze and calculate the differential metabolic pathways associated with aging in the CPC. These mRNAs and corresponding proteins were involved in the metabolites (R)-3-Hydroxybutyric acid, 2-Hydroxyglutarate, 2-Ketobutyric acid, 3-Hydroxyanthranilic acid, Fumaric acid, L-Leucine, and Oxidized glutathione pathways in CPC. Our results showed that CPC age heterogeneity-associated proteins (ECHS1, GSTT1, HSD17B10, LDHA, and LDHB) might be directly targeted by the metabolite of oxidized glutathione (GSSG). Further molecular dynamics and free-energy simulations confirmed the insight into GSSG's targeting function and free-energy barrier on these CPC age heterogeneity-associated proteins. By inhibiting these proteins in CPC, GSSG inhibits brain energy metabolism, whereas exercise improves the metabolic pathway activity of CPC in NVU by regulating GSSG homeostasis. In order to develop drugs targeting neurodegenerative diseases, further studies are needed to understand how physical exercise enhances NVU function and metabolism by modulating CPC-glial cell interactions.