Exacerbation of Brain Injury by Post-Stroke Exercise Is Contingent Upon Exercise Initiation Timing

β-hydroxybutyrate and ischemic stroke: roles and mechanisms

Stroke is a significant global burden, causing extensive morbidity and mortality. In metabolic states where glucose is limited, ketone bodies, predominantly β-hydroxybutyrate (BHB), act as alternative fuel sources. Elevated levels of BHB have been found in the ischemic hemispheres of animal models of stroke, supporting its role in the pathophysiology of cerebral ischemia. Clinically, higher serum and urinary BHB concentrations have been associated with adverse outcomes in ischemic stroke, highlighting its potential utility as a prognostic biomarker. In both animal and cellular models, exogenous BHB administration has exhibited neuroprotective effects, reduction of infarct size, and improvement of neurological outcomes. In this review, we focus on the role of BHB before and after ischemic stroke, with an emphasis on the therapeutic potential and mechanisms of ketone administration after ischemic stroke.

Advancing stroke recovery: unlocking the potential of cellular dynamics in stroke recovery

Stroke stands as a predominant cause of mortality and morbidity worldwide, and there is a pressing need for effective therapies to improve outcomes and enhance the quality of life for stroke survivors. In this line, effective efferocytosis, the clearance of apoptotic cells, plays a crucial role in neuroprotection and immunoregulation. This process involves specialized phagocytes known as "professional phagocytes" and consists of four steps: "Find-Me," "Eat-Me," engulfment/digestion, and anti-inflammatory responses. Impaired efferocytosis can lead to secondary necrosis and inflammation, resulting in adverse outcomes following brain pathologies. Enhancing efferocytosis presents a potential avenue for improving post-stroke recovery. Several therapeutic targets have been identified, including osteopontin, cysteinyl leukotriene 2 receptor, the µ opioid receptor antagonist β-funaltrexamine, and PPARγ and RXR agonists. Ferroptosis, defined as iron-dependent cell death, is now emerging as a novel target to attenuate post-stroke tissue damage and neuronal loss. Additionally, several biomarkers, most importantly CD163, may serve as potential biomarkers and therapeutic targets for acute ischemic stroke, aiding in stroke diagnosis and prognosis. Non-pharmacological approaches involve physical rehabilitation, hypoxia, and hypothermia. Mitochondrial dysfunction is now recognized as a major contributor to the poor outcomes of brain stroke, and medications targeting mitochondria may exhibit beneficial effects. These strategies aim to polarize efferocytes toward an anti-inflammatory phenotype, limit the ingestion of distressed but viable neurons, and stimulate efferocytosis in the late phase of stroke to enhance post-stroke recovery. These findings highlight promising directions for future research and development of effective stroke recovery therapies.

Protective effects of early exercise on neuroinflammation, and neurotoxicity associated by traumatic brain injury: a behavioral and neurochemical approach

OBJECTIVE

The benefits of exercise in TBI have been proven. However, the time-dependent effects of exercise initiation and the involved mechanisms are controversial. We investigated the effects of preconditioning, continuous, early, and delayed treadmill exercise on motor behavior, brain edema, inflammation, and oxidative stress in experimental traumatic brain injury (TBI).

MATERIALS AND METHODS

48 male rats were assigned into two groups: sedentary control (Sham and TBI) and exercise groups: 1MB (preconditioning, initiation beginning at 1 month before trauma), 1MBA (continuous, initiation beginning at 1 month before and continuing 1 month after trauma), 24hA (early, initiation beginning at 24 h after trauma), and 1WA (delay, initiation beginning at 1 week after trauma). The rats in exercise groups were forced to run on a treadmill five days a week for 30 min per day. Rotarod and open file were used to assess motor behavior. ELISA was also used to measure total antioxidant capacity (TAC), tumor necrosis factor-alpha (TNF-α), and malondialdehyde (MDA) in serum and CSF.

RESULTS

Exercise significantly decreased neurological impairments, motor deficits, and apoptosis compared with the sedentary group. Early (within 24 h) and ongoing (1 MBA) exercise significantly improved motor behavior after TBI. In addition, these exercise programs inhibited brain edema and the number of apoptotic cells. MDA and TNF-α levels increased in all exercise groups, but the effects were greater after early exercise than after delayed exercise, resulting in a significant decrease in TAC levels in serum and CSF. We discovered a positive correlation between MDA, TAC, and TNF-α concentration in serum and CSF.

CONCLUSION

Our finding suggests that early exercise (24hA) and 1MBA groups afford neuroprotection and reduce the second injury consequence, probably by reducing neuronal apoptosis and oxidative stress.

A novel stroke rehabilitation strategy and underlying stress granule regulations through inhibition of NLRP3 inflammasome activation

OBJECTIVE

Dynamic changes in ischemic pathology after stroke suggested a "critical window" of enhanced neuroplasticity immediately after stroke onset. Although physical exercise has long been considered a promising strategy of stroke rehabilitation, very early physical exercise may exacerbate brain injury. Since remote ischemic conditioning (RIC) promotes neuroprotection and neuroplasticity, the present study combined RIC with sequential exercise to establish a new rehabilitation strategy for a better rehabilitative outcome.

METHODS

A total of 120 adult male Sprague-Dawley rats were used and divided into five groups: (1) sham, (2) stroke, (3) stroke with exercise, (4) stroke with RIC, and (5) stroke with RIC followed by exercise. Brain damage was evaluated by infarct volume, neurological deficit, cell death, and lactate dehydrogenase (LDH) activity. Long-term functional outcomes were determined by grid walk tests, rotarod tests, beam balance tests, forelimb placing tests, and the Morris water maze. Neuroplasticity was evaluated through measurements of both mRNA and protein levels of synaptogenesis (synaptophysin [SYN], post-synaptic density protein-95 [PSD-95], and brain-derived neurotrophic factor [BDNF]) and angiogenesis (vascular endothelial growth factor [VEGF], angiopoietin-1 [Ang-1], and angiopoietin-2 [Ang-2]). Inflammasome activation was measured by concentrations of interleukin-18 (IL-18) and IL-1β detected by enzyme-linked immunosorbent assay (ELISA) kits, mRNA expressions of NLR pyrin domain containing 3 (NLRP3), apoptosis-associated speck-like protein containing a C-terminal caspase recruitment domain (ASC), IL-18 and IL-1β, and protein quantities of NLRP3, ASC, cleaved-caspase-1, gasdermin D-N (GSDMD-N), and IL-18 and IL-1β. Stress granules (SGs), including GTPase-activating protein-binding protein 1 (G3BP1), T cell-restricted intracellular antigen-1 (TIA1), and DEAD-box RNA helicase 3X (DDX3X) were evaluated at mRNA and protein levels. The interactions between DDX3X with NLRP3 or G3BP1 were determined by immunofluorescence and co-immunoprecipitation.

RESULTS

Early RIC decreased infarct volumes, neurological deficits, cell death, and LDH activity at post-stroke Day 3 (p < 0.05). All treatment groups showed significant improvement in functional outcomes, including sensory, motor, and cognitive functions. RIC and exercise, as compared to RIC or physical exercise alone, had improved functional outcomes after stroke (p < 0.05), as well as synaptogenesis and angiogenesis (p < 0.05). RIC significantly reduced mRNA and protein expressions of NLRP3 (p < 0.05). SGs formation peaked at 0 h after ischemia, then progressively decreased until 24 h postreperfusion, which was reversed by RIC (p < 0.05). The assembly of SGs consumed DDX3X and then inhibited NLRP3 inflammasome activation.

CONCLUSIONS

RIC followed by exercise induced a better rehabilitation in ischemic rats, while early RIC alleviated ischemia-reperfusion injury via stress-granule-mediated inhibition of NLRP3 inflammasome.

Optimal rehabilitation strategies for early postacute stroke recovery: An ongoing inquiry

Early rehabilitation is crucial in reducing stroke-related disability, but the optimal training model remains unclear. We conducted a trial comparing different initiation timings and intensities of mobilization strategies after stroke. Results showed that early intensive mobilization had favorable outcomes at 3 months post-stroke, while very early intensive mobilization had poorer chances of favorable outcomes. Our investigation into brain injury mechanisms induced by very early exercise within 24 hours of stroke onset aligned with guidelines advising against high-dose very early mobilization. Additionally, we are studying the effects of various exercise intensities and frequencies on early stroke rehabilitation. Integrated rehabilitation models, such as combining remote ischemic conditioning (RIC) with exercise (RICE), hold promise. Our study found RICE to be safe and feasible for early rehabilitation of acute ischemic stroke patients, and further research is underway to determine its efficacy in a larger sample size. Despite extensive research, identifying the most effective early recovery strategies remains a complex challenge, necessitating ongoing work in the field of early rehabilitation after stroke.

Exercise intensity and sex alter neurometabolic, transcriptional, and functional recovery following traumatic brain injury

Physical exercise represents a potentially inexpensive, accessible, and optimizable rehabilitation approach to traumatic brain injury (TBI) recovery. However, little is known about the impact of post-injury exercise on the neurometabolic, transcriptional, and cognitive outcomes following a TBI. In the current study, we examined TBI outcomes in adolescent male and female mice following a controlled cortical impact (CCI) injury. Mice underwent a 10-day regimen of sedentary, low-, moderate-, or high-intensity treadmill exercise and were assessed for cognitive function, histopathology, mitochondrial function, and oxidative stress. Among male mice, low-moderate exercise improved cognitive recovery, and reduced cortical lesion volume and oxidative stress, whereas high-intensity exercise impaired both cognitive recovery and mitochondrial function. On the other hand, among female mice, exercise had an intermediate effect on cognitive recovery but significantly improved brain mitochondrial function. Moreover, single nuclei RNA sequencing of perilesional brain tissue revealed neuronal plasticity-related differential gene expression that was largely limited to the low-intensity exercise injured males. Taken together, these data build on previous reports of the neuroprotective capacity of exercise in a TBI model, and reveal that this rehabilitation strategy impacts neurometabolic, functional, and transcriptional outcome measures in an intensity- and sex-dependent manner.

Effects of exercise intensity on the reactive astrocyte polarization in the medial prefrontal cortex

PURPOSE

Physical exercise contributes to neuroplasticity by promoting cognitive functions, such as learning and memory. The astrocytic phenotype is closely associated with synaptic plasticity. This study aimed to determine whether astrocyte polarization and synaptic alterations in the medial prefrontal cortex (mPFC) are affected differently by high- and moderate-intensity exercise.

METHODS

Mice were subjected to moderate-(MIE) and high-intensity treadmill running (HIE). Memory capacity was assessed using the novel object recognition and modified Y-maze tests. For immunohistochemistry, c-Fos-positive cells were counted in the mPFC. Using western blot analysis, astrocyte phenotype markers were quantified in whole-cell lysates, and synaptic molecules were determined in the synaptosomal fraction.

RESULTS

Exercise lengthened the approach time to novel objects regardless of intensity in the NOR test, whereas MIE only improved spatial memory. Exercise induced c-Fos expression in the anterior cingulate cortex (ACC) and c-Fos-positive cells were higher in MIE than in HIE in the ACC area. In the prelimbic/infralimbic cortex region, the number of c-Fos-positive cells were enhanced in MIE and decreased in HIE mice. The A1 astrocyte marker (C3) was increased in HIE mice, while the A2 astrocyte markers were enhanced in exercised mice, regardless of the intensity. In the synaptosomal fraction, synaptic proteins were elevated by exercise regardless of intensity.

CONCLUSION

These results suggest that exercise intensity affects neuronal plasticity by modulating the reactive state of astrocytes in the mPFC.

The Key Role of Initiation Timing on Stroke Rehabilitation by Remote Ischemic Conditioning with Exercise (RICE)

OBJECTIVE

Physical therapy is an integral part of post-stroke rehabilitation. Remote ischemic conditioning (RIC) induces neuroprotection within 24 hours after stroke, during which exercise is unsafe and ineffective. We combined RIC with exercise to establish a novel rehabilitation strategy, RICE (RIC+Exercise). The aim of this study was to optimize the RICE protocol in neurorehabilitation.

METHODS

Thirty-two adult male Sprague-Dawley rats were placed in one of four groups: stroke with no rehabilitation or stroke with various RICE protocols. To further understand the mechanisms underlying neurorehabilitation, sixteen adult male Sprague-Dawley were added, each placed in one of two groups: stroke with exerciseor RIC  . Long-term functional outcomes were determined by beam balance, rota-rod, grid walk, forelimb placing, and Morris water maze tests up to 28 days after stroke (p < 0.05). Changes in neuroplasticity including synaptogenesis (assessed by measuring synaptophysin, post-synaptic density protein-95, and brain-derived neutrophic factor), angiogenesis (via vascular endothelial growth factor, Angiopoietin-1, and Angiopoietin-2), and regulatory molecules (including hypoxia inducible factor-1α, phospholipase D2 and the mechanistic target of rapamycin pathway), were all measured at both mRNA and protein levels (p < 0.05).

RESULTS

All rehabilitation groups showed significant improvement in functional outcomes and levels of synaptogenesis and angiogenesis. 5 day RICE groups, in which RIC was started five days prior to exercise, demonstrated the greatest improvement among these parameters. The results also suggested that the HIF-1α/PLD2/mTOR signaling pathway may be implicated in post-stroke neuroplasticity.

CONCLUSIONS

RICE, particularly RIC initiation at hour 6 post-reperfusion followed by exercise on day 5, enhanced post-stroke rehabilitation in rats.

Very early environmental enrichment protects against apoptosis and improves functional recovery from hypoxic-ischemic brain injury

Appropriate rehabilitation of stroke patients at a very early phase results in favorable outcomes. However, the optimal strategy for very early rehabilitation is at present unclear due to the limited knowledge on the effects of very early initiation of rehabilitation based on voluntary exercise (VE). Environmental enrichment (EE) is a therapeutic paradigm for laboratory animals that involves complex combinations of physical, cognitive, and social stimuli, as well as VE. Few studies delineated the effect of EE on apoptosis in very early stroke in an experimental model. Although a minimal benefit of early rehabilitation in stroke models has been claimed in previous studies, these were based on a forced exercise paradigm. The aim of this study is to determine whether very early exposure to EE can effectively regulate Fas/FasL-mediated apoptosis following hypoxic-ischemic (HI) brain injury and improve neurobehavioral function. C57Bl/6 mice were housed for 2 weeks in either cages with EE or standard cages (SC) 3 h or 72 h after HI brain injury. Very early exposure to EE was associated with greater improvement in motor function and cognitive ability, reduced volume of the infarcted area, decreased mitochondria-mediated apoptosis, and decreased oxidative stress. Very early exposure to EE significantly downregulated Fas/FasL-mediated apoptosis, decreased expression of Fas, Fas-associated death domain, cleaved caspase-8/caspase-8, cleaved caspase-3/caspase-3, as well as Bax and Bcl-2, in the cerebral cortex and the hippocampus. Delayed exposure to EE, on the other hand, failed to inhibit the extrinsic pathway of apoptosis. This study demonstrates that very early exposure to EE is a potentially useful therapeutic translation for stroke rehabilitation through effective inhibition of the extrinsic and intrinsic apoptotic pathways.

Exercise postconditioning reduces ischemic injury via suppression of cerebral gluconeogenesis in rats

Pre-stroke exercise conditioning reduces neurovascular injury and improves functional outcomes after stroke. The goal of this study was to explore if post-stroke exercise conditioning (PostE) reduced brain injury and whether it was associated with the regulation of gluconeogenesis. Adult rats received 2 h of middle cerebral artery (MCA) occlusion, followed by 24 h of reperfusion. Treadmill activity was then initiated 24 h after reperfusion for PostE. The severity of the brain damage was determined by infarct volume, apoptotic cell death, and neurological deficit at one and three days after reperfusion. We measured gluconeogenesis including oxaloacetate (OAA), phosphoenolpyruvate (PEP), pyruvic acid, lactate, ROS, and glucose via ELISA, as well as the location and expression of the key enzyme phosphoenolpyruvate carboxykinase (PCK)-1/2 via immunofluorescence. We also determined upstream pathways including forkhead transcription factor (FoxO1), p-FoxO1, 3-kinase (PI3K)/Akt, and p-PI3K/Akt via Western blot. Additionally, the cytoplasmic expression of p-FoxO1 was detected by immunofluorescence. Compared to non-exercise control, PostE (*p < .05) decreased brain infarct volumes, neurological deficits, and cell death at one and three days. PostE groups (*p < .05) saw increases in OAA and decreases in PEP, pyruvic acid, lactate, ROS, glucose levels, and tissue PCKs expression on both days. PCK-1/2 expressions were also significantly (*p < .05) suppressed by the exercise setting. Additionally, phosphorylated PI3K, AKT, and FoxO1 protein expression were significantly induced by PostE at one and three days (*p < .05). In this study, PostE reduced brain injury after stroke, in association with activated PI3K/AKT/FoxO1 signaling, and inhibited gluconeogenesis. These results suggest the involvement of FoxO1 regulation of gluconeogenesis underlying post-stroke neuroprotection.

Effects of Stroke Lesions and Timing of Rehabilitation on the Compensatory Movement Patterns During Stroke Recovery

OBJECTIVES

The aims of this study were to distinguish between behavioral compensation and behavioral recovery and to determine the role of stroke lesions and the optimal timing of rehabilitation in true recovery.

DESIGN

Single pellet reaching test has been performed to analyze both quantitative and qualitative measures of forelimb function in a stroke animal model with lesions in the motor cortex, somatosensory cortex, or sensorimotor cortex. The four gestures of compensatory movement patterns that comprised a reach were head lift, limb withdrawal, pellet chasing, and phantom grasp.

RESULTS

Functional recovery improved in all the stroke groups after rehabilitation ( P < 0.001). However, the compensatory movement patterns of the motor cortex and somatosensory cortex stroke groups initially increased and subsequently decreased ( P = 0.0054), whereas those of the sensorimotor cortex stroke group increased and persisted ( P = 0.0063). In the sensorimotor cortex stroke group, compensatory movement patterns significantly decreased when training was initiated 5 and 14 days after stroke ( P = 0.0083, P = 0.0226, respectively), while they increased and persisted when training was initiated 1 day after stroke.

CONCLUSIONS

These findings suggest that true recovery by task-specific training after stroke depends, probably, on the lesion size and the timing of rehabilitation.

Activation of BDNF- and VEGF-mediated Neuroprotection by Treadmill Exercise Training in Experimental Stroke

Early treatment of ischemic stroke is one of the most effective ways to reduce brains' cell death and promote functional recovery. This study was designed to examine the effect of aerobic exercise on post ischemia/reperfusion injury on concentration and expression of brain-derived neurotrophic factor (BDNF) and vascular endothelial growth factor (VEGF) after inducing a neuronal loss in CA1 region of hippocampus in Male Wistar rats. Three experimental groups including sham(S), ischemia/reperfusion-control (IRC) and ischemia/reperfusion exercise (IRE) were used for this purpose. The rats in the IRE group received a bilateral carotid artery occlusion treatment. They ran for 45 minutes on a treadmill five days per week for eight consecutive weeks. Cresyl violet (Nissl), Hematoxylin (H & E) and Eosin staining procedure were used to determine the extent of damage. A ladder rung walking task was used to assess the functional impairments and recovery after the ischemic lesion. ELISA and immunohistochemistry method were employed to measure BDNF and VEGF protein expressions. The result showed that the brain ischemia/reperfusion condition increased the cell death in hippocampal CA1 neurons and impaired motor performance on the ladder rung task whereas the aerobic exercise program significantly decreased the brain cell's death and improved motor skill performance. It was concluded that ischemic brain lesion decreased the BDNF and VEGF expression. It seems that the aerobic exercise following the ischemia/reperfusion potentially promotes neuroprotective mechanisms and neuronal repair and survival mediated partly by BDNF and other pathways.

Effect of exercise from a very early stage after intracerebral hemorrhage on microglial and macrophage reactivity states in rats

OBJECTIVE

This study investigated the effects of exercise, starting very early after intracerebral hemorrhage (ICH), on microglia and macrophages in a rat model. Collagenase solution was injected into the left striatum to induce ICH.

METHODS

Rats were randomly assigned to receive placebo surgery without exercise (sham surgery), ICH without exercise (ICH), or ICH with very early exercise (ICH + VET). The ICH + VET group was subjected to treadmill running 6 h, 24 h, and days 2-6 after ICH. Motor function assessment was performed using the ladder test and rotarod test 3 h, 25 h, and 7 days after ICH. Postexercise brain tissue was collected on day 8 after surgery to investigate the lesion volume. Very early exercise temporarily worsened motor dysfunction. The protein expression levels of the macrophage and microglial markers CD80, CD163, and TMEM119 were analyzed 6 h, 24 h, and 8 days after ICH. Protein analysis of NeuN, GFAP, and PSD95 was also performed on day 8 after ICH.

RESULTS

There was no significant difference in lesion volume between the ICH and ICH + VET groups on day 8 after ICH. Exercise from very early stage prevented elevated CD163 protein expression.

CONCLUSION

Very early exercise may inhibit the activation of anti-inflammatory-associated macrophages/microglia.

Neuroprotective Effect of Physical Activity in Ischemic Stroke: Focus on the Neurovascular Unit

Cerebral ischemia is one of the major diseases associated with death or disability among patients. To date, there is a lack of effective treatments, with the exception of thrombolytic therapy that can be administered during the acute phase of ischemic stroke. Cerebral ischemia can cause a variety of pathological changes, including microvascular basal membrane matrix, endothelial cell activation, and astrocyte adhesion, which may affect signal transduction between the microvessels and neurons. Therefore, researchers put forward the concept of neurovascular unit, including neurons, axons, astrocytes, microvasculature (including endothelial cells, basal membrane matrix, and pericyte), and oligodendrocytes. Numerous studies have demonstrated that exercise can produce protective effects in cerebral ischemia, and that exercise may protect the integrity of the blood-brain barrier, promote neovascularization, reduce neuronal apoptosis, and eventually lead to an improvement in neurological function after cerebral ischemia. In this review, we summarized the potential mechanisms on the effect of exercise on cerebral ischemia, by mainly focusing on the neurovascular unit, with the aim of providing a novel therapeutic strategy for future treatment of cerebral ischemia.

Associations Between Time After Stroke and Exercise Training Outcomes: A Meta-Regression Analysis

Background Knowledge gaps exist regarding the effect of time elapsed after stroke on the effectiveness of exercise training interventions, offering incomplete guidance to clinicians. Methods and Results To determine the associations between time after stroke and 6-minute walk distance, 10-meter walk time, cardiorespiratory fitness and balance (Berg Balance Scale score [BBS]) in exercise training interventions, relevant studies in post-stroke populations were identified by systematic review. Time after stroke as continuous or dichotomized (≤3 months versus >3 months, and ≤6 months versus >6 months) variables and weighted mean differences in postintervention outcomes were examined in meta-regression analyses adjusted for study baseline mean values (pre-post comparisons) or baseline mean values and baseline control-intervention differences (controlled comparisons). Secondary models were adjusted additionally for mean age, sex, and aerobic exercise intensity, dose, and modality. We included 148 studies. Earlier exercise training initiation was associated with larger pre-post differences in mobility; studies initiated ≤3 months versus >3 months after stroke were associated with larger differences (weighted mean differences [95% confidence interval]) in 6-minute walk distance (36.3 meters; 95% CI, 14.2-58.5), comfortable 10-meter walk time (0.13 m/s; 95% CI, 0.06-0.19) and fast 10-meter walk time (0.16 m/s; 95% CI, 0.03-0.3), in fully adjusted models. Initiation ≤3 months versus >3 months was not associated with cardiorespiratory fitness but was associated with a higher but not clinically important Berg Balance Scale score difference (2.9 points; 95% CI, 0.41-5.5). In exercise training versus control studies, initiation ≤3 months was associated with a greater difference in only postintervention 6-minute walk distance (baseline-adjusted 27.3 meters; 95% CI, 6.1-48.5; fully adjusted, 24.9 meters; 95% CI, 0.82-49.1; a similar association was seen for ≤6 months versus >6 months after stroke (fully adjusted, 26.6 meters; 95% CI, 2.6-50.6). Conclusions There may be a clinically meaningful benefit to mobility outcomes when exercise is initiated within 3 months and up to 6 months after stroke.

Neuroplastic Effect of Exercise Through Astrocytes Activation and Cellular Crosstalk

Physical exercise is an effective therapy for neurorehabilitation. Exercise has been shown to induce remodeling and proliferation of astrocyte. Astrocytes potentially affect the recruitment and function of neurons; they could intensify responses of neurons and bring more neurons for the process of neuroplasticity. Interactions between astrocytes, microglia and neurons modulate neuroplasticity and, subsequently, neural circuit function. These cellular interactions promote the number and function of synapses, neurogenesis, and cerebrovascular remodeling. However, the roles and crosstalk of astrocytes with neurons and microglia and any subsequent neuroplastic effects have not been studied extensively in exercise-induced settings. This article discusses the impact of physical exercise on astrocyte proliferation and highlights the interplay between astrocytes, microglia and neurons. The crosstalk between these cells may enhance neuroplasticity, leading to the neuroplastic effects of exercise.

Chlorpromazine and promethazine reduces Brain injury through RIP1-RIP3 regulated activation of NLRP3 inflammasome following ischemic stroke

Objectives: Stroke is an important cause of death and disability. Recent evidence suggests that post-stroke inflammation is an important factor in stroke pathology and a root cause of its lasting consequences. Phenothiazine drugs, like chlorpromazine and promethazine (C + P), induce hypothermia and have been shown to play a major role in neuroprotection. In the present study, we investigated this neuroprotective mechanism by assessing the anti-inflammatory effect of these drugs.Methods: Adult Sprague-Dawley rats underwent 2 h of middle cerebral artery occlusion (MCAO) followed by 6 or 24 h of reperfusion, with or without C + P (8 mg/kg). Infarct volumes, neurological deficits, along with mRNA and protein quantities of receptor-interacting protein 1 (RIP1), receptor-interacting protein 3 (RIP3), NLRPyrin domain containing 3 (NLRP3), and interleukin-1β (IL-1β) were assessed, as well as the infiltration of neutrophils and macrophages.Results: C + P induced hypothermia that significantly reduced RIP1, RIP3, NLRP3 and IL-1β expression, infarction, and immune cell infiltration, while C + P treatment with temperature control at 37°C induced lesser effect.Conclusion: These findings suggest that the anti-inflammatory effect of C + P may be dependent on drug-induced hypothermia and regulation of the NLRP3 inflammasome via the RIP1/RIP3 complex. Future investigations are needed regarding C + P as potential treatment of ischemic stroke.

Remote ischemic conditioning with exercise (RICE) promotes functional rehabilitation following ischemic stroke

Objective: Exercise is an essential rehabilitative strategy after stroke butits implementation is limited as its very early use can exacerbate damage and is restricted by patient disability. Remote Ischemic Conditioning (RIC) is a safe alternative for post-stroke neuroprotetion. The present study investigated the neurorehabilitative benefits of early RIC followed by exercise (RICE) therapy.Methods: 48 adult male Sprague-Dawley rats were divided into groups: 1) sham, 2) stroke, 3) stroke with RICE at day 3 (RIC 6 hours after reperfusion followed by exercise days 3 to 28), 4) stroke with exercise at day 3 (exercise days 3 to 28), and 5) stroke with RICE at day 1 (RIC 6 hours after reperfusion followed by exercise days 1 to 28), 6) stroke with exercise at day 1 (exercise days 1 to 28 after reperfusion). Long-term functional outcomes were determined by grid walk, rota-rod, adhesive tape touch, and Morris water maze. Levels of mRNA and proteins of neuroplasticity, synaptogenesis, and angiogenesis, were determined.Results: As compared to exercise only, animals that underwent RICE had significant improvements in functional outcomes after stroke. These improvements were most significant in groups that had the later initiation of exercise. In addition, all treatment groups showed significant increases in mRNA and protein expression of the target molecules for neuroplasticity, synaptogenesis, and angiogenesis, while further significant increases were observed after RICE following ischemic stroke.Conclusions: RICE, a novel therapy that supplements RIC prior to exercise, is superiorly effective in inducing rehabilitation after stroke as compared to the traditional exercise monotherapy rehabilitation in rats with ischemic brain injury.

Very Early Exercise Rehabilitation After Intracerebral Hemorrhage Promotes Inflammation in the Brain

BACKGROUND

Very early exercise has been reported to exacerbate motor dysfunction; however, its mechanism is largely unknown.

OBJECTIVE

This study examined the effect of very early exercise on motor recovery and associated brain damage following intracerebral hemorrhage (ICH) in rats.

METHODS

Collagenase solution was injected into the left striatum to induce ICH. Rats were randomly assigned to receive placebo surgery without exercise (SHAM) or ICH without (ICH) or with very early exercise within 24 hours of surgery (ICH+VET). We observed sensorimotor behaviors before surgery, and after surgery preexercise and postexercise. Postexercise brain tissue was collected 27 hours after surgery to investigate the hematoma area, brain edema, and Il1b, Tgfb1, and Igf1 mRNA levels in the striatum and sensorimotor cortex using real-time reverse transcription polymerase chain reaction. NeuN, PSD95, and GFAP protein expression was analyzed by Western blotting.

RESULTS

We observed significantly increased skillful sensorimotor impairment in the horizontal ladder test and significantly higher Il1b mRNA levels in the striatum of the ICH+VET group compared with the ICH group. NeuN protein expression was significantly reduced in both brain regions of the ICH+VET group compared with the SHAM group.

CONCLUSION

Our results suggest that very early exercise may be associated with an exacerbation of motor dysfunction because of increased neuronal death and region-specific changes in inflammatory factors. These results indicate that implementing exercise within 24 hours after ICH should be performed with caution.

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.

Forced forelimb use following stroke enhances oligodendrogenesis and functional recovery in the rat

Forced limb use, which forces the use of the impaired arm following stroke, improves functional recovery. The study was designed to investigate the mechanisms of recovery underlying forced impaired limbuse. Furthermore, forced unimpaired arm use was also performed in order to explore its effect on functional behavior. We hypothesized that forced forelimb use could improve functional recovery in rats that have had an experimentally induced ischemic stroke, through promoting the recruitment and differentiation of the oligodendrocyte progenitor cells (OPCs). Indeed the proliferation of Olig2 and NG2 positive cells, as well as the expression of myelin basic protein (MBP)were increased in the perilesional striatum, whereas quantitative changes of Olig2+ and NG2+ oligodendrocyte progenitor cells was not observed in the subventricular zone. Through comparing rats forced to rely on affected or unaffected forelimb, the results demonstrated that forced impaired limb use boosted functional recovery. At the same time forced unimpaired limb use deteriorated limb movement of injured side. In addition, the expression of NogoA is reduced, when the injured limb was used more, suggesting that it played a role in the repair of white matter.

Hypoxia Inducible Factor-1α (HIF-1α) Mediates NLRP3 Inflammasome-Dependent-Pyroptotic and Apoptotic Cell Death Following Ischemic Stroke

Stroke is a major cause of death and long-term disability. Recent evidence suggests that hypoxia-inducible factor 1α (HIF-1α), a transcription factor that regulates oxygen levels, plays a key role in neurological outcomes after ischemic stroke. Accordingly, we investigated the mechanism of HIF-1α on pyroptotic and apoptotic cells during ischemia/reperfusion (I/R). Adult Sprague-Dawley rats underwent 2 h of middle cerebral artery occlusion (MCAO). The rats were then exposed to 6 or 24 h of reperfusion, with or without YC-1 (HIF-1α inhibitor, 5 mg/kg). Infarct volumes, along with mRNA and protein quantities of HIF-1α, NLRP3, IL-1β, IL-18, Caspase-1, and co-localization of HIF-1α, and NLRP3, were assessed. We measured apoptotic and pyroptotic cell death, gasdermin D (GSDMD) activation and lactate dehydrogenase (LDH) activity, and the infiltration of neutrophils and macrophages after ischemic stroke. HIF-1α mRNA and NLRP3 inflammasome components were increased after 24 h of reperfusion. YC-1 significantly reduced the mRNA and protein expression of NLRP3, IL-1β, IL-18, and caspase-1; significantly decreased infarction and pyroptotic cell death after 24 h of reperfusion; attenuated the neuroinflammatory response by reducing infiltration of CD68- and MPO-positive cells after 24 h of reperfusion; and reduced apoptotic cell death following ischemic stroke. We found that HIF-1α likely regulates inflammatory responses through the NLRP3 inflammasome complex, thus influencing both apoptotic and pyroptotic cell death after stroke. These findings suggest that future investigations are needed regarding HIF-1α and its role as a potential molecular target in the treatment of acute ischemic stroke.

In Search of a Dose: The Functional and Molecular Effects of Exercise on Post-stroke Rehabilitation in Rats

Although physical exercise has been demonstrated to augment recovery of the post-stroke brain, the question of what level of exercise intensity optimizes neurological outcomes of post-stroke rehabilitation remains unsettled. In this study, we aim to clarify the mechanisms underlying the intensity-dependent effect of exercise on neurologic function, and thereby to help direct the clinical application of exercise-based neurorehabilitation. To do this, we used a well-established rat model of ischemic stroke consisting of cerebral ischemia induction through middle cerebral artery occlusion (MCAO). Ischemic rats were subsequently assigned either to a control group entailing post-stroke rest or to one of two exercise groups distinguished by the intensity of their accompanying treadmill regimens. After 24 h of reperfusion, exercise was initiated. Infarct volume, apoptotic cell death, and neurological defects were quantified in all groups at 3 days, and motor and cognitive functions were tracked up to day-28. Additionally, Western blotting was used to assess the influence of our interventions on several proteins related to synaptogenesis and neuroplasticity (growth-associated protein 43, a microtubule-associated protein, postsynaptic density-95, synapsin I, hypoxia-inducible factor-1α, brain-derived neurotrophic factor, nerve growth factor, tyrosine kinase B, and cAMP response element-binding protein). Our results were in equal parts encouraging and surprising. Both mild and intense exercise significantly decreased infarct volume, cell death, and neurological deficits. Motor and cognitive function, as determined using an array of tests such as beam balance, forelimb placing, and the Morris water maze, were also significantly improved by both exercise protocols. Interestingly, while an obvious enhancement of neuroplasticity proteins was shown in both exercise groups, mild exercise rats demonstrated a stronger effect on the expressions of Tau (p < 0.01), brain-derived neurotrophic factor (p < 0.01), and tyrosine kinase B (p < 0.05). These findings contribute to the growing body of literature regarding the positive effects of both mild and intense long-term treadmill exercise on brain injury, functional outcome, and neuroplasticity. Additionally, the results may provide a base for our future study regarding the regulation of HIF-1α on the BDNF/TrkB/CREB pathway in the biochemical processes underlying post-stroke synaptic plasticity.

Prevalence of Low Plasma Vitamin B1 in the Stroke Population Admitted to Acute Inpatient Rehabilitation

OBJECTIVE

To determine the prevalence of vitamin B1 (VitB1) deficiency in the stroke population admitted to acute inpatient rehabilitation.

DESIGN

Retrospective cohort study.

SETTING

Acute inpatient rehabilitation facility at an academic medical center.

PARTICIPANTS

119 consecutive stroke patients admitted to stroke service from 1 January 2018 to 31 December 2018.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Plasma VitB1 level.

RESULTS

There were 17 patients (14%; 95% CI 9-22%) with low VitB1 with a range of 2-3 nmol/L, an additional 58 (49%; CI 40-58%) patients had normal low VitB1 with a range of 4-9 nmol/L, twenty-five patients (21%; CI 15-29%) had normal high VitB1 with a range of 10-15 nmol/L, and nineteen patients (16%; CI 10-24%) had high VitB1 with a range of 16-43 nmol/L.

CONCLUSIONS

In this cohort of patients admitted to the stroke service at an acute rehabilitation facility, there is evidence of thiamine deficiency. Moreover, the data suggest that there is inadequate acute intake of VitB1. Given the role of thiamine deficiency in neurologic function, further study of the role of thiamine optimization in the acute stroke rehabilitation population is warranted.

Modified constraint-induced movement therapy alters synaptic plasticity of rat contralateral hippocampus following middle cerebral artery occlusion

Modified constraint-induced movement therapy is an effective treatment for neurological and motor impairments in patients with stroke by increasing the use of their affected limb and limiting the contralateral limb. However, the molecular mechanism underlying its efficacy remains unclear. In this study, a middle cerebral artery occlusion (MCAO) rat model was produced by the suture method. Rats received modified constraint-induced movement therapy 1 hour a day for 14 consecutive days, starting from the 7^th day after middle cerebral artery occlusion. Day 1 of treatment lasted for 10 minutes at 2 r/min, day 2 for 20 minutes at 2 r/min, and from day 3 onward for 20 minutes at 4 r/min. CatWalk gait analysis, adhesive removal test, and Y-maze test were used to investigate motor function, sensory function as well as cognitive function in rodent animals from the 1^st day before MCAO to the 21^st day after MCAO. On the 21^st day after MCAO, the neurotransmitter receptor-related genes from both contralateral and ipsilateral hippocampi were tested by micro-array and then verified by western blot assay. The glutamate related receptor was shown by transmission electron microscopy and the glutamate content was determined by high-performance liquid chromatography. The results of behavior tests showed that modified constraint-induced movement therapy promoted motor and sensory functional recovery in the middle cerebral artery-occluded rats, but had no effect on cognitive function. The modified constraint-induced movement therapy upregulated the expression of glutamate ionotropic receptor AMPA type subunit 3 (Gria3) in the hippocampus and downregulated the expression of the beta3-adrenergic receptor gene Adrb3 and arginine vasopressin receptor 1A, Avpr1a in the middle cerebral artery-occluded rats. In the ipsilateral hippocampus, only Adra2a was downregulated, and there was no significant change in Gria3. Transmission electron microscopy revealed a denser distribution the more distribution of postsynaptic glutamate receptor 2/3, which is an α-amino-3-hydroxy-5-methyl-4-isoxazole-propionic acid receptor, within 240 nm of the postsynaptic density in the contralateral cornu ammonis 3 region. The size and distribution of the synaptic vesicles within 100 nm of the presynaptic active zone were unchanged. Western blot analysis showed that modified constraint-induced movement therapy also increased the expression of glutamate receptor 2/3 and brain-derived neurotrophic factor in the hippocampus of rats with middle cerebral artery occlusion, but had no effect on Synapsin I levels. Besides, we also found modified constraint-induced movement therapy effectively reduced glutamate content in the contralateral hippocampus. This study demonstrated that modified constraint-induced movement therapy is an effective rehabilitation therapy in middle cerebral artery-occluded rats, and suggests that these positive effects occur via the upregulation of the postsynaptic membrane α-amino-3-hydroxy-5-methyl-4-isoxazole-propionic acid receptor expression. This study was approved by the Institutional Animal Care and Use Committee of Fudan University, China (approval No. 201802173S) on March 3, 2018.

Aerobic Training and Mobilization Early Post-stroke: Cautions and Considerations

Knowledge gaps exist in how we implement aerobic exercise programs during the early phases post-stroke. Therefore, the objective of this review was to provide evidence-based guidelines for pre-participation screening, mobilization, and aerobic exercise training in the hyper-acute and acute phases post-stroke. In reviewing the literature to determine safe timelines of when to initiate exercise and mobilization we considered the following factors: arterial blood pressure dysregulation, cardiac complications, blood-brain barrier disruption, hemorrhagic stroke transformation, and ischemic penumbra viability. These stroke-related impairments could intensify with inappropriate mobilization/aerobic exercise, hence we deemed the integrity of cerebral autoregulation to be an essential physiological consideration to protect the brain when progressing exercise intensity. Pre-participation screening criteria are proposed and countermeasures to protect the brain from potentially adverse circulatory effects before, during, and following mobilization/exercise sessions are introduced. For example, prolonged periods of standing and static postures before and after mobilization/aerobic exercise may elicit blood pooling and/or trigger coagulation cascades and/or cerebral hypoperfusion. Countermeasures such as avoiding prolonged standing or incorporating periodic lower limb movement to activate the venous muscle pump could counteract blood pooling after an exercise session, minimize activation of the coagulation cascade, and mitigate potential cerebral hypoperfusion. We discuss patient safety in light of the complex nature of stroke presentations (i.e., type, severity, and etiology), medical history, comorbidities such as diabetes, cardiac manifestations, medications, and complications such as anemia and dehydration. The guidelines are easily incorporated into the care model, are low-risk, and use minimal resources. These and other strategies represent opportunities for improving the safety of the activity regimen offered to those in the early phases post-stroke. The timeline for initiating and progressing exercise/mobilization parameters are contingent on recovery stages both from neurobiological and cardiovascular perspectives, which to this point have not been specifically considered in practice. This review includes tailored exercise and mobilization prescription strategies and precautions that are not resource intensive and prioritize safety in stroke recovery.

Aggravating effects of treadmill exercises during the early-onset period in a rat traumatic brain injury model: When should rehabilitation exercises be initiated?

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A traumatic brain injury model was prepared in rats by stab wounding.

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Rats were forced to walk slowly on a treadmill once for 10 min at 24 h or 48 h after wounding.

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Exercise, particularly at 24 h, aggravated motor impairment while increasing the expression of proinflammatory factors.

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Exercise for rehabilitation should be initiated after 48 h of severe brain injury onset.

Physical exercise is one of the best interventions for improving traumatic brain injury (TBI) outcomes. However, an argument has been raised regarding the timing at which physical exercise should be initiated. In this study, male Wistar rats were subjected to stab wounding of the right hemisphere to develop a TBI model and were forced to walk once on a treadmill at a 5-m/min pace at 24 h or 48 h after TBI for 10 min. Injured brain tissue was dissected after TBI to evaluate the effects of exercise. Behavioral abnormalities and motor impairment were assessed by various behavioral tests between 2 and 3 weeks after TBI. Exercise did not affect the circulating corticosterone levels and the weight of the adrenal glands. Exercise particularly that at 24 h, worsened the motor impairment of the left forelimbs. Quantitative reverse-transcription polymerase chain reaction showed that exercise at 24 h increased proinflammatory cytokines and chemokines on the third day while suppressing the proinflammatory reactions on the fourth day. Exercise at both time points decreased expression of transforming growth factor (TGF) β1 and its receptor TGFβR1. Exercise at 24 h increased phosphorylation of IκB kinase on the fourth day, which may be correlated with the decreased effects of TGFβ1. Even a low-intensity exercise activity could cause deleterious effects when it is initiated within 48 h after the onset of severe TBI, probably because of the resulting proinflammatory effects. Therefore, rehabilitation exercise programs should be initiated after 48 h of TBI onset.

A brief physical activity protects against ischemic stroke

With restricted therapeutic opportunities, stroke remains a relevant, critical disease necessitating study. Due to the unique aspect of ischemic strokes, finding approaches to maintain the vigor of the cerebral vasculature, such as increased angiogenesis, may protect against stroke. Ischemic strokes are caused by disruptions in blood movement in the brain, resulting in a torrent of harmful cerebrovasculature modifications. In an investigation by Pianta et al., Sprague-Dawley rats have been separated into those that undergo exercise prior to middle cerebral artery occlusion (MCAO) and those that were not exposed to physical activity preceding MCAO. The outcomes and results of the current study gave new insights into the capacity of exercise to help prevent ischemic strokes or mitigate poststroke effects. The data collected from the study suggested that rats that went through a short bout of exercise before MCAO presented superior motor performance, more active cells in the peri-infarct region, and reduced infarct sizes. When compared to the control group, the rats that went through exercise also had heightened angiogenesis and improved neuroprotection. Thus, a brief bout of physical activity preceding a stroke may provide neuroprotection by enhancing the strength of the cerebrovasculature in the brain. This notion that even an instant of physical exercise before a stroke is induced can help dampen the effects of ischemic stroke, which could lead to future techniques in preventing the ischemic stroke so that it never happens at all.

Very Early Initiation Reduces Benefits of Poststroke Rehabilitation Despite Increased Corticospinal Projections

Background. Although the effect of rehabilitation is influenced by aspects of the training protocol, such as initiation time and intensity of training, it is unclear whether training protocol modifications affect the corticospinal projections. Objective. The present study was designed to investigate how modification of initiation time (time-dependency) and affected forelimb use (use-dependency) influence the effects of rehabilitation on functional recovery and corticospinal projections. Methods. The time-dependency of rehabilitation was investigated in rats forced to use their impaired forelimb immediately, at 1 day, and 4 days after photothrombotic stroke. The use-dependency of rehabilitation was investigated by comparing rats with affected forelimb immobilization (forced nonuse), unaffected forelimb immobilization (forced use), and a combination of forced use and skilled forelimb training beginning at 4 days after stroke. Results. Although forced use beginning 1 day or 4 days after stroke caused significant functional improvement, immediate forced limb use caused no functional improvement. On the other hand, a combination of forced use and skilled forelimb training boosted functional recovery in multiple tasks compared to simple forced use treatment. Histological examination showed that no treatment caused brain damage. However, a retrograde tracer study revealed that immediate forced use and combination training, including forced use and skilled forelimb training, increased corticospinal projections from the contralesional and ipsilesional motor cortex, respectively. Conclusions. These results indicate that although both very early initiation time and enhanced skilled forelimb use increased corticospinal projections, premature initiation time hampers the functional improvement induced by poststroke rehabilitation.

A Short Bout of Exercise Prior to Stroke Improves Functional Outcomes by Enhancing Angiogenesis

Stroke remains a significant unmet clinical need with limited therapeutic options. The peculiar feature of ischemic stroke is the interruption in brain circulation, resulting in a cascade of detrimental cerebrovasculature alterations. Treatment strategies designed to maintain potency of the cerebrovasculature may protect against stroke. The present study assessed the effects of short bouts of exercise prior to stroke induction and characterized cerebral blood flow and motor functions in vivo. Adult Sprague-Dawley rats were exposed to a single short bout of exercise (30-min or 60-min forced running wheel) then subjected to transient middle cerebral artery occlusion (MCAO). Non-exercise stroke rats served as controls while non-stroke rats represented shams. Cerebral blood flow (CBF) was evaluated by laser Doppler at baseline (prior to MCAO), during MCAO, and during reperfusion. Behavioral tests using the elevated body swing test was conducted at baseline, day 0 (day of stroke), and at days 1 and 3 after stroke. Animals that received exercise displayed typical alterations in CBF after stroke, but exhibited improved motor performance compared to non-exercise rats. Exercised stroke rats showed a reduction in infarct size and an increased number of surviving cells in the peri-infarct area, with a trend towards prolonged duration of the exercise. Immunofluorescence staining and Western blot analysis of the peri-infarct area revealed increased levels of endothelial markers/angiogenesis markers, VEGF, VEGFR-2, and Ang-2, and endothelial progenitor cell marker CD34+ in exercise groups compared with the controls. These results demonstrated that prophylactic exercise affords neuroprotection possibly by improving cerebrovascular potency.

Constraint-induced movement therapy improves efficacy of task-specific training after severe cortical stroke depending on the ipsilesional corticospinal projections

Descending spinal pathways (corticospinal, rubrospinal, and reticulospinal) are believed to contribute to functional recovery resulting from rehabilitative training after stroke. However, the contribution of each pathway remains unclear. In the current study, we investigated rehabilitation-induced functional recovery and remodelling of the descending spinal pathways after severe cortical stroke in rats followed by 3 weeks of various rehabilitation [constraint-induced movement therapy (CIMT), skilled forelimb reaching, rotarod, and treadmill exercise]. Following photothrombotic stroke, 96% of corticospinal neurons in the ipsilesional motor cortex were destroyed. Despite the preservation of 82% of total spinal projection neurons (e.g. rubrospinal and reticulospinal projection neurons), rats showed persistent and severe disability, especially in skilled motor function. In this severe stroke model, only CIMT promoted functional recovery, associated with increased corticospinal projections from the peri-infarct motor cortex. Rehabilitation-induced recovery was reversed when the restored corticospinal neurons were destroyed by a second stroke. These data indicate that training-induced functional recovery is dependent on ipsilesional corticospinal projections, which highlights the importance of using strategies to enhance survival, axonal remodelling, or regeneration of corticospinal neurons to effectively restore function in severely affected stroke patients.

Combining robotic training and inactivation of the healthy hemisphere restores pre-stroke motor patterns in mice

Focal cortical stroke often leads to persistent motor deficits, prompting the need for more effective interventions. The efficacy of rehabilitation can be increased by ‘plasticity-stimulating’ treatments that enhance experience-dependent modifications in spared areas. Transcallosal pathways represent a promising therapeutic target, but their role in post-stroke recovery remains controversial. Here, we demonstrate that the contralesional cortex exerts an enhanced interhemispheric inhibition over the perilesional tissue after focal cortical stroke in mouse forelimb motor cortex. Accordingly, we designed a rehabilitation protocol combining intensive, repeatable exercises on a robotic platform with reversible inactivation of the contralesional cortex. This treatment promoted recovery in general motor tests and in manual dexterity with remarkable restoration of pre-lesion movement patterns, evaluated by kinematic analysis. Recovery was accompanied by a reduction of transcallosal inhibition and ‘plasticity brakes’ over the perilesional tissue. Our data support the use of combinatorial clinical therapies exploiting robotic devices and modulation of interhemispheric connectivity.