Effects of enriched environment on microglia and functional white matter recovery in rats with post stroke cognitive impairment

High-Frequency repetitive transcranial magnetic stimulation enhances white matter integrity in a rat model of ischemic stroke: A diffusion tensor imaging study using tract-based spatial statistics

Ischemic stroke leads to white matter damage and neurological deficits. Previous studies have revealed that high-frequency repetitive transcranial magnetic stimulation (HF-rTMS) has beneficial effects on white matter reorganization and neurological recovery after stroke. However, the characteristics of poststroke white matter repair after treatment with HF-rTMS remain unclear. Therefore, this study used diffusion tensor imaging (DTI) to investigate the impact of HF-rTMS on white matter integrity following middle cerebral artery occlusion (MCAO) in a rat model. The modified neurological severity score (mNSS) and T2-weighted imaging data were used to assess neurological function and infarct size. We used a tract-based spatial statistics (TBSS) approach to analyze changes in fractional anisotropy (FA) across various white matter tracts. Furthermore, we performed Luxol fast blue (LFB) staining and transmission electron microscopy (TEM) to detect white matter and myelin damage. The results revealed that compared with the tMCAO group, the tMCAO+rTMS group presented a significant decrease in infarct size and the mNSS, as well as significantly greater FA values, mostly in the left external capsule, left internal capsule, left optic tract, left deep cerebral white matter, left stria terminalis and right external capsule. The LFB staining and electron microscopy results are consistent with the DTI results. These findings suggest that HF-rTMS contributes to the recovery of white matter integrity and neurological function. This study underscores the importance of HF-rTMS as a noninvasive intervention for enhancing poststroke neurological recovery by improving white matter integrity.

Enriched environment alleviates NLRP3 inflammasome mediated neuroinflammation in diabetes complicated with depression rats

Depression is a serious and common complication of diabetes, with a well-established link between the two conditions. Recent studies indicate that activation of the NLRP3 inflammasome in hippocampal microglia plays a key role in the pathogenesis of diabetes complicated with depression (DD). While environmental enrichment (EE) has demonstrated significant anti-neuroinflammatory effects, its potential to alleviate neuroinflammation specifically induced by DD remains unclear. The DD rat model was established using a combination of a high-fat diet, streptozotocin injection, and chronic unpredictable mild stress. The effects of EE on NLRP3 inflammasome activation in the hippocampal microglia of DD rats were examined through a series of behavioral tests (open field test, forced swim test, and elevated plus maze), along with enzyme-linked immunosorbent assays, hematoxylin and eosin staining, TdT-mediated dUTP nick-end labeling staining, Western blot analysis, and immunofluorescence. Compared to the control group, DD rats exhibited impaired glucose metabolism and increased depressive-like behaviors, alongside hippocampal neuronal damage and elevated apoptosis rates. Activation of the NLRP3 inflammasome in hippocampal microglia was observed, with upregulation of the NLRP3 signaling pathway and inhibition of the PI3K/AKT signaling pathway. EE significantly mitigated these effects, reducing hippocampal neuroinflammation and alleviating depressive behaviors in DD rats. Neuroinflammation in the hippocampus is a key mechanism underlying the pathogenesis of DD. This study demonstrated that EE reduces neuroinflammation, likely by inhibiting the activation of the NLRP3 inflammasome in hippocampal microglia.

Environmental enrichment: a neurostimulatory approach to aging and ischemic stroke recovery and rehabilitation

Environmental enrichment (EE) represents a robust experimental framework exploring the intricate interplay between genes and the environment in shaping brain development and function. EE is recognized as a non-invasive intervention, easily translatable to elderly human cohorts, and extrapolated from research on animal aging models. Age is the most important risk factor for ischemic stroke. Research indicates that EE, characterized by increased sensory, cognitive, and social stimulation, leads to structural changes in the brain, such as enhanced dendritic complexity and synaptic density, particularly in the hippocampus and cortex. Tailored EE interventions for elderly stroke survivors include cognitively stimulating activities and participation in social groups. These interventions enhance cognitive function and support recovery by promoting neural repair. Additionally, EE helps to mitigate sensory deficits commonly observed in older adults, ultimately improving mental performance and quality of life. EE has shown promise in preventing relapse, enhancing attention, reducing anxiety, forestalling age-related DNA methylation alterations, and amplifying neurogenesis through heightened neural progenitor cell (NPC) populations. Aligning preclinical studies with clinical trials can enhance neurorehabilitation conditions for stroke patients, thereby optimizing the environments in which they recover. This can be achieved through the concerted efforts of multidisciplinary teams working collaboratively. This review explores how EE specifically impacts the aging brain and ischemic stroke, a major age-related neurological disorder with global health implications. The potential of enviro-mimetics and relevant clinical studies on EE's effects on ischemic stroke survivors are discussed. This review enhances our understanding of the effects of EE on aging and ischemic stroke, motivating further research aimed at refining strategies for stroke management and recovery.

A Scoping Review of Preclinical Environmental Enrichment Protocols in Models of Poststroke to Set the Foundations for Translating the Paradigm to Clinical Settings

The translation of the highly effective Environmental Enrichment (EE) paradigm from preclinical animal models to human clinical settings has been slow and showed inconsistent results. The primary translational challenge lies in defining what constitutes an EE for humans. To tackle this challenge, this study conducted a scoping review of preclinical EE protocols to explore what constitutes EE for animal models of stroke, laying the foundation for the translation of EE to human application. A systematic search was conducted in the MEDLINE, PsycINFO, and Web of Science databases to identify studies that conducted an EE intervention in the post-stroke animal model. A total of 116 studies were included in the review. A critical reflection of the characteristics of the included studies revealed that EE for post-stroke is a strategy that frequently modifies the animals' daily environment to create a richness of spatial, structural, and/or social opportunities to engage in a variety of daily life-related motor, cognitive, and social exploratory activities. These activities are relevant to the inhabiting individual and involve the activation of the body function(s) affected by the stroke. This review also identified six principles that underpinned the EE protocols: complexity (spatial and social), variety, novelty, targeting needs, scaffolding, and integration of rehabilitation tasks. These findings can be used as steppingstones to define what constitutes EE in human clinical applications and to develop a set of principles that can inform the design of EE protocols for patients after a stroke.

Transcranial near-infrared light promotes remyelination through AKT1/mTOR pathway to ameliorate postoperative neurocognitive disorder in aged mice

Postoperative neurocognitive disorder (PND) is a prevalent complication following surgery and anesthesia, characterized by progressive cognitive decline. The precise etiology of PND remains unknown, and effective targeted therapeutic strategies are lacking. Transcranial near-infrared light (tNIRL) has shown potential benefits for cognitive dysfunction diseases, but its effect on PND remains unclear. Our previous research indicated a close association between demyelination and PND. In other central nervous system (CNS) disorders, tNIRL has been demonstrated to facilitate remyelination in response to demyelination. In this study, we established the PND model in 18-month-old male C57BL/6 mice using isoflurane anesthesia combined with left common carotid artery exposure. Following surgery, PND-aged mice were subjected to daily 2.5-minute tNIRL treatment at 810 nm for three consecutive days. Subsequently, we observed that tNIRL significantly improved cognitive performance and reduced inflammatory cytokine levels in the hippocampus of PND mice. Furthermore, tNIRL increased the expression of oligodendrocyte transcription factor 2 (OLIG2) and myelin basic protein (MBP), promoting remyelination while enhancing synaptic function-associated proteins such as synaptophysin (SYP) and postsynaptic density protein 95 (PSD95). Further investigation revealed that tNIRL may activate the AKT1/mTOR pathway to facilitate remyelination in PND mice. These findings indicate that tNIRL is a novel non-invasive therapeutic approach for treating PND.

Enriched environment enhances angiogenesis in ischemic stroke through SDF-1/CXCR4/AKT/mTOR pathway

Environmental-gene interactions significantly influence various bodily functions. Enriched environment (EE), a non-pharmacological treatment method, enhances angiogenesis in ischemic stroke (IS). However, underlying the role of EE in angiogenesis in aged mice post-IS remain unclear. This study aimed to determine the potential mechanism by which EE mediates angiogenesis in 12-month-old IS mice and oxygen-glucose deprivation/reperfusion (OGD/R)-induced bEnd.3 cells. In vivo, EE treatment alleviated the neurological deficits, enhanced angiogenesis, upregulated SDF-1, VEGFA, and the AKT/mTOR pathway. In addition, exogenous SDF-1 treatment had a protective effect similar to that of EE treatment in aged mice with IS. However, SDF-1 neutralizing antibody, AMD3100 (CXCR4 inhibitor), ARQ092 (AKT inhibitor), and rapamycin (mTOR inhibitor) treatment blocked the neuroprotective effect of EE treatment and inhibited angiogenesis in IS mice. In vitro, exogenous SDF-1 promoted migration of OGD/R-induced bEnd.3 cells and activated the AKT/mTOR pathway. AMD3100, ARQ092, and rapamycin inhibited SDF-1-induced cell migration. Collectively, these findings demonstrate that EE enhances angiogenesis and improves the IS outcomes through SDF-1/CXCR4/AKT/mTOR pathway.

Enriched environment treatment promotes neurofunctional recovery by regulating the ALK5/Smad2/3/Gadd45β signaling pathway in rats with cerebral ischemia /reperfusion injury

It has been demonstrated that an enriched environment (EE) treatment can alter neuroplasticity in neurodegenerative diseases. However, the role of EE treatment in ischemic stroke remains unclear. Previous findings have revealed that EE treatment can promote cerebral activin-receptor-like-kinase-5 (ALK5) expression after cerebral ischemia/reperfusion (I/R) injury. ALK5 has been identified as a potential mediator of neuroplasticity through its modulation of Smad2/3 and Gadd45β. Therefore, the aim of this study was to investigate whether EE treatment could promote neurofunctional recovery by regulating the ALK5/Smad2/3/Gadd45β pathway. The study utilized the rat model of middle cerebral artery occlusion/reperfusion (MCAO/R). The ALK5/Smad2/3/Gadd45β signaling pathway changes were evaluated using western blotting (WB). Brain injury was assessed by infarct volume and neurobehavioral scores. The effect of EE treatment on neurogenesis was evaluated using Doublecortin (DCX) and Nestin, axonal plasticity with biotinylated dextran amine (BDA) nerve tracing, and dendritic plasticity was assessed using Golgi-Cox staining. EE treatment has been demonstrated to modulate the Smad2/3/Gadd45β pathway by regulating the expression of ALK5. The protective effects of EE treatment on brain infarct volume, neurological function, newborn neurons, dendritic and axonal plasticity following cerebral I/R injury were counteracted by ALK5 silencing. EE treatment can enhance neurofunctional recovery after cerebral I/R injury, which is achieved by regulating the ALK5/Smad2/3/Gadd45β signaling pathway to promote neuroplasticity.

Impact of early refined nursing program on prognosis of middle-aged and elderly patients with cognitive dysfunction combined with cerebral infarction

BACKGROUND

Cerebral infarction is a local or extensive necrosis of brain tissue. Subsequently, the corresponding neurological deficits appear. The incidence of cerebrovascular diseases in China is increasing gradually. After the onset of cerebrovascular disease, the most common sequelae include movement disorders, language disorders, and cognitive dysfunction.

AIM

To investigate the effect of early refined nursing program on the prognosis of middle-aged and elderly patients with cerebral infarction combined with cognitive dysfunction.

METHODS

A retrospective study was conducted to divide 60 patients with cerebral infarction and cognitive impairment into an experimental group (n = 32) and a control group (n = 28). The experimental group received early intensive care every day, and the control group received daily routine care. The scores of the Mini-Mental State Examination (MMSE) and the Trail Making Test (TMT), as well as the latency and amplitude of the event-related potential P300, were used as main indicators to evaluate changes in cognitive function, and changes in BDNF, TGF-β, and GDNF expression were used as secondary indicators.

RESULTS

Both groups experienced notable enhancements in MMSE scores, with the experimental group demonstrating higher scores than the control group (experimental: 28.75 ± 2.31; control: 25.84 ± 2.87). Moreover, reductions in TMT-A and TMT-B scores were observed in both groups (experimental: TMT-A 52.36 ± 6.18, TMT-B 98.47 ± 10.23; control: TMT-A 61.48 ± 7.92, TMT-B 112.63 ± 12.55), with the experimental group displaying lower scores. P300 Latency decreased (experimental: 270.63 ms ± 14.28 ms; control: 285.72 ms ± 16.45 ms), while amplitude increased (experimental: 7.82 μV ± 1.05 μV; control: 6.35 μV ± 0.98 μV) significantly in both groups, with superior outcomes in the experimental cohort. Additionally, the levels of the growth factors BDNF, TGF-β1, and GDNF surged (experimental: BDNF 48.37 ng/mL ± 5.62 ng/mL, TGF-β1 52.14 pg/mL ± 4.28 pg/mL, GDNF 34.76 ng/mL ± 3.89 ng/mL; control: BDNF 42.58 ng/mL ± 4.73 ng/mL, TGF-β1 46.23 pg/mL ± 3.94 pg/mL, GDNF 30.25 ng/mL ± 2.98 ng/mL) in both groups, with higher levels in the experimental group.

CONCLUSION

For middle-aged and elderly patients with cerebral infarction and cognitive dysfunction, early refined nursing can significantly improve their cognitive function and prognosis.

Impaired Meningeal Lymphatics and Glymphatic Pathway in Patients with White Matter Hyperintensity

White matter hyperintensity (WMH) represents a critical global medical concern linked to cognitive decline and dementia, yet its underlying mechanisms remain poorly understood. Here, humans are directly demonstrated that high WMH burden correlates with delayed drainage of meningeal lymphatic vessels (mLVs) and glymphatic pathway. Additionally, a longitudinal cohort study reveals that glymphatic dysfunction predicts WMH progression. Next, in a rat model of WMH, the presence of impaired lymphangiogenesis and glymphatic drainage is confirmed, followed by elevated microglial activation and white matter demyelination. Notably, enhancing meningeal lymphangiogenesis through adeno-associated virus delivery of vascular endothelial growth factor-C (VEGF-C) mitigates microglial gliosis and white matter demyelination. Conversely, blocking the growth of mLVs with a VEGF-C trap strategy exacerbates these changes. The findings highlight the role of mLVs and glymphatic pathway dysfunction in aggravating brain white matter injury, providing a potential novel strategy for WMH prevention and treatment.

Targeting pyroptosis to treat ischemic stroke: From molecular pathways to treatment strategy

Ischemic stroke is the primary reason for human disability and death, but the available treatment options are limited. Hence, it is imperative to explore novel and efficient therapies. In recent years, pyroptosis (a pro-inflammatory cell death characterized by inflammation) has emerged as an important pathological mechanism in ischemic stroke that can cause cell death through plasma membrane rupture and release of inflammatory cytokines. Pyroptosis is closely associated with inflammation, which exacerbates the inflammatory response in ischemic stroke. The level of inflammasomes, GSDMD, Caspases, and inflammatory factors is increased after ischemic stroke, exacerbating brain injury by mediating pyroptosis. Hence, inhibition of pyroptosis can be a therapeutic strategy for ischemic stroke. In this review, we have summarized the relationship between pyroptosis and ischemic stroke, as well as a series of treatments to attenuate pyroptosis, intending to provide insights for new therapeutic targets on ischemic stroke.

Enriched environment treatment promotes neural functional recovery together with microglia polarization and remyelination after cerebral ischemia in rats

BACKGROUND

Microglia activation and oligodendrocyte maturation are critical for remyelination after cerebral ischemia. Studies have shown that enriched environment (EE) can effectively alleviate stroke-induced neurological deficits. However, little is known about the mechanism associated with glial cells underlying the neuroprotection of EE. Therefore, this study focuses on investigating the effect of EE on activated microglia polarization as well as oligodendrogenesis in the progress of remyelination following cerebral ischemia.

METHODS

The ischemia/reperfusion (I/R) injury model was established by middle cerebral artery occlusion (MCAO) in rats. Animals executed 4 weeks of environmental intervention after performing MCAO or sham surgery and were divided into sham, MCAO, and MCAO+EE groups. Cognitive function, myelin damage, microglia activation and polarization, inflammation, oligodendrogenesis, remyelination, and protein expression of the PI3K/AKT/GSK3β signaling pathway were determined.

RESULTS

The staining of NeuN indicated that the infarct size of MCAO rats was decreased under EE. EE intervention improved animal performance in the Morris water maze test and novel object recognition test, promoting the recovery of cognitive function after I/R injury. EE treatment alleviated myelin damage in MCAO rats, as evidenced by the lower fluorescence intensity ratio of SMI-32/MBP in MCAO+EE group. EE increased the fluorescence intensity ratio of NG2+/Ki67+/Olig2+, MBP, and MOG, enhancing the proliferation and differentiation of OPCs and oligodendrogenesis after MCAO. In terms of remyelination, more myelinated axons and lower G/ratio were detected in MCAO+EE rats compared with MCAO group. Moreover, EE treatment decreased the number of Iba1+/CD86+ M1 microglia, increased the number of Iba1+/CD206+ M2 microglia, and suppressed the inflammation response after I/R injury, which could be attributed to the augmented expression of PI3K/AKT/GSK3β axis.

CONCLUSION

EE improved long‑term recovery of cognitive function after cerebral I/R injury, at least in part by promoting M2 microglia transformation through activation of the PI3K/AKT/GSK3β signaling pathway, inhibiting inflammation to provide a favorable microenvironment for oligodendrocyte maturation and remyelination. The effect of the EE on myelin and inflammation could account for the neuroprotection provided by EE.

Enriched environment enhanced the astrocyte-derived BDNF and VEGF expression and alleviate white matter injuries of rats with ischemic stroke

OBJECTIVES

Numerous studies have shown that an enriched environment can promote ischemic stroke and improve cognitive function. In addition, white matter is closely related to cognitive function. The effects and mechanisms of the enriched environment on white matter recovery after stroke have not been elucidated. This study will analyse the effects of the enriched environment on white matter and cognitive function in the post-stroke brain from the perspective of astrocytes and their secretions.

METHODS

Stroke models were used for middle cerebral artery occlusion model. post-operative rats were divided into sham-operated, standard and enriched environment groups. The degree of cerebral infarction was assessed by TTC staining and the degree of white matter damage was assessed by Luxol-Fast Blue staining. The prognosis after stroke was assessed using the longa score and Morris water maze test. Western Blot and immunofluorescence were used to quantify and localize astrocytes and their associated secretory factors and myelin protein markers.

RESULTS

We found that ischemic stroke can cause severe demyelination. After EE treatment, there was a significant increase in cerebral remyelination and a significant improvement in neurological and cognitive functions. Astrocyte, BDNF, and VEGF expression were significantly higher than in rats in the standard circumstances of stroke model.

CONCLUSION

These data suggest that the enriched environment contributes to brain white matter recovery and improvement of cognitive function after stroke. The mechanism is related to astrocytes and their secretions. EE can activate astrocytes to secrete BDNF and VEGF, which may be crucial to promote white matter recovery.

Dapagliflozin improves diabetic cognitive impairment via indirectly modulating the mitochondria homeostasis of hippocampus in diabetic mice

Cognitive impairment is increasingly recognized as an important comorbidity of diabetes progression; however, the underlying molecular mechanism is unclear. Dapagliflozin, an inhibitor of sodium-glucose co-transporter 2 (SGLT2), has shown promising effects against diabetes in rodent experiments and human clinical assays. This study aimed to determine the underlying mechanism and examine the effect of dapagliflozin on diabetic cognitive impairment. To create an in vivo model of diabetic cognitive impairment, streptozotocin (STZ)-induced diabetic mice were used. Dapagliflozin was administered to mice for 8 weeks. The context fear condition and Morris water maze test was used to evaluate mice's behavioral change. Western blotting was used to evaluate protein expression. Hematoxylin and eosin (HE) and Nissl staining were applied to monitor morphological and structural changes. Congo red staining was performed to identify the formation of senile plaques. Mitochondria morphology was examined using a transmission electron microscope, and blood flow in the mouse cerebral cortex was measured using a laser Doppler imaging assay. Comparison to the diabetes mellitus (DM) group, the dapagliflozin group had lower glucose levels. Behavioral studies have shown that dapagliflozin can restore memory deficits in diabetic mice. The murky cell membrane edges and Nissl bodies more difficult to identify in the DM group were revealed by HE and Nissl staining, which were both improved by dapagliflozin treatment. Dapagliflozin inhibited the progression of Aβ generation and the reduced cerebral blood flow in the DM group was rescued. After dapagliflozin treatment, damaged mitochondria and lack of SGLT2 in the hippocampus and cortex of diabetic mice were repaired. Diabetes-induced cognitive dysfunction was attenuated by dapagliflozin and the effect was indirect rather than direct.

Environmental Enrichment for Stroke and Traumatic Brain Injury: Mechanisms and Translational Implications

Acquired brain injuries, such as ischemic stroke, intracerebral hemorrhage (ICH), and traumatic brain injury (TBI), can cause severe neurologic damage and even death. Unfortunately, currently, there are no effective and safe treatments to reduce the high disability and mortality rates associated with these brain injuries. However, environmental enrichment (EE) is an emerging approach to treating and rehabilitating acquired brain injuries by promoting motor, sensory, and social stimulation. Multiple preclinical studies have shown that EE benefits functional recovery, including improved motor and cognitive function and psychological benefits mediated by complex protective signaling pathways. This article provides an overview of the enriched environment protocols used in animal models of ischemic stroke, ICH, and TBI, as well as relevant clinical studies, with a particular focus on ischemic stroke. Additionally, we explored studies of animals with stroke and TBI exposed to EE alone or in combination with multiple drugs and other rehabilitation modalities. Finally, we discuss the potential clinical applications of EE in future brain rehabilitation therapy and the molecular and cellular changes caused by EE in rodents with stroke or TBI. This article aims to advance preclinical and clinical research on EE rehabilitation therapy for acquired brain injury. © 2024 American Physiological Society. Compr Physiol 14:5291-5323, 2024.

Walnut-Derived Peptide Improves Cognitive Impairment in Colitis Mice Induced by Dextran Sodium Sulfate via the Microbiota-Gut-Brain Axis (MGBA)

In this study, we investigated the protective mechanism of walnut-derived peptide LPLLR (LP-5) against cognitive impairment induced in a dextran sodium sulfate (DSS)-induced colitis mouse model, with emphasis on the microbiota-gut-brain axis (MGBA). The results revealed that LP-5 could improve the learning ability and memory of mice with cognitive impairment and mitigate colitis symptoms, including weight loss, bloody stools, colon shortening, and histopathological changes. Additionally, LP-5 protected the integrity of the intestinal barrier by promoting the expression of tight junction proteins (TJs) while attenuating colonic inflammation by suppressing proinflammatory cytokine and epithelial cell apoptosis. Western blotting indicated that LP-5 treatment suppressed the inflammatory NF-κB/MLCK/MLC signaling pathway activity. Furthermore, LP-5 ameliorated hippocampal neuron damage and protected blood-brain barrier (BBB) integrity by downregulating microglia marker protein Iba-1, increasing TJ protein expression, and restoring the deterioration of synaptic proteins. Importantly, 16S rRNA sequencing results indicated that LP-5 reshaped the abundance of a wide range of gut microbiota at the phylum and genus levels, with increased Prevotella and Akkermansia associated with tryptophan (TRP), 5-hydroxytryptamine (5-HT), and 5-hydroxyindoleacetic acid (5-HIAA). These findings suggest that LP-5 could maintain intestinal barrier and BBB integrity, reverse gut dysbiosis, and improve learning and memory ability in colitis mice, providing novel insights into alterations of gut microbes in colitis and a potential new mechanism by which it causes cognitive impairment.

Enriched environment attenuates ferroptosis after cerebral ischemia/reperfusion injury by regulating iron metabolism

Preventing neuronal death after ischemic stroke (IS) is crucial for neuroprotective treatment, yet current management options are limited. Enriched environment (EE) is an effective intervention strategy that promotes the recovery of neurological function after cerebral ischemia/reperfusion (I/R) injury. Ferroptosis has been identified as one of the mechanisms of neuronal death during IS, and inhibiting ferroptosis can reduce cerebral I/R injury. Our previous research has demonstrated that EE reduced ferroptosis by inhibiting lipid peroxidation, but the underlying mechanism still needs to be investigated. This study aims to explore the potential molecular mechanisms by which EE modulates iron metabolism to reduce ferroptosis. The experimental animals were randomly divided into four groups based on the housing environment and the procedure the animals received: the sham-operated + standard environment (SSE) group, the sham-operated + enriched environment (SEE) group, the ischemia/reperfusion + standard environment (ISE) group, and the ischemia/reperfusion + enriched environment (IEE) group. The results showed that EE reduced IL-6 expression during cerebral I/R injury, hence reducing JAK2-STAT3 pathway activation and hepcidin expression. Reduced hepcidin expression led to decreased DMT1 expression and increased FPN1 expression in neurons, resulting in lower neuronal iron levels and alleviated ferroptosis. In addition, EE also reduced the expression of TfR1 in neurons. Our research suggested that EE played a neuroprotective role by modulating iron metabolism and reducing neuronal ferroptosis after cerebral I/R injury, which might be achieved by inhibiting inflammatory response and down-regulating hepcidin expression.

Environmental enrichment enhanced neurogenesis and behavioral recovery after stroke in aged rats

BACKGROUND AND PURPOSE

Age is identified as a significant prognostic factor for poorer outcome after stroke. However, environmental enrichment (EE) has been reported to promote functional recovery after ischemic stroke. The purpose of this study was to investigate whether environmental enrichment was beneficial to ischemic stroke in aged rats.

METHODS

Aged rats were randomly assigned as control rats, rats subjected to cerebral ischemia, and rats with cerebral ischemia treated with EE for 30 days. Focal cortical ischemia was induced by intracranial injection of endothelin-1 (ET-1). EE housing began one day after focal ischemia and was maintained for the whole experimental period. We used immunofluorescence staining to analyze the neurogenesis in the subventricular zone (SVZ) and TdT-mediated dUTP-biotin nick-end labeling (TUNEL) assay to evaluate apoptosis. The expression of neuronal nuclei, glial fibrillary acidic protein (GFAP) and Iba-1 around the infarcted area were also measured by double immunohistochemistry.

RESULTS

EE enhanced the proliferation of newborn neurons in the SVZ, as well as increased the long-term survival of newborn neurons. EE also exerted effects on inflammation after stroke. Furthermore, EE suppressed apoptosis and improved the motor functions after stroke in the aged rats.

CONCLUSIONS

EE improved post-stroke recovery on the basis of enhancing neurogenesis in aged rats.

Environmental modifications to rehabilitate social behavior deficits after acquired brain injury: What is the evidence?

Social behavior deficits are a common, debilitating consequence of traumatic brain injury and stroke, particularly when sustained during childhood. Numerous factors influence the manifestation of social problems after acquired brain injuries, raising the question of whether environmental manipulations can minimize or prevent such deficits. Here, we examine both clinical and preclinical evidence addressing this question, with a particular focus on environmental enrichment paradigms and differing housing conditions. We aimed to understand whether environmental manipulations can ameliorate injury-induced social behavior deficits. In summary, promising data from experimental models supports a beneficial role of environmental enrichment on social behavior. However, limited studies have considered social outcomes in the chronic setting, and few studies have addressed the social context specifically as an important component of the post-injury environment. Clinically, limited high-caliber evidence supports the use of specific interventions for social deficits after acquired brain injuries. An improved understanding of how the post-injury environment interacts with the injured brain, particularly during development, is needed to validate the implementation of rehabilitative interventions that involve manipulating an individuals' environment.

Multisensory Stimulation Reverses Memory Impairment in Adrβ3KO Male Mice

Norepinephrine plays an important role in modulating memory through its beta-adrenergic receptors (Adrβ: β₁, β₂ and β₃). Here, we hypothesized that multisensory stimulation would reverse memory impairment caused by the inactivation of Adrβ₃ (Adrβ₃KO) with consequent inhibition of sustained glial-mediated inflammation. To test this, 21- and 86-day-old Adrβ₃KO mice were exposed to an 8-week multisensory stimulation (MS) protocol that comprised gustatory and olfactory stimuli of positive and negative valence; intellectual challenges to reach food; the use of hidden objects; and the presentation of food in ways that prompted foraging, which was followed by analysis of GFAP, Iba-1 and EAAT2 protein expression in the hippocampus (HC) and amygdala (AMY). The MS protocol reduced GFAP and Iba-1 expression in the HC of young mice but not in older mice. While this protocol restored memory impairment when applied to Adrβ₃KO animals immediately after weaning, it had no effect when applied to adult animals. In fact, we observed that aging worsened the memory of Adrβ₃KO mice. In the AMY of Adrβ3KO older mice, we observed an increase in GFAP and EAAT2 expression when compared to wild-type (WT) mice that MS was unable to reduce. These results suggest that a richer and more diverse environment helps to correct memory impairment when applied immediately after weaning in Adrβ₃KO animals and indicates that the control of neuroinflammation mediates this response.

Pre exposure to enriched environment alleviates brain injury after ischemia-reperfusion by inhibiting p38MAPK/STAT1 pathway

BACKGROUND

Stroke is one of the major diseases that endangers human health. It is widely reported that enriched environment (EE) can improve the neurological function in different brain injury models. Recently, relevant researches have indicated that MAPK pathway is closely related to the inflammatory response in nervous system related diseases. However, whether pre exposure to EE (EE pretreatment) has a preventive effect, and its mechanism are not clear. Therefore, this study aimed to determine the possible benefits and related mechanisms of EE in preventing brain injury after acute ischemia-reperfusion.

METHODS

Adult Sprague Dawley rats were kept in enriched or standardized environments for 21 days. Then the middle cerebral artery of rats was occluded for one hour and 30 min, and then reperfusion was performed. Then their neurological deficit score was evaluated. Cerebral edema, along with ELISA and protein quantities of p38MAPK, JNK, ERK, IL-1β, TNF-α, and co-localization of Iba1 were assessed. Changes in neuroinflammation and apoptosis were also detected in the penumbra cortex.

RESULTS

Our research showed that EE pretreatment significantly alleviated acute cerebral ischemia-reperfusion injury in rats. Including the reduction of brain edema and apoptosis, and the improvement of neurological scores. In addition, the protein level of p38MAPK was significantly down regulated in EE pretreatment group, and the downstream protein STAT1 had the same trend. In addition, immunofluorescence results showed that Iba1 in EE pretreatment group decreased, the ELISA results showed that the classical proinflammatory cytokines increased significantly, while anti-inflammatory cytokines in EE pretreatment group increased, and the same results were obtained by Western blot analysis.

CONCLUSION

On the whole, our research demonstrated that EE pretreatment can have a protective effect on the organism by inhibiting the p38 MAPK/STAT1 pathway. Thus, EE can be one of the most promising means of disease prevention. Secondly, p38MAPK/STAT1 pathway may be a latent target for the prevention of acute ischemic stroke.

Pre-ischaemic Treatment with Enriched Environment Alleviates Acute Neuronal Injury by Inhibiting Endoplasmic Reticulum Stress-dependent Autophagy and Apoptosis

Enriched environment (EE) is effective in preventing cerebral ischemia-reperfusion (I/R) injury. However, little is known about the mechanism underlying the neuroprotection of EE preprocessing. Endoplasmic reticulum (ER) stress has been demonstrated to be extensively involved in I/R injury. We aimed to investigate the potential regulatory mechanism of ER stress in the neuroprotection of pre-ischemic EE. Rats were subjected to middle cerebral artery occlusion (MCAO) or sham surgery after 4 weeks of exposure in standard or enriched environments. We found that EE pretreatment alleviates acute neuronal injury after MCAO, as shown by reduced infarct volume and neurological deficit score. The expression of ER stress-related proteins, markers of autophagy, and apoptosis were detected to investigate the underlying mechanism. Our results showed that pre-ischemic EE inhibited the ER stress, as evidenced by the inactivation of activating transcription factor 6 (ATF6), protein kinase RNA (PKR)-like ER kinase (PERK), and inositol-requiring enzyme 1 (IRE1) pathways. Moreover, the rats reared in EE were detected with lower autophagic activity and apoptosis levels. The decrease in activating transcription factor 4 (ATF4), C/EBP homologous protein (CHOP), and phospho-c-Jun N-terminal kinases (p-JNK) expression suggested EE pretreatment might inhibit autophagy and apoptosis via modulating ER stress-mediated PERK-ATF4-CHOP and IRE1-JNK signal pathways, which provides a new idea for the prevention of the deleterious cerebral and functional consequences of ischemic stroke.

Dialogue among Lymphocytes and Microglia in Glioblastoma Microenvironment

Simple Summary

In this review, we summarize in vitro and in vivo studies related to glioblastoma models and human patients to outline the symbiotic bidirectional interaction between microglia, lymphocytes, and tumor cells that develops during tumor progression. Particularly, we highlight the current experimental therapeutic approaches that aim to shape these interplays, such as adeno-associated virus (AAV) delivery and CAR-T and -NK cell infusion, and to modulate the tumor microenvironment in an anti-tumoral way, thus counteracting glioblastoma growth.

Abstract

Microglia and lymphocytes are fundamental constituents of the glioblastoma microenvironment. In this review, we summarize the current state-of-the-art knowledge of the microglial role played in promoting the development and aggressive hallmarks of this deadly brain tumor. Particularly, we report in vitro and in vivo studies related to glioblastoma models and human patients to outline the symbiotic bidirectional interaction between microglia, lymphocytes, and tumor cells that develops during tumor progression. Furthermore, we highlight the current experimental therapeutic approaches that aim to shape these interplays, such as adeno-associated virus (AAV) delivery and CAR-T and -NK cell infusion, and to modulate the tumor microenvironment in an anti-tumoral way, thus counteracting glioblastoma growth.