IGF-1 alleviates NMDA-induced excitotoxicity in cultured hippocampal neurons against autophagy via the NR2B/PI3K-AKT-mTOR pathway

High salt diet induces cognitive impairment and is linked to the activation of IGF1R/mTOR/p70S6K signaling

A high-salt diet (HSD) has been associated with various health issues, including hypertension and cardiovascular diseases. However, recent studies have revealed a potential link between high salt intake and cognitive impairment. This study aims to investigate the effects of high salt intake on autophagy, tau protein hyperphosphorylation, and synaptic function and their potential associations with cognitive impairment. To explore these mechanisms, 8-month-old male C57BL/6 mice were fed either a normal diet (0.4% NaCl) or an HSD (8% NaCl) for 3 months, and Neuro-2a cells were incubated with normal medium or NaCl medium (80 mM). Behavioral tests revealed learning and memory deficits in mice fed the HSD. We further discovered that the HSD decreased autophagy, as indicated by diminished levels of the autophagy-associated proteins Beclin-1 and LC3, along with an elevated p62 protein level. HSD feeding significantly decreased insulin-like growth factor-1 receptor (IGF1R) expression in the brain of C57BL/6 mice and activated mechanistic target of rapamycin (mTOR) signaling. In addition, the HSD reduced synaptophysin and postsynaptic density protein 95 (PSD95) expression in the hippocampus and caused synaptic loss in mice. We also found amyloid β accumulation and hyperphosphorylation of tau protein at different loci both in vivo and in vitro. Overall, this study highlights the clinical significance of understanding the impact of an HSD on cognitive function. By targeting the IGF1R/mTOR/p70S6K pathway or promoting autophagy, it may be possible to mitigate the negative effects of high salt intake on cognitive function.

Interleukin-4 protects retinal ganglion cells and promotes axon regeneration

BACKGROUND

The preservation of retinal ganglion cells (RGCs) and the facilitation of axon regeneration are crucial considerations in the management of various vision-threatening disorders. Therefore, we investigate the efficacy of interleukin-4 (IL-4), a potential therapeutic agent, in promoting neuroprotection and axon regeneration of retinal ganglion cells (RGCs) as identified through whole transcriptome sequencing in an in vitro axon growth model.

METHODS

A low concentration of staurosporine (STS) was employed to induce in vitro axon growth. Whole transcriptome sequencing was utilized to identify key target factors involved in the molecular mechanism underlying axon growth. The efficacy of recombinant IL-4 protein on promoting RGC axon growth was validated through in vitro experiments. The protective effect of recombinant IL-4 protein on somas of RGCs was assessed using RBPMS-specific immunofluorescent staining in mouse models with optic nerve crush (ONC) and N-methyl-D-aspartic acid (NMDA) injury. The protective effect on RGC axons was evaluated by anterograde labeling of cholera toxin subunit B (CTB), while the promotion of RGC axon regeneration was assessed through both anterograde labeling of CTB and immunofluorescent staining for growth associated protein-43 (GAP43).

RESULTS

Whole-transcriptome sequencing of staurosporine-treated 661 W cells revealed a significant upregulation in intracellular IL-4 transcription levels during the process of axon regeneration. In vitro experiments demonstrated that recombinant IL-4 protein effectively stimulated axon outgrowth. Subsequent immunostaining with RBPMS revealed a significantly higher survival rate of RGCs in the rIL-4 group compared to the vehicle group in both NMDA and ONC injury models. Axonal tracing with CTB confirmed that recombinant IL-4 protein preserved long-distance projection of RGC axons, and there was a notably higher number of surviving axons in the rIL-4 group compared to the vehicle group following NMDA-induced injury. Moreover, intravitreal delivery of recombinant IL-4 protein substantially facilitated RGC axon regeneration after ONC injury.

CONCLUSION

The recombinant IL-4 protein exhibits the potential to enhance the survival rate of RGCs, protect RGC axons against NMDA-induced injury, and facilitate axon regeneration following ONC. This study provides an experimental foundation for further investigation and development of therapeutic agents aimed at protecting the optic nerve and promoting axon regeneration.

Interplay of G-proteins and Serotonin in the Neuroimmunoinflammatory Model of Chronic Stress and Depression: A Narrative Review

INTRODUCTION

This narrative review addresses the clinical challenges in stress-related disorders such as depression, focusing on the interplay between neuron-specific and pro-inflammatory mechanisms at the cellular, cerebral, and systemic levels.

OBJECTIVE

We aim to elucidate the molecular mechanisms linking chronic psychological stress with low-grade neuroinflammation in key brain regions, particularly focusing on the roles of G proteins and serotonin (5-HT) receptors.

METHODS

This comprehensive review of the literature employs systematic, narrative, and scoping review methodologies, combined with systemic approaches to general pathology. It synthesizes current research on shared signaling pathways involved in stress responses and neuroinflammation, including calcium-dependent mechanisms, mitogen-activated protein kinases, and key transcription factors like NF-κB and p53. The review also focuses on the role of G protein-coupled neurotransmitter receptors (GPCRs) in immune and pro-inflammatory responses, with a detailed analysis of how 13 of 14 types of human 5-HT receptors contribute to depression and neuroinflammation.

RESULTS

The review reveals a complex interaction between neurotransmitter signals and immunoinflammatory responses in stress-related pathologies. It highlights the role of GPCRs and canonical inflammatory mediators in influencing both pathological and physiological processes in nervous tissue.

CONCLUSION

The proposed Neuroimmunoinflammatory Stress Model (NIIS Model) suggests that proinflammatory signaling pathways, mediated by metabotropic and ionotropic neurotransmitter receptors, are crucial for maintaining neuronal homeostasis. Chronic mental stress can disrupt this balance, leading to increased pro-inflammatory states in the brain and contributing to neuropsychiatric and psychosomatic disorders, including depression. This model integrates traditional theories on depression pathogenesis, offering a comprehensive understanding of the multifaceted nature of the condition.

The NR2B-targeted intervention alleviates the neuronal injuries at the sub-acute stage of cerebral ischemia: an exploration of stage-dependent strategy against ischemic insults

Stroke is reported to be the second leading cause of death worldwide, among which ischemic stroke has fourfold greater incidence than intracerebral hemorrhage. Excitotoxicity induced by NMDAR plays a central role in ischemic stroke-induced neuronal death. However, intervention targeted NMDARs against ischemic stroke has failed, which may result from the complex composition of NMDARs and the dynamic changes of their subunits. In this current study, the levels of NR1, NR2A and NR2B subunits of NMDARs were observed upon different time points during the reperfusion after 1 h ischemia with the western blot assay. It was found that the changes of NR1 subunit were only detected after ischemia 1 h/reperfusion 1 day (1 d). While, the changes of NR2A and NR2B subunits may last to ischemia 1 h/reperfusion 7 day(7 d), indicating that NR2subunits may be a potential target for ischemia-reperfusion injuries at the sub-acute stage of ischemic stroke. Simultaneously, mitochondrial injuries in neurons were investigated with transmission electron microscopy (TEM), and mitochondrial dysfunction was evaluated with mitochondrial membrane proteins oxidative respiratory chain complex and OCR. When the antagonist of NMDARs was used before ischemic exposure, the neuronal mitochondrial dysfunction was alleviated, suggesting that these aberrant deviations of NMDARs from basal levels led to mitochondrial dysfunction. Furthermore, when the antagonist of NR2B was administrated intracerebroventricularly at the sub-acute cerebral ischemia, the volume of cerebral infarct region was decreased and the neural functions were improved. To sum up, the ratio of NR2B-containing NMDARs is vital for mitochondrial homeostasis and then neuronal survival. NR2B-targeted intervention should be chosen at the sub-acute stage of cerebral ischemia.

Repositioning of Anti-Diabetic Drugs against Dementia: Insight from Molecular Perspectives to Clinical Trials

Insulin resistance as a hallmark of type 2 DM (T2DM) plays a role in dementia by promoting pathological lesions or enhancing the vulnerability of the brain. Numerous studies related to insulin/insulin-like growth factor 1 (IGF-1) signaling are linked with various types of dementia. Brain insulin resistance in dementia is linked to disturbances in Aβ production and clearance, Tau hyperphosphorylation, microglial activation causing increased neuroinflammation, and the breakdown of tight junctions in the blood-brain barrier (BBB). These mechanisms have been studied primarily in Alzheimer's disease (AD), but research on other forms of dementia like vascular dementia (VaD), Lewy body dementia (LBD), and frontotemporal dementia (FTD) has also explored overlapping mechanisms. Researchers are currently trying to repurpose anti-diabetic drugs to treat dementia, which are dominated by insulin sensitizers and insulin substrates. Although it seems promising and feasible, none of the trials have succeeded in ameliorating cognitive decline in late-onset dementia. We highlight the possibility of repositioning anti-diabetic drugs as a strategy for dementia therapy by reflecting on current and previous clinical trials. We also describe the molecular perspectives of various types of dementia through the insulin/IGF-1 signaling pathway.

Role of neurotrophic and growth factors in the rapid and sustained antidepressant actions of ketamine

The neurotrophic hypothesis of depression proposes that reduced levels of brain-derived neurotrophic factor (BDNF) and vascular endothelial growth factor (VEGF) contribute to neuronal atrophy or loss in the prefrontal cortex (PFC) and hippocampus and impaired hippocampal adult neurogenesis, which are associated with depressive symptoms. Chronic, but acute, treatment with typical monoaminergic antidepressants can at least partially reverse these deficits, in part via induction of BDNF and/or VEGF expression, consistent with their delayed onset of action. Ketamine, an N-methyl-d-aspartate receptor antagonist, exerts rapid and sustained antidepressant effects. Rodent studies have revealed that ketamine rapidly increases BDNF and VEGF release and/or expression in the PFC and hippocampus, which in turn increases the number and function of spine synapses in the PFC and hippocampal neurogenesis. Ketamine also induces the persistent release of insulin-like growth factor 1 (IGF-1) in the PFC of male mice. These neurotrophic effects of ketamine are associated with its rapid and sustained antidepressant effects. In this review, we first provide an overview of the neurotrophic hypothesis of depression and then discuss the role of BDNF, VEGF, IGF-1, and other growth factors (IGF-2 and transforming growth factor-β1) in the antidepressant effects of ketamine and its enantiomers. This article is part of the Special Issue on 'Ketamine and its Metabolites'.

The combination of Astragalus membranaceus and ligustrazine mitigates cerebral ischemia-reperfusion injury via regulating NR2B-ERK/CREB signaling

BACKGROUND AND PURPOSE

Cerebral ischemia-reperfusion (I/R) injury is a major factor underlying the high mortality and morbidity rates in stroke patients. Our previous study found that the combination of Astragalus membranaceus extract and ligustrazine (Ast+Lig) treatment could protect brain tissues against inflammation in rats with thrombolytic cerebral ischemia. Activation of N-methyl-D-aspartate receptors (NMDAR) is implicated in brain damage induced by cerebral I/R injury.

METHODS

We used in vivo and in vitro models of cerebral I/R injury for middle cerebral artery occlusion/reperfusion in mice and oxygen-glucose deprivation/reoxygenation in primary rat cerebral cortical neurons to evaluate the protective effects of Ast+Lig on cerebral I/R injury, and whether the protective mechanism was related to the regulation of NMDAR-ERK/CREB signaling.

RESULTS

Treatment with Ast+Lig, or MK-801 (an inhibitor of NMDAR) significantly ameliorated neurological deficits, decreased infarct volumes, suppressed neuronal damage and Ca²⁺ influx, and maintained the mitochondrial membrane potential in vivo and in vitro following cerebral I/R injury based on 2,3,5-triphenyl tetrazolium chloride staining, immunohistochemistry, and immunofluorescent staining. Furthermore, treatment with Ast+Lig evidently prevented the upregulation of NR2B, but not NR2A, in vivo and in vitro following cerebral I/R injury based on western blotting and reverse transcription-quantitative PCR analyses. Moreover, treatment with Ast+Lig significantly increased the phosphorylation of ERK and CREB, as well as increasing their mRNA expression levels in vivo and in vitro following cerebral I/R injury.

CONCLUSIONS

The overall results thus suggest that the Ast+Lig combination conferred neuroprotective properties against cerebral I/R injury via regulation of the NR2B-ERK/CREB signaling pathway.

The role of peptidyl-prolyl isomerase Pin1 in neuronal signaling in epilepsy

Epilepsy is a common symptom of many neurological disorders and can lead to neuronal damage that plays a major role in seizure-related disability. The peptidyl-prolyl isomerase Pin1 has wide-ranging influences on the occurrence and development of neurological diseases. It has also been suggested that Pin1 acts on epileptic inhibition, and the molecular mechanism has recently been reported. In this review, we primarily focus on research concerning the mechanisms and functions of Pin1 in neurons. In addition, we highlight the significance and potential applications of Pin1 in neuronal diseases, especially epilepsy. We also discuss the molecular mechanisms by which Pin1 controls synapses, ion channels and neuronal signaling pathways to modulate epileptic susceptibility. Since neurotransmitters and some neuronal signaling pathways, such as Notch1 and PI3K/Akt, are vital to the nervous system, the role of Pin1 in epilepsy is discussed in the context of the CaMKII-AMPA receptor axis, PSD-95-NMDA receptor axis, NL2/gephyrin-GABA receptor signaling, and Notch1 and PI3K/Akt pathways. The effect of Pin1 on the progression of epilepsy in animal models is discussed as well. This information will lead to a better understanding of Pin1 signaling pathways in epilepsy and may facilitate development of new therapeutic strategies.

Glutamate excitotoxicity: Potential therapeutic target for ischemic stroke

Glutamate-mediated excitotoxicity is an important mechanism leading to post ischemic stroke damage. After acute stroke, the sudden reduction in cerebral blood flow is most initially followed by ion transport protein dysfunction and disruption of ion homeostasis, which in turn leads to impaired glutamate release, reuptake, and excessive N-methyl-D-aspartate receptor (NMDAR) activation, promoting neuronal death. Despite extensive evidence from preclinical studies suggesting that excessive NMDAR stimulation during ischemic stroke is a central step in post-stroke damage, NMDAR blockers have failed to translate into clinical stroke treatment. Current treatment options for stroke are very limited, and there is therefore a great need to develop new targets for neuroprotective therapeutic agents in ischemic stroke to extend the therapeutic time window. In this review, we highlight recent findings on glutamate release, reuptake mechanisms, NMDAR and its downstream cellular signaling pathways in post-ischemic stroke damage, and review the pathological changes in each link to help develop viable new therapeutic targets. We then also summarize potential neuroprotective drugs and therapeutic approaches for these new targets in the treatment of ischemic stroke.

IGF-1 release in the medial prefrontal cortex mediates the rapid and sustained antidepressant-like actions of ketamine

Ketamine, an N-methyl-D-aspartate receptor antagonist, exerts rapid and sustained antidepressant actions. Preclinical studies demonstrated that the release of brain-derived neurotrophic factor (BDNF) and vascular endothelial growth factor in the medial prefrontal cortex (mPFC) is essential for the antidepressant-like effects of ketamine. However, the role of other neurotrophic factors in the antidepressant-like effects of ketamine has not been fully investigated. Since the intra-mPFC infusion of insulin-like growth factor 1 (IGF-1) reportedly produced antidepressant-like effects, the present study examined the role of endogenous intra-mPFC IGF-1 signaling in the antidepressant-like actions of ketamine. In vivo microdialysis showed that ketamine (10 and 30 mg/kg) significantly increased extracellular IGF-1 levels in the mPFC of male C57BL/6J mice for at least 5 h. Infusion of an IGF-1 neutralizing antibody (nAb; 160 ng/side) into the mPFC 15 min before or 2 h after ketamine injection blocked the antidepressant-like effects of ketamine in three different behavioral paradigms (forced swim, female urine sniffing, and novelty-suppressed feeding tests were conducted 1, 3 and 4 days post-ketamine, respectively). The ketamine-like antidepressant-like actions of the intra-mPFC infusion of BDNF (100 ng/side) and IGF-1 (50 ng/side) respectively were not blocked by co-infused IGF-1 nAb and BDNF nAb (200 ng/side). Moreover, intra-mPFC infusion of IGF-1 nAb 2 h post-ketamine blocked the antidepressant-like effects of ketamine in a murine lipopolysaccharide (LPS)-induced depression model. Intra-mPFC IGF-1 infusion also produced antidepressant-like effects in the LPS-challenged mice via mechanistic target of rapamycin complex 1 activation. These results suggest that persistent release of IGF-1, independently of BDNF, in the mPFC is essential for the antidepressant-like actions of ketamine.

Total Triterpenes of Wolfiporia cocos (Schwein.) Ryvarden & Gilb Exerts Antidepressant-Like Effects in a Chronic Unpredictable Mild Stress Rat Model and Regulates the Levels of Neurotransmitters, HPA Axis and NLRP3 Pathway

Purpose:Wolfiporia cocos is frequently used in traditional Chinese medicine to treat depression. However, antidepressant-like effects of the main active ingredients of Wolfiporia cocos, total triterpenes of Wolfiporia cocos (TTWC), are not well studied. This study aimed to investigate those effects and explore their specific mechanisms of action in depth.

Methods: Chemical components of TTWC were analyzed using LC-MS. Depression-like behavior in rats were induced by chronic unpredictable mild stress (CUMS). The suppressive effects of TTWC (60, 120, 240 mg/kg) against CUMS-induced depression-like behavior were evaluated using the forced swimming test (FST), open field test (OFT) and sucrose preference test (SPT). Levels of 5-hydroxytryptamine (5-HT), glutamate (GLU), corticotropin-releasing hormone (CRH), interleukin-1 beta (IL-1beta), interleukin-18 (IL-18), interleukin-6 (IL-6), and tumor necrosis factor-alpha (TNF-alpha) in different groups were determined by ELISA. Western blotting (WB) was used to detect the expression of NLRP3, ASC, pro-caspase-1, caspase-1, pro-IL-1beta, IL-1beta, pro-IL-18, and IL-18 in the prefrontal cortex. Additionally, the mRNA levels of NLRP3, ASC, caspase-1, IL-1beta and IL-18 were detected by RT-PCR.

Results: A total of 69 lanostane-type triterpene acids of TTWC were identified. The results showed that TTWC exhibited an antidepressant-like effect in CUMS rats, reversed the decreased sugar preference in the SPT, reduction of immobility time in the FST, reduced the rest time, increased the total moving distance in the OFT. TTWC increased 5-HT levels and decreased GLU levels in the hippocampus. Moreover, TTWC decreased CRH levels in serum, indicating the regulation of over-activation of the hypothalamic-pituitary-adrenal (HPA) axis. In addition, reduced serum levels of IL-1beta, IL-18, IL-6, and TNF-alpha. The WB results implied that TTWC inhibited the expression of NLRP3, ASC, caspase-1, IL-1beta, and IL-18 in the prefrontal cortex and enhanced the expression of pro-caspase-1, pro-IL-1beta, and pro-IL-18. Although most of the results were not significant, PCR results showed that TTWC inhibited the expression of NLRP3, ASC, caspase-1, IL-1beta, and IL-18 in the prefrontal cortex.

Conclusion: TTWC treatment exerted an antidepressant-like effect and regulates neurotransmitters, HPA axis and NLRP3 signaling pathway. These results indicated the potential of TTWC in preventing the development of depression.

Research Progress on Neuroprotection of Insulin-like Growth Factor-1 towards Glutamate-Induced Neurotoxicity

Insulin-like growth factor-1 (IGF-1) and its binding proteins and receptors are widely expressed in the central nervous system (CNS), proposing IGF-1-induced neurotrophic actions in normal growth, development, and maintenance. However, while there is convincing evidence that the IGF-1 system has specific endocrine roles in the CNS, the concept is emerging that IGF-I might be also important in disorders such as ischemic stroke, brain trauma, Alzheimer’s disease, epilepsy, etc., by inducing neuroprotective effects towards glutamate-mediated excitotoxic signaling pathways. Research in rodent models has demonstrated rescue of pathophysiological and behavioral abnormalities when IGF-1 was administered by different routes, and several clinical studies have shown safety and promise of efficacy in neurological disorders of the CNS. Focusing on the relationship between IGF-1-induced neuroprotection and glutamate-induced excitatory neurotoxicity, this review addresses the research progress in the field, intending to provide a rationale for using IGF-I clinically to confer neuroprotective therapy towards neurological diseases with glutamate excitotoxicity as a common pathological pathway.

Insulin-Like Growth Factor-1 Differentially Modulates Glutamate-Induced Toxicity and Stress in Cells of the Neurogliovascular Unit

The age-related reduction in circulating levels of insulin-like growth factor-1 (IGF-1) is associated with increased risk of stroke and neurodegenerative diseases in advanced age. Numerous reports highlight behavioral and physiological deficits in blood-brain barrier function and neurovascular communication when IGF-1 levels are low. Administration of exogenous IGF-1 reduces the extent of tissue damage and sensorimotor deficits in animal models of ischemic stroke, highlighting the critical role of IGF-1 as a regulator of neurovascular health. The beneficial effects of IGF-1 in the nervous system are often attributed to direct actions on neurons; however, glial cells and the cerebrovasculature are also modulated by IGF-1, and systemic reductions in circulating IGF-1 likely influence the viability and function of the entire neuro-glio-vascular unit. We recently observed that reduced IGF-1 led to impaired glutamate handling in astrocytes. Considering glutamate excitotoxicity is one of the main drivers of neurodegeneration following ischemic stroke, the age-related loss of IGF-1 may also compromise neural function indirectly by altering the function of supporting glia and vasculature. In this study, we assess and compare the effects of IGF-1 signaling on glutamate-induced toxicity and reactive oxygen species (ROS)-produced oxidative stress in primary neuron, astrocyte, and brain microvascular endothelial cell cultures. Our findings verify that neurons are highly susceptible to excitotoxicity, in comparison to astrocytes or endothelial cells, and that a prolonged reduction in IGFR activation increases the extent of toxicity. Moreover, prolonged IGFR inhibition increased the susceptibility of astrocytes to glutamate-induced toxicity and lessened their ability to protect neurons from excitotoxicity. Thus, IGF-1 promotes neuronal survival by acting directly on neurons and indirectly on astrocytes. Despite increased resistance to excitotoxic death, both astrocytes and cerebrovascular endothelial cells exhibit acute increases in glutamate-induced ROS production and mitochondrial dysfunction when IGFR is inhibited at the time of glutamate stimulation. Together these data highlight that each cell type within the neuro-glio-vascular unit differentially responds to stress when IGF-1 signaling was impaired. Therefore, the reductions in circulating IGF-1 observed in advanced age are likely detrimental to the health and function of the entire neuro-glio-vascular unit.

Insulin-like growth factor 1 promotes neurological functional recovery after spinal cord injury through inhibition of autophagy via the PI3K/Akt/mTOR signaling pathway

Spinal cord injury (SCI) is a serious trauma; however, the mechanisms underlying the role of insulin-like growth factor 1 (IGF-1) in autophagy following SCI remain to be elucidated. The present study aimed to investigate the therapeutic effect of IGF-1 on SCI and to determine whether IGF-1 regulates autophagy via the PI3K/Akt/mTOR signaling pathway. SH-SY5Y neuroblastoma cells were assigned to the H₂O₂, IGF-1 and control groups to investigate subsequent neuron injury in vitro. An MTT assay was performed to evaluate cell survival. In addition, Sprague-Dawley rats were randomly assigned to SCI, SCI + IGF-1 and sham groups, and Basso-Beatlie-Bresnahan scores were assessed to determine rat neurological function. Western blotting was used to analyze the autophagy level and the activation of the PI3K/Akt/mTOR signaling pathway. Cell survival was increased significantly in the IGF-1 group compared with the control group in vitro (P<0.05). Furthermore, neurological function was improved in the SCI + IGF-1 group compared with the control group in vivo (P<0.05). The western blotting results further demonstrated that LC3II/LC3I expression was increased in the IGF-1 group compared with the sham group in vivo and compared with the control group in vitro (both P<0.05). In the SCI + IGF-1 group, the expression levels of PI3K, phosphorylated (p)-Akt and p-mTOR were higher compared with those in the sham and SCI groups in vivo (P<0.05). Moreover, in the IGF-1 group, the expression levels of p-Akt and p-mTOR were higher compared with the control and the H₂O₂ groups in vitro (P<0.05). Collectively, the results of the present study suggested that IGF-1 promoted functional recovery in rats following SCI through neuroprotective effects. Furthermore, the underlying mechanism may involve activation of the PI3K/Akt/mTOR signaling pathway, followed by inhibition of autophagy. However, further investigation into the association between IGF-1-regulated autophagy and the activation of different subtypes of PI3K is required.

Attenuation of Pb-induced Aβ generation and autophagic dysfunction via activation of SIRT1: Neuroprotective properties of resveratrol

This study examined the neuroprotective properties of resveratrol (Res) and its target sirtuin1 (SIRT1) against lead (Pb)-mediated toxicity and discovered that both resveratrol treatment and SIRT1 overexpression restored blocked autophagic flux as well as reduced β-amyloid (Aβ) contents. Four-week-old male C57BL/6 mice were employed to consumed 0.2% Pb(Ac)₂ solution or deionized water for 3 months followed by 12 months of Res (50 mg/kg BW) or vehicle gavage. In in vitro study, SH-SY5Y cells were pretreated with the SIRT1 activator SRT1720 (2 μM) or the inhibitor EX527 (2 μM) for 2 h, then 25 μM of Pb(Ac)₂ was added and incubated for 48 h. Western blotting, RT-qPCR, enzyme-linked immunosorbent assay (ELISA), and Lyso-Tracker Red Staining were next used to estimate the potential alterations of the autophagic pathway as well as BACE1-mediated amyloid processing in response to Pb exposure, respectively. Our data revealed that Res treatment or SIRT1 activation resisted the induction of autophagy by Pb exposure through inhibition of LC3 and Beclin-1 expression and promoted the degradation of Aβ and Tau phosphorylation. Besides, the SIRT1 activator (SRT1720) downregulated the expression of BACE1, the rate-limiting enzyme for Aβ production, by inhibiting the activation of nuclear factor-κB (NF-κB) in Pb-treated SH-SY5Y cells, which resulted in reduced Aβ production. Collectively, we verified the role of Res-SIRT1-autophagy as well as the SIRT1-NF-κB-BACE1 pathway in Pb-induced neuronal cell injury by in vivo or in vitro models. Our findings further elucidate the important role of SIRT1 and Res in counteracting Pb neurotoxicity, which may provide new interventions and targets for the subsequent treatment of neurodegenerative diseases.

Preclinical and clinical evidence of IGF-1 as a prognostic marker and acute intervention with ischemic stroke

Ischemic strokes are highly prevalent in the elderly population and are a leading cause of mortality and morbidity worldwide. The risk of ischemic stroke increases in advanced age, corresponding with a noted decrease in circulating insulin growth factor-1 (IGF-1). IGF-1 is a known neuroprotectant involved in embryonic development, neurogenesis, neurotransmission, cognition, and lifespan. Clinically, several studies have shown that reduced levels of IGF-1 correlate with increased mortality rate, poorer functional outcomes, and increased morbidities following an ischemic stroke. In animal models of ischemia, administering exogenous IGF-1 using various routes of administration (intranasal, intravenous, subcutaneous, or topical) at various time points prior to and following insult attenuates neurological damage and accompanying behavioral changes caused by ischemia. However, there are some contrasting findings in select clinical and preclinical studies. This review discusses the role of IGF-1 as a determinant factor of ischemic stroke outcomes, both within the clinical settings and preclinical animal models. Furthermore, the review provides insight on the role of IGF-1 in mechanisms and cellular processes that contribute to stroke damage.

Nutritional interventions for spinal cord injury: preclinical efficacy and molecular mechanisms

Spinal cord injury (SCI) is a debilitating condition that leads to motor, sensory, and autonomic impairments. Its intrinsic pathophysiological complexity has hindered the establishment of effective treatments for decades. Nutritional interventions (NIs) for SCI have been proposed as a route to circumvent some of the problems associated with this condition. Results obtained in animal models point to a more holistic effect, rather than to specific modulation, of several relevant SCI pathophysiological processes. Indeed, published data have shown NI improves energetic imbalance, oxidative damage, and inflammation, which are promoters of improved proteostasis and neurotrophic signaling, leading ultimately to neuroprotection and neuroplasticity. This review focuses on the most well-documented Nis. The mechanistic implications and their translational potential for SCI are discussed.

Abnormal Insulin-like Growth Factor 1 Signaling Regulates Neuropathic Pain by Mediating the Mechanistic Target of Rapamycin-Related Autophagy and Neuroinflammation in Mice

Neuropathic pain is a chronic condition with little specific treatment. Insulin-like growth factor 1 (IGF1), interacting with its receptor, IGF1R, serves a vital role in neuronal and brain functions such as autophagy and neuroinflammation. Yet, the function of spinal IGF1/IGF1R in neuropathic pain is unclear. Here, we examined whether and how spinal IGF1 signaling affects pain-like behaviors in mice with chronic constriction injury (CCI) of the sciatic nerve. To corroborate the role of IGF1, we injected intrathecally IGF1R inhibitor (nvp-aew541) or anti-IGF1 neutralizing antibodies. We found that IGF1 (derived from astrocytes) in the lumbar cord increased along with the neuropathic pain induced by CCI. IGF1R was predominantly expressed on neurons. IGF1R antagonism or IGF1 neutralization attenuated pain behaviors induced by CCI, relieved mTOR-related suppression of autophagy, and mitigated neuroinflammation in the spinal cord. These findings reveal that the abnormal IGF1/IGF1R signaling contributes to neuropathic pain by exacerbating autophagy dysfunction and neuroinflammation.

Cellular Effects of Rhynchophylline and Relevance to Sleep Regulation

Uncaria rhynchophylla is a plant highly used in the traditional Chinese and Japanese medicines. It has numerous health benefits, which are often attributed to its alkaloid components. Recent studies in humans show that drugs containing Uncaria ameliorate sleep quality and increase sleep time, both in physiological and pathological conditions. Rhynchophylline (Rhy) is one of the principal alkaloids in Uncaria species. Although treatment with Rhy alone has not been tested in humans, observations in rodents show that Rhy increases sleep time. However, the mechanisms by which Rhy could modulate sleep have not been comprehensively described. In this review, we are highlighting cellular pathways that are shown to be targeted by Rhy and which are also known for their implications in the regulation of wakefulness and sleep. We conclude that Rhy can impact sleep through mechanisms involving ion channels, N-methyl-d-aspartate (NMDA) receptors, tyrosine kinase receptors, extracellular signal-regulated kinases (ERK)/mitogen-activated protein kinases (MAPK), phosphoinositide 3-kinase (PI3K)/RAC serine/threonine-protein kinase (AKT), and nuclear factor-kappa B (NF-κB) pathways. In modulating multiple cellular responses, Rhy impacts neuronal communication in a way that could have substantial effects on sleep phenotypes. Thus, understanding the mechanisms of action of Rhy will have implications for sleep pharmacology.

Dysregulation of IGF-1/GLP-1 signaling in the progression of ALS: potential target activators and influences on neurological dysfunctions

The prominent causes for motor neuron diseases like ALS are demyelination, immune dysregulation, and neuroinflammation. Numerous research studies indicate that the downregulation of IGF-1 and GLP-1 signaling pathways plays a significant role in the progression of ALS pathogenesis and other neurological disorders. In the current review, we discussed the dysregulation of IGF-1/GLP-1 signaling in neurodegenerative manifestations of ALS like a genetic anomaly, oligodendrocyte degradation, demyelination, glial overactivation, immune deregulation, and neuroexcitation. In addition, the current review reveals the IGF-1 and GLP-1 activators based on the premise that the restoration of abnormal IGF-1/GLP-1 signaling could result in neuroprotection and neurotrophic effects for the clinical-pathological presentation of ALS and other brain diseases. Thus, the potential benefits of IGF-1/GLP-1 signal upregulation in the development of disease-modifying therapeutic strategies may prevent ALS and associated neurocomplications.

Xiaoyaosan Alleviates Hippocampal Glutamate-Induced Toxicity in the CUMS Rats via NR2B and PI3K/Akt Signaling Pathway

Purpose: It is revealed that Xiaoyaosan could reduce glutamate level in the hippocampus of depressed rats, whose metabolism leads to the pathophysiology of depression. However, the underlying mechanism remains unclear. This study aims to explore the effect of Xiaoyaosan on glutamate metabolism, and how to regulate the excitatory injury caused by glutamate. Methods: Rats were induced by chronic unpredictable mild stress, then divided into control, vehicle (distilled water), Xiaoyaosan, fluoxetine, vehicle (DMSO), Xiaoyaosan + Ly294002 and Ly294002 groups. Ly294002 was microinjected into the lateral ventricular catheterization at 5 mM. Xiaoyaosan (2.224 g/kg) and fluoxetine (2.0 mg/kg) were orally administered for three weeks. The open field test (OFT), forced swimming test (FST), and sucrose preference test (SPT) were used to assess depressive behavior. The glutamate and corticosterone (CORT) levels were detected by ELISA. Western blot, immunochemistry or immunofluorescence were used to detect the expressions of NR2B, MAP2, PI3K and P-AKT/Akt in the hippocampal CA1 region. The mRNA level of MAP2, NR2B and PI3K were detected by RT-qPCR. Results: Compared to the rats in control group, body weight and food intake of CUMS rats was decreased. CUMS rats also showed depression-like behavior as well as down regulate the NR2B and PI3K/Akt signaling pathway. Xiaoyaosan treatments could increase food intake and body weight as well as improved time spent in the central area, total distance traveled in the OFT. Xiaoyaosan could also decrease the immobility time as well as increase the sucrose preference in SPT. Moreover, xiaoyaosan decreased the level of glutamate in the hippocampal CA1 region and serum CORT in CUMS rats. Furthermore, xiaoyaosan improved the expression of MAP2 as well as increased the expression of NR2B, PI3K and the P-AKT/AKT ratio in the hippocampal CA1 region in the CUMS rats. Conclusion: Xiaoyaosan treatment can exert the antidepressant effect by rescuing hippocampal neurons loss induced by the glutamate-mediated excitotoxicity in CUMS rats. The underlying pathway maybe through NR2B and PI3K/Akt signaling pathways. These results may suggest the potential of Xiaoyaosan in preventing the development of depression.

Therapeutic modulation of the phosphatidylinositol 3-kinases (PI3K) pathway in cerebral ischemic injury

The cerebral ischemic reperfusion injury may leads to morbidity and mortality in patients. phosphatidylinositol 3-kinase (PI3K) signaling pathway has been believed to work in association with its downstream targets, other receptors, and pathways that may offer antioxidant, anti-inflammatory, anti-apoptotic effects, neuroprotective role in neuronal excitotoxicity. This review elaborates the mechanistic interventions of the PI3K pathway in cerebral ischemic injury in context to nuclear factor erythroid 2-related factor 2 (Nrf2) regulation, Hypoxia-inducible factor 1 signaling (HIF-1), growth factors, Endothelial NOS (eNOS) proinflammatory cytokines, Erythropoietin (EPO), Phosphatase and tensin homologous protein of chromosome 10 gene (PTEN) signaling, NF-κB/Notch signaling, c-Jun N-terminal kinase (JNK) and Glycogen synthase kinase-3β (GSK-3β) signaling pathway. Evidences showing the activation of PI3K inhibits apoptotic pathway, which results in its neuroprotective effect in ischemic injury. Despite discussing the therapeutic role of the PI3K pathway in treating cerebral ischemic injury, the review also enlighten the selective modulation of PI3K pathway with activators and inhibitors which may provide promising results in clinical and preclinical settings.

Spinal muscular atrophy: Broad disease spectrum and sex-specific phenotypes

Spinal muscular atrophy (SMA) is one of the major genetic disorders associated with infant mortality. More than 90% of cases of SMA result from deletions of or mutations in the Survival Motor Neuron 1 (SMN1) gene. SMN2, a nearly identical copy of SMN1, does not compensate for the loss of SMN1 due to predominant skipping of exon 7. The spectrum of SMA is broad, ranging from prenatal death to infant mortality to survival into adulthood. All tissues, including brain, spinal cord, bone, skeletal muscle, heart, lung, liver, pancreas, gastrointestinal tract, kidney, spleen, ovary and testis, are directly and/or indirectly affected in SMA. Accumulating evidence on impaired mitochondrial biogenesis and defects in X chromosome-linked modifying factors, coupled with the sexual dimorphic nature of many tissues, point to sex-specific vulnerabilities in SMA. Here we review the role of sex in the pathogenesis of SMA.

N-Adamantyl-4-methylthiazol-2-amine suppresses glutamate-induced autophagic cell death via PI3K/Akt/mTOR signaling pathways in cortical neurons

We recently reported that N-adamantyl-4-methylthiazol-2-amine (KHG26693) attenuates glutamate-induced oxidative stress and inflammation in the brain. In this study, we investigated KHG 26693 as a therapeutic agent against glutamate-induced autophagic death of cortical neurons. Treatment with KHG26693 alone did not affect the viability of cultured cortical neurons but was protective against glutamate-induced cytotoxicity in a concentration-dependent manner. KHG26693 attenuated the glutamate-induced increase in protein levels of LC3, beclin-1, and p62. Whereas glutamate decreased the phosphorylation of PI3K, Akt, and mTOR, these levels were restored by treatment with KHG26693. These results suggest that KHG26693 inhibits glutamate-induced autophagy by regulating PI3K/Akt/mTOR signaling. Finally, KHG26693 treatment also attenuated glutamate-induced increases in reactive oxygen species, glutathione, glutathione peroxidase, and superoxide dismutase levels in cortical neurons, indicating that KHG26693 also protects cortical neurons against glutamate-induced autophagy by regulating the reactive oxygen species scavenging system.

Autophagy associated with the efficacy of valproic acid in PTZ-induced epileptic rats

Valproic acid (VPA) is a widely used antiepileptic drugs. Patients who are non-responsive to VPA often present to the clinic; however, the mechanism of resistance is unclear. In this study, we found that responder and non-responder pentylenetetrazole-induced chronic epileptic rats had no significant differences in VPA concentrations in their plasma and brain tissues. Furthermore, through an RNA-sequence method, we identified 334 differentially expressed genes between VPA-responsive and non-responsive rats, while 21 pathways were enriched. Interestingly, 16 pathways, including the phagosome pathway, were commonly enriched compared to those in patients. We used transmission electron microscopy and immunofluorescence microscopy to further assess the level of autophagy in responder and non-responder rats. Non-responders had more autophagic vacuoles and an increased level of LC3B expression. Furthermore, epileptic rats that were previously administered 3-methyadenine (an inhibitor of autophagy) exhibited a slight increase in VPA efficacy. In conclusion, autophagy was associated with the efficacy of VPA.

Lead exposure induces cell autophagy via blocking the Akt/mTOR signaling in rat astrocytes

Lead is a main threat to human health due to its neurotoxicity and the astrocyte is known to be a common deposit site of lead in vivo. However, the detailed mechanisms related to lead exposure in the astrocytes were unclear. In order to deeply investigate this issue, we used Sprague-Dawley (SD) rats and astrocytes isolated from the hippocampus of SD rats to establish the lead-exposed animal and cell models through treating with lead acetate. The expression levels of GFAP, LC3, and p62 in the rat hippocampus were detected by immunofluorescence and Western blot after lead exposure. The effects of autophagy on lead-exposed astrocytes were studied by further autophagy inhibitor 3-methyladenine (3-MA) induction. Transmission electron microscopy was used to observe autophagosomes in astrocytes after lead acetate treatment, followed by assessing related autophagy protein markers. In addition, some inflammatory cytokines and oxidative stress markers were also evaluated after lead exposure and 3-MA administration. We found that lead exposure induced activation of astrocytes, as evidenced by increased GFAP levels and GFAP-positive staining cells in the rat hippocampus. Moreover, lead exposure induced autophagy in astrocytes, as evidenced by increased LC3II and Beclin 1 protein levels and decreased p62 expression in both the rat hippocampus and astrocytes, and it was confirmed that this autophagy was activated through blocking the downstream Akt/target of the rapamycin (mTOR) pathway in astrocytes. Furthermore, it was shown that treatment of lead acetate increased the release of tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β), and the accumulation of malondialdehyde (MDA) and myeloperoxidase (MPO) in astrocytes, which could be alleviated by further 3-MA induction. Therefore, we conclude that lead exposure can induce the autophagy of astrocytes via blocking the Akt/mTOR pathway, leading to accelerated release of inflammatory factors and oxidative stress indicators in astrocytes.

The putative etiology and prevention of autism

Since the initial psychological report by Leo Kanner in 1943, relatively little formal biochemical/neurological research on the cause of autism, other than peripheral searches for genomic mutations, had been carried until the end of the 20th century. As a result of studies on twin sets and the conclusion that autism was largely a hereditary defect, numerous investigations have sought various genetic faults in particular. However, such studies were able to reveal a plausible etiology for this malady in only a small percentage of instances. Key bio-molecular characteristics of this syndrome have been uncovered when the potential roles of the glia were studied in depth. Findings related to biochemical deficiencies appearing early in the newborn, such as depressed IGF-1 (insulin-like growth factor #1) in neurogenesis/myelination, are becoming emphasized in many laboratories. Progress leading to timely diagnoses and subsequent prevention of central nervous system dysconnectivity now seems plausible. The tendency for an infant to develop autism may currently be determinable and preventable before irreversible psychosocial disturbances become established. These discussions about glial function will be inter-spersed with comments about their apparent relevance to autism. The concluding portion of this presentation will be a detailed review and summation of this diagnosis and prevention proposition.

Downregulation of CDK5 Restores Sevoflurane-Induced Cognitive Dysfunction by Promoting SIRT1-Mediated Autophagy

An increasing number of studies have found that use of traditional anesthetics may lead to cognitive impairment of the immature brain. Our previous studies verified that cyclin-dependent kinase 5 (CDK5) plays a role in sevoflurane-induced cognitive dysfunction. Autophagy was shown to protect against anesthesia-induced nerve injury. Therefore, the current study aimed to ascertain if autophagy participates in anesthesia-induced neurotoxicity. In this study, primary hippocampal neurons were isolated and utilized for experiments in vitro. We also performed in vivo experiments with 6-day-old wild-type mice treated with or without roscovitine (Rosc, a CDK5 inhibitor) or 3-methyladenine (3-Ma, an autophagy inhibitor) after exposure to sevoflurane. We used the Morris water maze to analyze cognitive function. Immunohistochemical staining was used to assess pathologic changes in the hippocampus. The results showed that suppressing CDK5 reversed sevoflurane-induced nerve cell apoptosis both in vivo and in vitro and demonstrated that inhibits CDK5 activation promoted Sirtuin 1 (Sirt1) expression, which functions importantly in induced autophagy activation. Suppression of Sirt1 expression inhibited the protective effect of Rosc on sevoflurane-induced nerve injury by inhibiting autophagy activation. Our in vivo experiments also found that pretreatment with 3-Ma attenuated the protective effect of Rosc on sevoflurane-induced nerve injury and cognitive dysfunction. We conclude that inhibits CDK5 activation restored sevoflurane-induced cognitive dysfunction by promoting Sirt1-mediated autophagy.

Activation of G protein-coupled receptor 30 protects neurons by regulating autophagy in astrocytes

Ischemic stroke leads to neuronal damage induced by excitotoxicity, inflammation, and oxidative stress. Astrocytes play diverse roles in stroke and ischemia-induced inflammation, and autophagy is critical for maintaining astrocytic functions. Our previous studies showed that the activation of G protein-coupled receptor 30 (GPR30), an estrogen membrane receptor, protected neurons from excitotoxicity. However, the role of astrocytic GPR30 in maintaining autophagy and neuroprotection remained unclear. In this study, we found that the neuroprotection induced by G1 (GPR30 agonist) in wild-type mice after a middle cerebral artery occlusion was completely blocked in GPR30 conventional knockout (KO) mice but partially attenuated in astrocytic or neuronal GPR30 KO mice. In cultured primary astrocytes, glutamate exposure induced astrocyte proliferation and decreased astrocyte autophagy by activating mammalian target of rapamycin (mTOR) and c-Jun N-terminal kinase (JNK) and inhibiting p38 mitogen-activated protein kinase (MAPK) pathway. G1 treatment restored autophagy to its basal level by regulating the p38 pathway but not the mTOR and JNK signaling pathways. Our findings revealed a key role of GPR30 in neuroprotection via the regulation of astrocyte autophagy and support astrocytic GPR30 as a potential drug target against ischemic brain damage.

Activation of G-Protein-Coupled Receptor 30 Protects Neurons against Excitotoxicity through Inhibiting Excessive Autophagy Induced by Glutamate

Autophagy is a protecting intracellular pathway to transmit unnecessary or dysfunctional components to the lysosome for degeneration. Autophagic imbalance is connected with neurodegeneration. Neurodegenerative diseases including Parkinson's disease, Alzheimer's disease, and Huntington's disease are closely related to excitotoxicity and neuronal loss. Activation of G-protein-coupled receptor 30 (GPR30), an estrogen membrane receptor, protects neurons from excitotoxicity-induced cell death. However, whether autophagy is involved in the neuroprotective effect of GPR30 activation is not well-known. In this study, methyl thiazolyl tetrazolium (MTT), Western blot, monodansylcadaverine (MDC) staining, and immunofluorescent staining were employed to detect the role of autophagy in cultured primary cortical neurons after glutamate exposure and G1 treatment. Pretreatment of G1 (GPR30 specific agonist) reduced neuronal loss through inhibiting excessive autophagy induced by glutamate exposure, which was blocked by GPR30 antagonist G15, phosphatidylinositol-3-kinase (PI3K), and the mammalian target of rapamycin (mTOR) inhibitors. These data suggest that GPR30 protects neurons from cell loss primarily by modulating PI3K-AKT-mTOR signaling pathway. In addition, G1 alone did not affect the basal autophagy and cell viability. We conclude that GPR30 activation reduces glutamate-induced excessive autophagy in neurons and protects neurons against excitotoxicity.

IGF-1 alleviates serum IgG-induced neuronal cytolysis through PI3K signaling in children with opsoclonus-myoclonus syndrome and neuroblastoma

BACKGROUND

Opsoclonus-myoclonus syndrome (OMS) is a rare neurological disorder, usually accompanied by neuroblastoma (NB). There is no targeted treatment and animal model of OMS. We aimed to investigate whether insulin-like growth factor 1 (IGF-1)/phosphoinositide 3-kinase (PI3K) signaling alleviates neuronal cytolysis in pediatric OMS.

METHODS

Cultured rat cerebral cortical neurons and cerebellar neurons were incubated with sera or IgG isolated from sera of children with OMS and NB. Cytolysis and PI3K expression were measured by the lactate dehydrogenase assay and enzyme-linked immunosorbent assay, respectively. Using inhibitors and activators, the effects of IGF-1 and PI3K on cytolysis were investigated.

RESULTS

The incubation of sera or IgG from children with OMS and NB increased cytolysis in not only cerebellar neurons, but also cerebral cortical neurons. Furthermore, the IGF-1 receptor antagonist NVP-AEW541 exaggerated cytolysis in children with OMS and NB. IGF-1 alleviated cytolysis, which was blocked by the PI3K inhibitor LY294002. Additionally, sera or IgG from children with OMS and NB compensatively elevated PI3K expression. LY294002 exacerbated cytolysis; whereas, the PI3K activator 740 Y-P suppressed cytolysis.

CONCLUSION

IGF-1/PI3K signaling alleviates the cytolysis of cultured neurons induced by serum IgG from children with OMS and NB, which may be innovation therapy targets.

CDKL5 deficiency predisposes neurons to cell death through the deregulation of SMAD3 signaling

CDKL5 deficiency disorder (CDD) is a rare encephalopathy characterized by early onset epilepsy and severe intellectual disability. CDD is caused by mutations in the X-linked cyclin-dependent kinase-like 5 (CDKL5) gene, a member of a highly conserved family of serine-threonine kinases. Only a few physiological substrates of CDKL5 are currently known, which hampers the discovery of therapeutic strategies for CDD. Here, we show that SMAD3, a primary mediator of TGF-β action, is a direct phosphorylation target of CDKL5 and that CDKL5-dependent phosphorylation promotes SMAD3 protein stability. Importantly, we found that restoration of the SMAD3 signaling through TGF-β1 treatment normalized defective neuronal survival and maturation in Cdkl5 knockout (KO) neurons. Moreover, we demonstrate that Cdkl5 KO neurons are more vulnerable to neurotoxic/excitotoxic stimuli. In vivo treatment with TGF-β1 prevents increased NMDA-induced cell death in hippocampal neurons from Cdkl5 KO mice, suggesting an involvement of the SMAD3 signaling deregulation in the neuronal susceptibility to excitotoxic injury of Cdkl5 KO mice. Our finding reveals a new function for CDKL5 in maintaining neuronal survival that could have important implications for susceptibility to neurodegeneration in patients with CDD.

FABP5 regulates the proliferation of clear cell renal cell carcinoma cells via the PI3K/AKT signaling pathway

Clear cell renal cell carcinoma (ccRCC) has been associated with one of the highest mortality rates among all cancers. Fatty acid binding proteins (FABPs) are 14‑15 kDa proteins that are highly abundant in the cytosol of most tissues. FABP5, a member of the FABP family, has been observed to promote tumor cell growth in numerous cancer types. In order to investigate the function of FABP5 in ccRCC cells in the present study, RNA sequencing data from The Cancer Genome Atlas were analyzed to determine the expression levels of FABP5 in ccRCC patient samples. Survival and Cox regression analyses were performed to measure the association between FABP5 expression and clinicopathological features of patients with ccRCC. Subsequent in vitro experiments downregulated or overexpressed FABP5 in Caki‑1 and 786O ccRCC cells using lentiviral vectors to evaluate cell proliferation ability, and a xenograft transplantation model was established to examine the effect of FABP5 on tumorigenesis in vivo. The results demonstrated that FABP5 expression was significantly upregulated in samples from patients with ccRCC when compared with normal tissue samples. High FABP5 expression was also significantly correlated with tumor and metastasis classifications and predicted poor survival in patients with ccRCC. In ccRCC cells, silencing of FABP5 significantly inhibited cell proliferation, while overexpression of FABP5 promoted cell proliferation when compared to the respective controls. In addition, treatment with the phosphatidylinositol‑4,5‑bisphosphate 3‑kinase (PI3K)/AKT inhibitor, LY294002, attenuated the pro‑proliferative effects of exogenous FABP5 expression in Caki‑1 and 786O cells. This indicated that the PI3K/AKT signaling pathway may be partially involved in the FABP5‑mediated increase in ccRCC cell proliferation. Furthermore, FABP5 was observed to regulate tumor growth in nude mice in vivo. In conclusion, the results of the present study suggest that FABP5 may exert a pro‑proliferative role in ccRCC and may be associated with malignant progression and tumorigenesis.

Autophagy in Alzheimer's disease and promising modulatory effects of herbal medicine

Alzheimer's disease (AD) is a progressive and unremitting neurodegenerative disorder characterized by memory loss and cognitive impairment. It affects the quality of life of victims severely. The prevalence of AD has been increasing in recent years. Therefore, it is of great importance to elucidate the pathogenesis of AD and find out effective therapeutic approaches. Autophagy, a primary intracellular way of degrading aggregated proteins and damaged organelles, has been discovered to be involved in the pathological changes of AD. In the last few years, much progress has been made in finding autophagy regulators from natural products, providing new insights to develop treatment strategy for AD by targeting autophagy. In the present review, we provided an overview of the recent research progress regarding the function role of autophagy in AD, the regulation mechanisms of autophagy-lysosomal pathway as well as therapeutic potential of herbal medicine on AD by targeting autophagy.

NLRP3 inflammasome in NMDA-induced retinal excitotoxicity

N-methyl-D-aspartate (NMDA)-induced excitotoxicity is an acute form of experimental retinal injury as a result of overactivation of glutamate receptors. NLRP3 (nucleotide-binding domain, leucine-rich-repeat containing family, pyrin domain containing-3) inflammasome, one of the most studied sensors of innate immunity, has been reported to play a critical role in retinal neurodegeneration with controversial implications regarding neuroprotection and cell death. Thus far, it has not been elucidated whether NMDA-mediated excitotoxicity can trigger NLRP3 inflammasome in vivo. Moreover, it is unknown if NLRP3 is beneficial or detrimental to NMDA-mediated retinal cell death. Here, we employed a murine model of NMDA-induced retinal excitotoxicity by administering 100 nmoles of NMDA intravitreally, which resulted in massive TUNEL⁺ (TdT-dUTP terminal nick-end labelling) cell death in all retinal layers and especially in retinal ganglion cells (RGCs) 24 h post injection. NMDA insult in the retina potentiates macrophage/microglia cell infiltration, primes the NLRP3 inflammasome in a transcription-dependent manner and induces the expression of interleukin-1β (IL-1β). However, despite NLRP3 inflammasome upregulation, systemic deletion of Nlrp3 or Casp1 (caspase-1) did not significantly alter the NMDA-induced, excitotoxicity-mediated TUNEL⁺ retinal cell death at 24 h (acute phase). Similarly, the deletion of the two aforementioned genes did not alter the survival of the Brn3a⁺ (brain-specific homeobox/POU domain protein 3A) RGCs in a significant way at 3- or 7-days post injection (long-term phase). Our results indicate that NMDA-mediated retinal excitotoxicity induces immune cell recruitment and NLRP3 inflammasome activity even though inflammasome-mediated neuroinflammation is not a leading contributing factor to cell death in this type of retinal injury.

CSF nerve growth factor (β-NGF) is increased but CSF insulin-like growth factor-(IGF-1) is normal in children with tuberous sclerosis and infantile spasms

Tuberous sclerosis is associated with epilepsy that is often refractory. We examined cerebrospinal fluid (CSF) concentrations for neurotrophins, nerve growth factor (β-NGF) and insulin-like growth factor (IGF-1) in children with infantile spasms between 1997 and 2010. We classified the patients as follows: tuberous sclerosis (n = 5), cryptogenic spasms (n = 6), postinfectious spasms (n = 5) and other symptomatic spasms (n = 22). We had 22 age- and sex-matched controls for CSF-NGF and 14 for CSF-IGF-1. The median of CSF-NGF was higher in those with tuberous sclerosis, 56 (minimum-maximum, 8.0-131) ng/L, in relative to age- and sex-matched controls, 6.7 (0.0-22) ng/L, and symptomatic infantile spasms, 0.0 (0.0-4.5) ng/L or cryptogenic cases of infantile spasms, 6.2 (3.9-8.8) ng/L, respectively. CSF-NGF were highest in children with postinfectious aetiology, 408 (89-778) ng/L. CSF-IGF-1 of tuberous sclerosis, 0.65 (0.35-0.98) μg/L, did not differ from the cryptogenic spasms, 0.68 (0.32-0.87) μg/L, or from age- and sex-matched controls 0.52 (0.22-0.77) μg/L. Patients with tuberous sclerosis and cryptogenic spasms had normal development prior the ACTH therapy. We suggest that increased CSF-NGF might indicate a persistent activation of inflammatory pathways in cortical tubers in tuberous sclerosis and this would reflect in CSF concentrations.

The dual role of KCNQ/M channels upon OGD or OGD/R insults in cultured cortical neurons of mice: Timing is crucial in targeting M-channels against ischemic injur ies

KCNQ/M potassium channels play a vital role in neuronal excitability; however, it is required to explore their pharmacological modulation on N-Methyl- d-aspartic acid receptors (NMDARs)-mediated glutamatergic transmission of neurons upon ischemic insults. In the current study, both presynaptic glutamatergic release and activities of NMDARs were measured by NMDAR-induced miniature excitatory postsynaptic currents (mEPSCs) in cultured cortical neurons of C57 mice undergoing oxygen and glucose deprivation (OGD) or OGD/reperfusion (OGD/R). The KCNQ/M-channel opener, retigabine (RTG), suppressed the overactivation of postsynaptic NMDARs induced by OGD and then NO transient; RTG also decreased OGD-induced neuronal death measured with MTT assay, suggesting the beneficial role of KCNQ/M-channels for the neurons exposed to ischemic insults. However, when the neurons exposed to the subsequent reperfusion, KCNQ/M-channels played a differential role from its protective effect. OGD/R increased presynaptic glutamatergic release, which was further augmented by RTG or decreased by KCNQ/M-channel blocker, XE991. Reactive oxygen species (ROS) were produced partly in a NO-dependent manner. In addition, XE991 decreased neuronal injuries upon reperfusion measured with DCF and PI staining. Meanwhile, the addition of RTG upon OGD or XE991 upon reperfusion can reverse OGD or OGD/R-reduced mitochondrial membrane potential. Our present study indicates the dual role of KCNQ/M-channels in OGD and OGD/R, which will decide the fate of neurons. Provided that activation of KCNQ/M-channels has differential effects on neuronal injuries during OGD or OGD/R, we propose that therapy targeting KCNQ/M-channels may be effective for ischemic injuries but the proper timing is so crucial for the corresponding treatment.

Modified Huangqi Chifeng decoction inhibits excessive autophagy to protect against Doxorubicin-induced nephrotic syndrome in rats via the PI3K/mTOR signaling pathway

The aim of the present study was to investigate whether modified Huangqi Chifeng decoction (MHCD) could be an effective treatment against Doxorubicin-induced nephrosis in rats and whether it regulates autophagy via the phosphoinositide-3 kinase/mammalian target of rapamycin (PI3K/mTOR) signaling pathway. A total of 40 male Sprague-Dawley rats were randomly divided into blank, model, telmisartan and MHCD groups. The rat model of nephrosis was induced by intragastric administration of Doxorubicin for 8 weeks. Rats were housed in metabolic cages and urine was collected once every 2 weeks to measure 24-h protein levels. Blood samples were obtained from the abdominal aorta and levels of albumin (ALB), total cholesterol (TCH), triacylglyceride (TG) and serum creatinine (Scr) were assessed. Renal pathological changes were examined using hematoxylin-eosin, Masson's trichome and periodic acid-Schiff staining. Podocytes and autophagosomes were observed using an electron microscope. The expression and distribution of microtubule-associated proteins 1A/1B light chain 3B (LC3), LC3-I, LC3-II, beclin-1, PI3K and mTOR were determined using immunohistochemistry and western blotting. At weeks 6 and 8, 24-h proteinuria significantly decreased in the MHCD group compared with the model group (P<0.05). Compared with the model group, the MHCD group exhibited significantly reduced levels of TG, TCH and Scr, as well as significantly increased ALB levels (P<0.05). MHCD was demonstrated to prevent glomerular and podocyte injury. The number of autophagosomes was significantly decreased and the expression of beclin-1, LC3, LC3-I and LC3-II was inhibited following MHCD treatment compared with the model group (P<0.05). MHCD treatment significantly increased the expression of PI3K and mTOR in Doxorubicin nephrotic rats compared with the model group (P<0.05). In conclusion, MHCD was demonstrated to ameliorate proteinuria and protect against glomerular and podocyte injury by inhibiting excessive autophagy via the PI3K/mTOR signaling pathway.

The differences between GluN2A and GluN2B signaling in the brain

The N-methyl-d-aspartate (NMDA) receptor, a typical ionotropic glutamate receptor, is a crucial protein for maintaining brain function. GluN2A and GluN2B are the main types of NMDA receptor subunit in the adult forebrain. Studies have demonstrated that they play different roles in a number of pathophysiological processes. Although the underlying mechanism for this has not been clarified, the most fundamental reason may be the differences between the signaling pathways associated with GluN2A and GluN2B. With the aim of elucidating the reasons behind the diverse roles of these two subunits, we described the signaling differences between GluN2A and GluN2B from the aspects of C-terminus-associated molecules, effects on typical downstream signaling proteins, and metabotropic signaling. Because there are several factors interfering with the determination of subunit-specific signaling, there is still a long way to go toward clarifying the signaling differences between these two subunits. Developing better pharmacology tools, such as highly selective antagonists for triheteromeric GluN2A- and GluN2B-containing NMDA receptors, and establishing new molecular biological methods, for example, engineering photoswitchable NMDA receptors, may be useful for clarifying the signaling differences between GluN2A and GluN2B.

Consumption of pomegranates improves synaptic function in a transgenic mice model of Alzheimer's disease

Alzheimer's Disease (AD) is a progressive neurodegenerative disorder characterized by extracellular plaques containing abnormal Amyloid Beta (Aβ) aggregates, intracellular neurofibrillary tangles containing hyperphosphorylated tau protein, microglia-dominated neuroinflammation, and impairments in synaptic plasticity underlying cognitive deficits. Therapeutic strategies for the treatment of AD are currently limited. In this study, we investigated the effects of dietary supplementation of 4% pomegranate extract to a standard chow diet on neuroinflammation, and synaptic plasticity in APPsw/Tg2576 mice brain. Treatment with a custom mixed diet (pellets) containing 4% pomegranate for 15 months ameliorated the loss of synaptic structure proteins, namely PSD-95, Munc18-1, and SNAP25, synaptophysin, phosphorylation of Calcium/Calmodulin Dependent Protein Kinase IIα (p-CaMKIIα/ CaMKIIα), and phosphorylation of Cyclic AMP-Response Element Binding Protein (pCREB/CREB), inhibited neuroinflammatory activity, and enhanced autophagy, and activation of the phophoinositide-3-kinase-Akt-mammalian target of rapamycin signaling pathway. These neuroprotective effects were associated with reduced β-site cleavage of Amyloid Precursor Protein in APPsw/Tg2576 mice. Therefore, long-term supplementation with pomegranates can attenuate AD pathology by reducing inflammation, and altering APP-dependent processes.

Microglia activation contributes to quinolinic acid-induced neuronal excitotoxicity through TNF-α

It has been reported that activation of NF-κB is involved in excitotoxicity; however, it is not fully understood how NF-κB contributes to excitotoxicity. The aim of this study is to investigate if NF-κB contributes to quinolinic acid (QA)-mediated excitotoxicity through activation of microglia. In the cultured primary cortical neurons and microglia BV-2 cells, the effects of QA on cell survival, NF-κB expression and cytokines production were investigated. The effects of BV-2-conditioned medium (BCM) on primary cortical neurons were examined. The effects of pyrrolidine dithiocarbamate (PDTC), an inhibitor of NF-κB, and minocycline (MC), an inhibitor of microglia activation, on QA-induced excitotoxicity were assessed. QA-induced NF-κB activation and TNF-α secretion, and the roles of TNF-α in excitotoxicity were studied. QA at the concentration below 1 mM had no apparent toxic effects on cultured primary neurons or BV-2 cells. However, addition of QA-primed BCM to primary neurons did aggravate QA-induced excitotoxicity. The exacerbation of QA-induced excitotoxicity by BCM was partially ameliorated by inhibiting NF-κB and microglia activation. QA induced activation of NF-κB and upregulation of TNF-α in BV-2 cells. Addition of recombinant TNF-α mimicked QA-induced excitotoxic effects on neurons, and neutralizing TNF-α with specific antibodies partially abolished exacerbation of QA-induced excitotoxicity by BCM. These studies suggested that QA activated microglia and upregulated TNF-α through NF-κB pathway in microglia. The microglia-mediated inflammatory pathway contributed, at least in part, to QA-induced excitotoxicity.

Neuregulin 1 Reduces Motoneuron Cell Death and Promotes Neurite Growth in an in Vitro Model of Motoneuron Degeneration

Amyotrophic Lateral Sclerosis (ALS) is a devastating neurodegenerative disorder with no effective treatment currently available. Although the mechanisms of motoneuron (MN) death are still unclear, glutamate excitotoxicity and neuroinflammatory reaction are two main features in the neurodegenerative process of ALS. Neuregulin 1 (NRG1) is a trophic factor highly expressed in MNs and neuromuscular junctions. Several recent evidences suggest that NRG1 and their ErbB receptors are involved in ALS. However, further knowledge is still needed to clarify the role of the NRG1-ErbB pathway on MN survival. In this study we used an in vitro model of spinal cord organotypic cultures (SCOCs) subject to chronic excitotoxicity caused by DL-threo-β-hydroxyaspartic acid (THA) to characterize the effect of NRG1 on MN survival. Our results show that addition of recombinant human NRG1 (rhNRG1) to the medium significantly increased MN survival through the activation of ErbB receptors which was ablated with lapatinib (LP), an ErbB inhibitor, and reduced microglial reactivity overcoming the excitotoxicity effects. rhNRG1 activated the pro-survival PI3K/AKT pathway and restored the autophagic flux in the spinal cord culture. Moreover, addition of rhNRG1 to the medium promoted motor and sensory neurite outgrowth. These findings indicate that increasing NRG1 at the spinal cord is an interesting approach for promoting MN protection and regeneration.

Gastrodin protects myocardial cells against hypoxia/reoxygenation injury in neonatal rats by inhibiting cell autophagy through the activation of mTOR signals in PI3K-Akt pathway

Objectives

This study aimed to investigate the protective effect of gastrodin (GAS) on myocardial cells with hypoxia/reoxygenation (H/R) injury in neonatal rats and explore the underlying mechanism.

Methods

Myocardial cells were extracted from neonatal rats and divided into six groups: control, H/R, H/R + Low-Concentration GAS, H/R + Middle-Concentration GAS, H/R + High-Concentration GAS and H/R + High-Concentration GAS + AKT Inhibitor groups. After 48-h treatment, cell viability, autophagosome quantity and the expression levels of LC3-II, p62, Akt, pAkt, mammalian target of rapamycin (mTOR) and uncoordinated 51-like kinase 1 (ULK1) in myocardial cells were made comparisons among each group.

Key findings

Gastrodin improved the proliferation activity of myocardial cells under H/R injury in a dose-dependent manner and inhibited the level of cell autophagy. However, when AKT inhibitor was added, the effect of GAS was partly inhibited (P &lt; 0.05). Gene and protein expressions showed that GAS made no significant effect on the expression quantity of Akt and mTOR genes (P &gt; 0.05) but could significantly promote the phosphorylation of Akt and mTOR (P &lt; 0.05). GAS had significant inhibiting effect on the expression of ULK1 (P &lt; 0.05).

Conclusions

Gastrodin could protect against H/R injury of myocardial cells in neonatal rats by reducing the level of autophagy through the activation of mTOR signals in PI3K-Akt pathway.

Protective Effects of Sodium (±)-5-Bromo-2-(α-Hydroxypentyl) Benzoate in a Rodent Model of Global Cerebral Ischemia

The aim of the current study was to explore the protective effects of sodium (±)-5-bromo-2-(α-hydroxypentyl) benzoate (brand name: brozopine, BZP) in a rat model of global cerebral ischemia. The rat model was established using a modified Winocur's method; close postoperative observation was conducted at all times. Neurological function was detected through prehensile traction and beam-walking test. BZP reduced mortality and prolonged the survival time of rats with global cerebral ischemia, within 24 h. There was a decreased survival rate (60%) in the Model group, while the survival rate of the BZP (3 and 12 mg/kg) remarkably increased the survival rate (to 80 and 90%, respectively), in a dose-dependent manner. Compared with the Model group (survival time: 18.50 h), the administration of BZP (0.75, 3, and 12 mg/kg) prolonged the survival time (to 20.38, 21.85, and 23.90 h, respectively), particularly in BZP 12 mg/kg group (P < 0.05). Additionally, the BZP (12 mg/kg) group exhibited an improvement in their motor function (P < 0.05). The BZP groups (0.75, 3, and 12 mg/kg) displayed significantly reduced necrosis and the percentage of apoptotic cells (P < 0.05 and P < 0.01, respectively). Compared with Model group, BZP (0.75, 3, and 12 mg/kg) increased the NeuN optical density values (P < 0.01). Rats with global ischemia had a high expression of Cyt-c, caspase-3, and the Bax/Bcl-2 ratio compared with sham group (P < 0.01). BZP (0.75, 3, and 12 mg/kg), however, reduced the expression of Cyt-c, caspase-3, and the Bax/Bcl-2 ratio, in a dose-dependent manner (P < 0.01). There was low expression of p-Akt and PI3K in Model group, compared with the sham group (P < 0.01). Meanwhile, BZP (0.75, 3, and 12 mg/kg) increased the expression of p-Akt and PI3K in a dose-dependent manner (P < 0.01). We also found the expression of Cyt-c, caspase-3, Bax/Bcl-2 ratio, PI3K, p-Akt, and comprehensive score were directly related. In conclusion, BZP had therapeutic potential and prevented stroke in rat model of global cerebral ischemia. The underlying mechanisms may be related to the inhibition of apoptosis and activation of the survival-signaling-pathway.

Insulin-Like Growth Factors in the Pathogenesis of Neurological Diseases in Children

Insulin-like growth factors play a key role for neuronal growth, differentiation, the survival of neurons and synaptic formation. The action of IGF-1 is most pronounced in the developing brain. In this paper we will try to give an answer to the following questions: Why are studies in children important? What clinical studies in neonatal asphyxia, infantile spasms, progressive encephalopathy-hypsarrhythmia-optical atrophy (PEHO) syndrome, infantile ceroid lipofuscinosis (INCL), autistic spectrum disorders (ASD) and subacute sclerosing encephalopathy (SSPE) have been carried out? What are IGF-based therapeutic strategies? What are the therapeutic approaches? We conclude that there are now great hopes for the therapeutic use of IGF-1 for some neurological disorders (particularly ASD).

RNF146 Inhibits Excessive Autophagy by Modulating the Wnt-β-Catenin Pathway in Glutamate Excitotoxicity Injury

Glutamate induced excitotoxicity is common in diverse neurological disorders. RNF146 as an E3 ubiquitin ligase protects neurons against excitotoxicity via interfering with Poly (ADP-ribose) (PAR) polymer-induced cell death (parthanatos). However, the neuroprotective role of RNF146 has not been fully understood. We aimed to investigate the role of RNF146 in modulating autophagy in HT22 cells under glutamate excitotoxicity injury. Here we found that induction of RNF146 decreased the cellular damage and excitotoxicity induced by glutamate. RNF146 also suppressed the excessive autophagy, which is detrimental to HT22 cells survival, induced by glutamate or rapamycin treatment. In addition, we find that Wnt/β-catenin was a negative regulation factor for autophagy in glutamate excitotoxicity. Over-expression of RNF146 promoted Wnt/β-catenin signaling, which was related to destabilization of β-catenin destruction complex. These results indicated that RNF146 acted as a neuroprotective agent against glutamate-induced excitatory damage, and this neuroprotection might be at least partly dependent on the inhibition of excessive autophagy by regulating Wnt/β-catenin signaling.