Postischemic Housing Environment on Cerebral Metabolism and Neuron Apoptosis after Focal Cerebral Ischemia in Rats

Environmental Enrichment in Stroke Research: an Update

Environmental enrichment (EE) refers to different forms of stimulation, where the environment is designed to improve the levels of sensory, cognitive, and motor stimuli, inducing stroke recovery in animal models. Stroke is a leading cause of mortality and neurological disability among older adults, hence the importance of developing strategies to improve recovery for such patients. This review provides an update on recent findings, compiling information regarding the parameters affected by EE exposure in both preclinical and clinical studies. During stroke recovery, EE exposure has been shown to improve both the cognitive and locomotor aspects, inducing important neuroplastic alterations, increased angiogenesis and neurogenesis, and modified gene expression, among other effects. There is a need for further research in this field, particularly in those aspects where the evidence is inconclusive. Moreover, it is necessary refine and adapt the EE paradigms for application in human patients.

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.

Intracerebral hirudin injection alleviates cognitive impairment and oxidative stress and promotes hippocampal neurogenesis in rats subjected to cerebral ischemia

Cerebral ischemia starts with cerebral blood flow interruption that causes severely limited oxygen and glucose supply, eliciting a cascade of pathological events, such as excitotoxicity, oxidative stress, calcium dysregulation, and inflammatory response, which could ultimately result in neuronal death. Hirudin has beneficial effects in ischemic stroke and possesses antioxidant and anti-inflammatory properties. Therefore, we investigated the biological functions of hirudin and its related mechanisms in cerebral ischemia. The ischemia-like conditions were induced by transient middle cerebral artery occlusion (MCAO). To investigate hirudin roles, intracerebroventricular injection of 10 U hirudin was given to the rats. Cognitive and motor functions were examined by beam walking and Morris water maze tests. 2,3,5-triphenyl tetrazolium chloride-stained brain sections were used to measure infarct volume. Oxidative stress was determined by assessment of oxidative stress markers. The proliferated cells were labeled by BrdU and Nestin double staining. Western blotting was performed to measure protein levels. Hirudin administration improved cognitive and motor deficits post-ischemia. Hirudin reduced brain infarction and neurological damage in MCAO-subjected rats. Hirudin alleviated oxidative stress and enhanced neurogenesis in ischemic rats. Hirudin facilitated the promotion of phosphorylation of extracellular signal-regulated kinase (ERK) 1/2 and serine-threonine kinase. In sum, hirudin alleviates cognitive deficits by attenuating oxidative stress and promoting hippocampal neurogenesis through the regulation of ERK1/2 and serine-threonine kinase in MCAO-subjected rats.

After Ischemic Stroke, Minocycline Promotes a Protective Response in Neurons via the RNA-Binding Protein HuR, with a Positive Impact on Motor Performance

Ischemic stroke is the most common cause of adult disability and one of the leading causes of death worldwide, with a serious socio-economic impact. In the present work, we used a new thromboembolic model, recently developed in our lab, to induce focal cerebral ischemic (FCI) stroke in rats without reperfusion. We analyzed selected proteins implicated in the inflammatory response (such as the RNA-binding protein HuR, TNFα, and HSP70) via immunohistochemistry and western blotting techniques. The main goal of the study was to evaluate the beneficial effects of a single administration of minocycline at a low dose (1 mg/kg intravenously administered 10 min after FCI) on the neurons localized in the penumbra area after an ischemic stroke. Furthermore, given the importance of understanding the crosstalk between molecular parameters and motor functions following FCI, motor tests were also performed, such as the Horizontal Runway Elevated test, CatWalk™ XT, and Grip Strength test. Our results indicate that a single administration of a low dose of minocycline increased the viability of neurons and reduced the neurodegeneration caused by ischemia, resulting in a significant reduction in the infarct volume. At the molecular level, minocycline resulted in a reduction in TNFα content coupled with an increase in the levels of both HSP70 and HuR proteins in the penumbra area. Considering that both HSP70 and TNF-α transcripts are targeted by HuR, the obtained results suggest that, following FCI, this RNA-binding protein promotes a protective response by shifting its binding towards HSP70 instead of TNF-α. Most importantly, motor tests showed that reduced inflammation in the brain damaged area after minocycline treatment directly translated into a better motor performance, which is a fundamental outcome when searching for new therapeutic options for clinical practice.

Enriched environment remodels the central immune environment and improves the prognosis of acute ischemic stroke in elderly mice with chronic ischemia

With the aging of many populations, cognitive and motor dysfunction caused by ischemic stroke (IS) secondary to long-term chronic cerebral ischemia presents a global problem. Enriched environment (EE), a classic paradigm of environment response and genetic interaction, has shown tremendous influence on the brain. This research aimed to investigate the potential effect of EE on cognitive and motor function in mice with chronic cerebral ischemia and secondary IS. In the chronic cerebral hypoperfusion (CCH) phase, EE treatment improved behavior performance by alleviating neuronal loss and white matter myelin damage, promoting the expression of brain-derived neurotrophic factor (BDNF) and phosphor-cAMP response element binding protein (p-CREB). Furthermore, infiltration of microglia/macrophages and astrocytes was inhibited, and the levels of IL-1β and TNFα were decreased. In the IS phase, EE altered the neuronal outcome on day 21 but not on day one after IS. In addition, EE inhibited IS-induced infiltration of microglia/macrophages and astrocytes, mediated the polarization of microglia/macrophages, and reduced pro-inflammatory factors. Importantly, EE improved IS-induced cognitive and motor deficits on day 21. Collectively, our work demonstrates that EE protects mice from cognitive and motor dysfunction and inhibits neuroinflammation caused by CCH and IS.

An Enriched Environment Promotes Motor Function through Neuroprotection after Cerebral Ischemia

Stroke seriously affects human health. Many studies have shown that enriched environment (EE) can promote functional recovery after stroke, but the intrinsic mechanisms remain unclear. In order to study the internal mechanisms of EE involved in functional recovery after ischemic stroke and which mechanism plays a leading role in the recovery of limb function after cerebral infarction, key proteins potentially involved in neuronal protection and synaptic remodeling in the ischemic penumbra have been investigated. In this study, adult C57BL/6 mice after permanent middle cerebral artery occlusion (pMCAO) were assigned to the EE and standard housing (SH) groups 3 days after operation. The EE house was spacious that contained a large variety of small toys; the SH was a normal sized cage. Sham-operated mice without artery occlusion were housed under standard conditions and were fed a normal diet. On days 3, 7, 14, and 21, postoperative motor functional recovery was tested using the modified neurological severity score (mNSS) and the Rotarod test. The expression of B-cell lymphoma-2 (Bcl-2), Bcl-2-associated X protein (Bax), growth-associated protein-43 (GAP-43), and synaptophysin (SYN) was examined by western blotting and immunofluorescence staining. The motor functional recovery (based on the mNSS and Rotarod test 3, 7, 14, and 21 days post operation) of mice in the EE group improved significantly compared to the SH group. The expression of GAP-43 and SYN and the ratio of Bcl-2/Bax were all upregulated in the EE group compared to the SH group. In addition, we also explored the relationship between neuronal protection and synaptic remodeling in the EE-mediated recovery of limb function after cerebral infarction by correlation analysis. Correlation analysis showed that compared with the increase of Bcl-2/Bax ratio, the increased expression of GAP-43 and SYN was more closely related to the recovery of limb function in ischemic mice. These data support the hypothesis that EE can promote the process of improvement of limb dysfunction induced by ischemic stroke, and this behavior restoration may, via promoting neuroprotection in the ischemic penumbra, be dependent on the regulation of the expression of GAP-43, SYN, Bcl-2, and Bax. A limitation of the study was that we only observed several representative key indicators of synaptic remodeling and neuronal apoptosis, without an in-depth study of the potential mechanisms involved.

Mesencephalic astrocyte-derived neurotrophic factor (MANF): Structure, functions and therapeutic potential

Mesencephalic astrocyte-derived neurotrophic factor (MANF) is a novel evolutionarily conserved protein present in both vertebrate and invertebrate species. MANF shows distinct structural and functional properties than the traditional neurotrophic factors (NTF). MANF is composed of an N-terminal saposin-like lipid-binding domain and a C-terminal SAF-A/B, Acinus and PIAS (SAP) domain connected by a short linker. The two well-described activities of MANF include (1) role as a neurotrophic factor that plays direct neuroprotective effects in the nervous system and (2) cell protective effects in the animal models of non-neuronal diseases, including retinal damage, diabetes mellitus, liver injury, myocardial infarction, nephrotic syndrome, etc. The main objective of the current review is to provide up-to-date insights regarding the structure of MANF, mechanisms regulating its expression and secretion, physiological functions in various tissues and organs, protective effects during aging, and potential clinical applications. Together, this review highlights the importance of MANF in reversing age-related dysfunction and geroprotection.

Enriched Environment-Induced Neuroprotection against Cerebral Ischemia-Reperfusion Injury Might Be Mediated via Enhancing Autophagy Flux and Mitophagy Flux

Background

Enriched environment (EE) can protect the brain against damages caused by an ischemic stroke; however, the underlying mechanism remains elusive. Autophagy and mitochondria quality control are instrumental in the pathogenesis of ischemic stroke. In this study, we investigated whether and how autophagy and mitochondria quality control contribute to the protective effect of EE in the acute phase of cerebral ischemia–reperfusion injury.

Methods

We exposed transient middle cerebral artery occlusion (tMCAO) mice to EE or standard condition (SC) for 7 days and then studied them for neurological deficits, autophagy and inflammation-related proteins, and mitochondrial morphology and function.

Results

Compared to tMCAO mice in the SC group, those in the EE group showed fewer neurological deficits, relatively downregulated inflammation, higher LC3 expression, higher mitochondrial Parkin levels, higher mitochondrial fission factor dynamin-related protein-1 (Drp1) levels, lower p62 expression, and lower autophagy inhibitor mTOR expression. Furthermore, we found that the EE group showed a higher number of mitophagosomes and normal mitochondria, fewer mitolysosomes, and relatively increased mitochondrial membrane potential.

Conclusion

These results suggested that EE enhances autophagy flux by inhibiting mTOR and enhances mitophagy flux via recruiting Drp1 and Parkin to eliminate dysfunctional mitochondria, which in turn inhibits inflammation and alleviates neurological deficits. Limitations. The specific mechanisms through which EE promotes autophagy and mitophagy and the signaling pathways that link them with inflammation need further study.

Anfibatide alleviates inflammation and apoptosis via inhibiting NF-kappaB/NLRP3 axis in ischemic stroke

Recent evidence suggests that Nod-like receptor protein-3 (NLRP3) inflammasome is a key mediator of inflammatory response and can induce the activation of apoptosis signaling pathways in ischemic stroke. In this research, we assessed the effects of anfibatide (ANF) on inflammatory and apoptosis in cerebral ischemic injury and the potential mechanisms. Middle cerebral artery occlusion (MCAO) model was established on male Sprague-Dawley rats to induce cerebral ischemia/reperfusion (I/R) injury in vivo. Primary cortical neurons (PCN) cells were exposed to oxygen-glucose deprivation and reintroduction (OGD/R) to mimic cerebral I/R injury in vitro. The results showed that ANF markedly alleviated infarct volume, neurological deficit and neurobehavioral impairment in MCAO/R rats, enhanced cell viability and decreased LDH release in PCN after OGD/R. The number of TUNEL-positive cells, Bax, cleaved-caspase-3, p-IκBα, p-p65, NLRP3, ASC, cleaved caspase-1, IL-β and IL-18 proteins expression were significantly upregulated in the cortex of MCAO/R rats and PCN exposed to OGD/R, NLRP3 and caspase-1 mRNA levels were also evidently elevated. Bcl-2 protein expression significantly decreased in the cortex of MCAO/R rats. Treatment with ANF obviously inhibited the expression of p-IκBα, p-p65, NLRP3, ASC, cleaved caspase-1, Bax and cleaved-caspase-3, promoted the expression of Bcl-2, then decreased the TUNEL-positive cell number and the level of inflammatory cytokines (IL-β and IL-18) in cerebral ischemia reperfusion in vito and in vitro. Our findings suggest that ANF exerts effects of alleviating inflammation and apoptosis through inhibiting NF-kappaB/NLRP3 axis. ANF is a potential candidate for treating cerebral I/R injury.

Voluntary running exercise after focal cerebral ischemia ameliorates dendritic spine loss and promotes functional recovery

Cerebral infarction causes motor, sensory, and cognitive impairments. Although rehabilitation enhances recovery of activities of daily living after cerebral infarction, its mechanism remains elusive due to the lack of reproducibility and low survival rate of brain ischemic model animals. Here, to investigate the relationship between rehabilitative intervention, motor function, and pathophysiological remodeling of the tissue in the ipsilateral hemisphere after cerebral infarction, we took advantage of a highly reproducible model of cerebral infarction using C.B-17/Icr-^+/+Jcl mice. In this model, we confirmed that voluntary running exercise improved functional recovery after ischemia. Exercise did not alter the volume of infarction or survived cortex, or the number of NeuN-labeled cells in the peri-infarct cortex. In mice who did not exercise, the number of basal dendritic spines of layer 5 pyramidal cells decreased in the peri-infarct motor cortex, whereas in mice who exercised it remained at the normal level. The voluntary exercise intervention maintained basal dendritic spine density within the peri-infarct area, which may reflect an adaptive remodeling of the surviving neural circuitry that might contribute to promoting the recovery of activities of daily living.

Transcranial Doppler Combined With Quantitative Electroencephalography Brain Function Monitoring for Estimating the Prognosis of Patients With Posterior Circulation Cerebral Infarction

Posterior circulation cerebral infarction (PCCI) can lead to deceased infratentorial cerebral blood flow (CBF) and metabolism. Neural activity is closely related to regional cerebral blood flow both spatially and temporally. Transcranial Doppler (TCD) combined with quantitative electroencephalography (QEEG) is a technique that evaluates neurovascular coupling and involves synergy between the metabolic and vascular systems. This study aimed to monitor brain function using TCD-QEEG and estimate the efficacy of TCD-QEEG for predicting the prognosis of patients with PCCI. We used a TCD-QEEG recording system to perform quantitative brain function monitoring; we recorded the related clinical variables simultaneously. The data were analyzed using a Cox proportional hazards regression model. Receiver-operating characteristic (ROC) curve analysis was used to evaluate the cut-off for the diastolic flow velocity (VD) and (delta + theta)/(alpha + beta) ratio (DTABR). The area under the ROC curve (AUROC) was calculated to assess the predictive validity of the study variables. Forty patients (aged 63.7 ± 9.9 years; 30 men) were assessed. Mortality at 90 days was 40%. The TCD indicators of VD [hazard ratio (HR) 0.168, confidence interval (CI) 0.047-0.597, p = 0.006] and QEEG indicators of DTABR (HR 12.527, CI 1.637-95.846, p = 0.015) were the independent predictors of the clinical outcomes. The AUROC after combination of VD and DTABR was 0.896 and showed better predictive accuracy than the Glasgow Coma Scale score (0.75), VD (0.76), and DTABR (0.781; all p < 0.05). TCD-QEEG provides a good understanding of the coupling mechanisms in the brain and can improve our ability to predict the prognosis of patients with PCCI.

Effectiveness and mechanisms of enriched environment in post-stroke cognitive impairment

Post-stroke cognitive impairment (PSCI) is one of the most common complications of stroke, it is also an important reason for the poor prognosis in stroke patients with motor and speech dysfunction. Enriched Environment (EE), a novel and easy-to-implement rehabilitation treatment strategy, is thought to be a potential intervention for PSCI recently. In this paper, we review the therapeutic effects and related mechanisms of EE in PSCI from the level of animal research and clinical application. Besides, we further discuss the application prospects and limitations of EE in PSCI patients.

Enriched environment boosts the post-stroke recovery of neurological function by promoting autophagy

Autophagy is crucial for maintaining cellular homeostasis, and can be activated after ischemic stroke. It also participates in nerve injury and repair. The purpose of this study was to investigate whether an enriched environment has neuroprotective effects through affecting autophagy. A Sprague-Dawley rat model of transient ischemic stroke was prepared by occlusion of the middle cerebral artery followed by reperfusion. One week after surgery, these rats were raised in either a standard environment or an enriched environment for 4 successive weeks. The enriched environment increased Beclin-1 expression and the LC3-II/LC3-I ratio in the autophagy/lysosomal pathway in the penumbra of middle cerebral artery-occluded rats. Enriched environment-induced elevations in autophagic activity were mainly observed in neurons. Enriched environment treatment also promoted the fusion of autophagosomes with lysosomes, enhanced the lysosomal activities of lysosomal-associated membrane protein 1, cathepsin B, and cathepsin D, and reduced the expression of ubiquitin and p62. After 4 weeks of enriched environment treatment, neurological deficits and neuronal death caused by middle cerebral artery occlusion/reperfusion were significantly alleviated, and infarct volume was significantly reduced. These findings suggest that neuronal autophagy is likely the neuroprotective mechanism by which an enriched environment promotes recovery from ischemic stroke. This study was approved by the Animal Ethics Committee of the Kunming University of Science and Technology, China (approval No. 5301002013855) on March 1, 2019.

Ablation of TMEM126B protects against oxygen-glucose deprivation/reoxygenation-induced injuries of PC12 cells via maintaining mitochondrial anti-apoptotic functions

Ischemia reperfusion (I/R) injury is a key contributing factor to the pathogenic mechanism involved in cerebral infarction. Transmembrane protein 126b (TMEM126B), a mitochondrial complex I assembly factor, has been reported to have an intimate association with disease progression, but is little known in ischemia stroke. The present study was designed to explore the effects of TEME126B on oxygen-glucose deprivation/reoxygenation (OGD/R)-induced neuronal PC12 cells. The mRNA level of TMEM126B was determined using qRT-PCR. The levels of ROS, MDA, and SOD, as well as inflammatory cytokines, were measured using corresponding commercial kits. Cell apoptosis rate was assayed by flow cytometry analysis, and the apoptosis-related proteins were measured using western blotting. ATP production measured by colorimetric reaction and mitochondrial membrane potential measured by JC-1 staining were conducted to determine mitochondrial dysfunction. The results showed that TMEM126B was upregulated upon I/R injury in vitro and in clinical, and was positively corrected with the degree of oxidative stress. TMEM126B knockdown significantly reduced oxidative stress and inflammation in OGD/R-induced PC12 cells. TMEM126B knockdown also attenuated cell apoptosis rate, accompanied with increased expressions of Bcl-2, XIAP and cleaved PARP-1, and decreased expressions of Bax, cleaved caspase 3 and cleaved caspase 9. Furthermore, TMEM126B knockdown exhibited cytoprotective roles through alleviating mitochondrial dysfunction, as assessed by ATP production and mitochondrial membrane potential. Collectively, this study indicates that TMEM126B knockdown protects against OGD/R-induced neuronal injuries through relieving oxidative stress, inflammation, apoptosis and mitochondria dysfunction, which provides a promising target for ischemic stroke treatment.

Enriched environment alleviates post-stroke cognitive impairment through enhancing α7-nAChR expression in rats

ABSTRACT Background: Enriched environment (EE) is a simple and effective intervention to improve cognitive function in post-stroke cognitive impairment (PSCI), partly due to the rebalancing of the cholinergic signaling pathway in the hippocampus. α7-nicotinic acetylcholine receptor (α7-nAChR) is a cholinergic receptor whose activation inhibits inflammation and promotes the recovery of neurological function in PSCI patients. However, it is still unclear whether EE can regulate α7-nAChR and activate the cholinergic anti-inflammatory pathway (CAP) in PSCI. Objective: To investigate the effects of EE on cognitive impairment, and the role of α7-nAChR in PSCI. Methods: A PSCI rat model was induced by middle cerebral artery occlusion and reperfusion (MCAO/R) and were reared in standard environment (SE) or EE for 28d, control group with sham surgery. Cognitive function was determined by Morris water maze test. The long-term potentiation (LTP) was assessed by Electrophysiology. Histopathological methods were used to determine infarct volume, α7-nAChR expression and the cytokines and cholinergic proteins expression. Results: Compared with SE group, rats in EE group had better cognitive function, higher expression of α7-nAChR positive neurons in hippocampal CA1 region. In addition, EE attenuated unfavorable changes induced by MCAO/R in cytokines and cholinergic proteins, and also enhanced LTP promoted by nicotine and attenuated by α-BGT; but showed no significantly difference in infarct volume. Conclusions: EE markedly improves cognitive impairment and enhances neuroplasticity in PSCI rats, which may be closely related to enhancement of α7-nAChR expression.

Environmental enrichment enhances post-ischemic cerebral blood flow and functional hyperemia in the ipsilesional somatosensory cortex

Environmental enrichment has been reported to promote functional recovery in an ischemic stroke. However, the underlying mechanism remains unclear. This study aimed to investigate the effect of environmental enrichment treatment on post-ischemic cerebral blood flow and functional hyperemia in the ipsilesional primary somatosensory cortex of rats. With laser speckle imaging, we were able to monitor the resting cerebral blood flow alteration in the middle cerebral artery occlusion model. Both 3- and 28-day post-ischemic infarct volumes were then examined with triphenyltetrazolium chloride and cresyl violet staining, respectively. We found that an exposure to environmental enrichment was associated with higher post-ischemic cerebral blood flow and less brain tissue loss in the ipsilesional primary somatosensory cortex compared with the standard cage environment. Furthermore, environmental enrichment also enhanced the cerebral blood flow response to whisker stimulation in the ipsilesional barrel cortex when measured 28 days after the middle cerebral artery occlusion. Together, the data suggested that an exposure to environmental enrichment promoted the restoration of cerebral blood flow in the ipsilesional cortex and contributed to a better coupling between functional activation and cerebral blood flow change, which might be the possible mechanisms underlying the neuroprotective effects of EE after ischemia.

Ligustilide protects PC12 cells from oxygen-glucose deprivation/reoxygenation-induced apoptosis via the LKB1-AMPK-mTOR signaling pathway

Autophagy has been shown to have a protective effect against brain damage. Ligustilide (LIG) is a bioactive substance isolated from Ligusticum chuanxiong, a traditional Chinese medicine. LIG has a neuroprotective effect; however, it is unclear whether this neuroprotective effect involves autophagy. In this study, PC12 cells were treated with 1 × 10^–5–1 × 10^–9 M LIG for 0, 3, 12 or 24 hours, and cell proliferation was evaluated using the 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS) assay. Treatment with 1 × 10^–6 M LIG for 3 hours had the greatest effect on cell proliferation, and was therefore used for subsequent experiments. PC12 cells were pre-treated with 1 × 10^–6 M LIG for 3 hours, cultured in 95% N₂/5% CO₂ in Dulbecco’s modified Eagle’s medium without glucose or serum for 4 hours, and then cultured normally for 16 hours, to simulate oxygen-glucose deprivation/reoxygenation (OGD/R). Cell proliferation was assessed with the MTS assay. Apoptosis was detected by flow cytometry. The expression levels of apoptosis-related proteins, Bcl-2 and Bax, autophagy-related proteins, Beclin 1 and microtubule-associated protein l light chain 3B (LC3-II), and liver kinase B1 (LKB1)-5′-adenosine monophosphate-activated protein kinase (AMPK)-mammalian target of rapamycin (mTOR) signaling pathway-related proteins were assessed by western blot assay. Immunofluorescence staining was used to detect LC3-II expression. Autophagosome formation was observed by electron microscopy. LIG significantly decreased apoptosis, increased Bcl-2, Beclin 1 and LC3-II expression, decreased Bax expression, increased LC3-II immunoreactivity and the number of autophagosomes, and activated the LKB1-AMPK-mTOR signaling pathway in PC12 cells exposed to OGD/R. The addition of the autophagy inhibitor 3-methyladenine or dorsomorphin before OGD/R attenuated the activation of the LKB1-AMPK-mTOR signaling pathway in cells treated with LIG. Taken together, our findings show that LIG promotes autophagy and protects PC12 cells from apoptosis induced by OGD/R via the LKB1-AMPK-mTOR signaling pathway.