EGB1212 Post-treatment Ameliorates Hippocampal CA1 Neuronal Death and Memory Impairment Induced by Transient Global Cerebral Ischemia/Reperfusion

TXNIP/NLRP3 aggravates global cerebral ischemia-reperfusion injury-induced cognitive decline in mice

Global cerebral ischemia/reperfusion (GCI/R) injury poses a risk for cognitive decline, with neuroinflammation considered pivotal in this process. This study aimed to unravel the molecular mechanisms underlying GCI/R injury and propose a potential therapeutic strategy for associated cognitive deficits. Utilizing bioinformatics analysis of a public microarray profile (GSE30655 and GSE80681) in cerebral ischemic mice, it was observed that neuroinflammation emerged as a significant gene ontology item, with an increase in the expression of thioredoxin-interacting protein (TXNIP) and NLRP3 genes. Experimental models involving bilateral occlusion of the common carotid arteries in mice revealed that GCI/R induced cognitive impairment, along with a time-dependent increase in TXNIP and NLRP3 levels. Notably, TXNIP knockdown alleviated cognitive dysfunction in mice. Furthermore, the introduction of adeno-associated virus injection with TXNIP knockdown reduced the number of activated microglia, apoptosis neurons, and levels of oxidative stress and inflammatory cytokines in the hippocampus. Collectively, these findings underscore the significance of TXNIP/NLRP3 in the hippocampus in exacerbating cognitive decline due to GCI/R injury, suggesting that TXNIP knockdown holds promise as a therapeutic strategy.

Global cerebral ischemia in adolescent male Long Evans rats: Effects of vanillic acid supplementation on stress response, emotionality, and visuospatial memory

The developmental period is critical in delineating plastic response to internal and external events. However, neurobehavioural effects of global cerebral ischemia (GCI) in the maturing brain remain largely unknown. This study characterised the effects of GCI experienced at puberty on adulthood (1) hippocampus CA1 neuronal damage, (2) cognitive and emotional impairments, and (3) glucocorticoid receptor (GR) expression. Effects of adolescent exposure to the phenol vanillic acid (VA) on post-ischemic outcomes were also determined. Male Long Evans rats (n = 35) were supplemented for 21 consecutive days (postnatal days 33-53) with VA (91 mg/kg) or nut paste vehicle (control) prior to a 10-min GCI or sham surgery. As adults, rats were tested in the Open Field Test (OFT), Elevated-Plus Maze (EPM), and Barnes Maze (BM). GR expression was determined in the basolateral amygdala (BLA), CA1, and paraventricular nucleus (PVN), and brain injury assessed via CA1 neuronal density. Adolescent GCI exposure induced extensive hippocampal CA1 injury, which was not prevented by VA supplementation. Behaviourally, GCI increased EPM exploration while having no impact on spatial memory. VA intake increased OFT peripheral exploration. Notably, while no delayed changes in CA1 and PVN GR immunoreactivity were noted, both treatments separately increased BLA GR expression when compared with sham-nut paste rats. Age at GCI occurrence plays a critical role on post-ischemic impairments. The observation of minimal functional impairments despite important CA1 neuronal damage supports use of compensatory mechanisms. Our findings also show daily VA supplementation during adolescence to have no protective effects on post-ischemic outcomes, contrasting adult intake.

Anti-apoptotic effect of silymarin-loaded chitosan nanoparticles on hippocampal caspase-3 and Bcl-2 expression following cerebral ischemia/reperfusion injury

BACKGROUND

Cerebral ischemia/reperfusion (I/R) causes memory and learning impairments and apoptosis in the hippocampus. The aim of present study aimed to investigate the anti-apoptotic effects of silymarin-loaded chitosan nanoparticles (SM-CS-NPs) on the expression of Bcl-2 and Caspase-3 genes in hippocampal neurons after I/R injury.

MATERIAL AND METHODS

SM and SM-CS-NPs were orally administered (15 mg/kg) for 14 days, and then cerebral I/R injury was induced by the bilateral common carotid artery occlusion (BCCAO). One day after I/R induction, memory and learning impairments and various biochemical estimations were assessed.

RESULTS

Our results indicated that SM-CS-NPs improved I/R-induced memory and learning impairments and oxidative damage in the hippocampal region. The qRT-PCR analysis indicated that SM-CS-NPs pretreatment inhibited I/R-induced neuronal apoptosis by increasing the expression of Bcl-2 and decreasing the expression of Caspase-3 in the hippocampus.

CONCLUSION

These findings suggest that SM-CS-NPs exert neuroprotective effects, and the neuroprotection is likely to be associated with the regulation of Bcl-2 and Caspase-3, leading to inhibition of apoptotic cell death in hippocampal neurons.

Dysregulation of metabolic flexibility: The impact of mTOR on autophagy in neurodegenerative disease

Non-communicable diseases (NCDs) that involve neurodegenerative disorders and metabolic disease impact over 400 million individuals globally. Interestingly, metabolic disorders, such as diabetes mellitus, are significant risk factors for the development of neurodegenerative diseases. Given that current therapies for these NCDs address symptomatic care, new avenues of discovery are required to offer treatments that affect disease progression. Innovative strategies that fill this void involve the mechanistic target of rapamycin (mTOR) and its associated pathways of mTOR complex 1 (mTORC1), mTOR complex 2 (mTORC2), AMP activated protein kinase (AMPK), trophic factors that include erythropoietin (EPO), and the programmed cell death pathways of autophagy and apoptosis. These pathways are intriguing in their potential to provide effective care for metabolic and neurodegenerative disorders. Yet, future work is necessary to fully comprehend the entire breadth of the mTOR pathways that can effectively and safely translate treatments to clinical medicine without the development of unexpected clinical disabilities.

New Insights for nicotinamide: Metabolic disease, autophagy, and mTOR

Metabolic disorders, such as diabetes mellitus (DM), are increasingly becoming significant risk factors for the health of the global population and consume substantial portions of the gross domestic product of all nations. Although conventional therapies that include early diagnosis, nutritional modification of diet, and pharmacological treatments may limit disease progression, tight serum glucose control cannot prevent the onset of future disease complications. With these concerns, novel strategies for the treatment of metabolic disorders that involve the vitamin nicotinamide, the mechanistic target of rapamycin (mTOR), mTOR Complex 1 (mTORC1), mTOR Complex 2 (mTORC2), AMP activated protein kinase (AMPK), and the cellular pathways of autophagy and apoptosis offer exceptional promise to provide new avenues of treatment. Oversight of these pathways can promote cellular energy homeostasis, maintain mitochondrial function, improve glucose utilization, and preserve pancreatic beta-cell function. Yet, the interplay among mTOR, AMPK, and autophagy pathways can be complex and affect desired clinical outcomes, necessitating further investigations to provide efficacious treatment strategies for metabolic dysfunction and DM.

Shuxuening injection facilitates neurofunctional recovery via down-regulation of G-CSF-mediated granulocyte adhesion and diapedesis pathway in a subacute stroke mouse model

Post-stroke neural damage is a serious health concern which does not yet have an effective treatment. We have shown previously that Shuxuening injection (SXNI), a Ginkgo biloba extract-based natural medicine, protects brain after an acute ischemic stroke, but its efficacy for post-stroke recovery is not known. This study was to investigate whether SXNI can improve the prognosis of stroke at a subacute phase. Mice with cerebral ischemia-reperfusion injury (CIRI) were established by middle cerebral artery occlusion (MCAO), and drugs or saline were injected by the tail vein every 12 h after reperfusion. The therapeutic effect of SXNI was evaluated by survival rate, modified neurologic severity scores (mNSS), open-field test, locomotive gait patterns, cerebral infarction volume, brain edema and histopathological changes. Subsequently, a combined method of RNA-seq and Ingenuity® Pathway Analysis (IPA) was performed to identify key targets and pathways of SXNI facilitating the prognosis of stroke in mouse brain. The results of the transcriptome analysis were verified by real time reverse transcription-polymerase chain reaction (RT-PCR), enzyme-linked immunosorbent assay (ELISA), western blot (WB) and immunohistochemistry (IHC). The experimental results showed that in the new subacute stroke model, SXNI markedly improves the survival rate, neurological and motor functions and histopathological changes, and significantly reduces cerebral infarction and edema volume. RNA-seq analysis of subacute stroke mice with or without SXNI (3 mL/kg) indicated 963 differentially expressed genes (DEGs) with a fold change ≥ 1.5 and a P-value ≤ 0.01. IPA analysis of DEGs showed that granulocyte adhesion and diapedesis ranked first in the pathway ranking, and the most critical gene regulated by SXNI was G-csf. Simultaneously, RT-PCR, ELISA, WB and IHC results demonstrated that SXNI not only obviously reduced the mRNA expression levels of key genes G-csf, Sele and Mac-1 in this pathway, but also significantly decreased the protein expression levels of G-CSF in serum and E-selectin and MAC-1 in brain tissues. In summary, our research suggested that SXNI can exert a remarkable neurofunctional therapeutic effect on stroke mice via down-regulating G-CSF to inhibit granulocyte adhesion and diapedesis. This study provides experimental evidence that SXNI may fulfill the need for stroke medicine targeting specifically at the recovery stage.

Nicotinamide: Oversight of Metabolic Dysfunction Through SIRT1, mTOR, and Clock Genes

Metabolic disorders that include diabetes mellitus present significant challenges for maintaining the welfare of the global population. Metabolic diseases impact all systems of the body and despite current therapies that offer some protection through tight serum glucose control, ultimately such treatments cannot block the progression of disability and death realized with metabolic disorders. As a result, novel therapeutic avenues are critical for further development to address these concerns. An innovative strategy involves the vitamin nicotinamide and the pathways associated with the silent mating type information regulation 2 homolog 1 (Saccharomyces cerevisiae) (SIRT1), the mechanistic target of rapamycin (mTOR), mTOR Complex 1 (mTORC1), mTOR Complex 2 (mTORC2), AMP activated protein kinase (AMPK), and clock genes. Nicotinamide maintains an intimate relationship with these pathways to oversee metabolic disease and improve glucose utilization, limit mitochondrial dysfunction, block oxidative stress, potentially function as antiviral therapy, and foster cellular survival through mechanisms involving autophagy. However, the pathways of nicotinamide, SIRT1, mTOR, AMPK, and clock genes are complex and involve feedback pathways as well as trophic factors such as erythropoietin that require a careful balance to ensure metabolic homeostasis. Future work is warranted to gain additional insight into these vital pathways that can oversee both normal metabolic physiology and metabolic disease.

The neuroprotective mechanisms of ginkgolides and bilobalide in cerebral ischemic injury: a literature review

The incidence and mortality of strokes have increased over the past three decades in China. Ischemic strokes can cause a sequence of detrimental events in patients, including increased permeability and dysfunction of the blood-brain barrier, brain edema, metabolic disturbance, endoplasmic reticulum stress, autophagy, oxidative stress, inflammation, neuron death and apoptosis, and cognitive impairment. Thrombolysis using recombinant tissue plasminogen activator (rtPA) and mechanical embolectomy with a retrievable stent are two recognized strategies to achieve reperfusion after a stroke. Nevertheless, rtPA has a narrow therapeutic timeframe, and mechanical embolectomy has limited rates of good neurological outcomes. EGb761 is a standardized and extensively studied extract of Ginkgo biloba leaves. The ginkgolides and bilobalide that constitute a critical part of EGb761 have demonstrated protective properties towards cerebral injury. Ginkgolides include Ginkgolide A (GA), Ginkgolide B (GB), Ginkgolide C (GC), Ginkgolide J (GJ), Ginkgolide K (GK), Ginkgolide L (GL), and Ginkgolide M (GM). This review seeks to elucidate the neuroprotective effects and mechanisms of ginkgolides, especially GA and GB, and bilobalide in cerebral injury following ischemic strokes.

Hyperbaric oxygen alleviated cognitive impairments in mice induced by repeated cerebral ischemia-reperfusion injury via inhibition of autophagy

AIMS

In this study, we investigate the effect and underlying mechanism of hyperbaric oxygen (HBO) treatment on a model of repeated cerebral ischemia-reperfusion injury (IR).

MAIN METHODS

Eighty rats were randomly separated into sham, vehicle, hyperbaric air (HBA; 0.25 MPa, 60 min), and HBO (0.25 MPa, 60 min) groups. Repeated cerebral IR was induced by ligating the right and left bilateral common carotid arteries for 10 min and then allowing reperfusion for 10 min. This pattern was repeated three times. The neuroprotective effects of HBO were assessed by animal behavior, neuron morphology, inflammatory markers, intracellular calcium ion content, and autophagy-related protein and gene expression.

KEY FINDINGS

Our result showed that HBO improved learning and memory in the navigation trail and probe trail of the Morris water maze, and these findings were supported by the observation data from 2,3,5-Triphenyltet-razolium chloride staining, Nissl staining, and electron microscopic. Importantly, we found that HBO reduced excessive autophagy in the prefrontal cortex, which was evidenced by activating of the mammalian target of the rapamycin (mTOR) and 4E-BP1, as well as suppression of LC3II and ATG5. Moreover, HBO significantly inhibited the cerebral IR-induced inflammatory reaction. Furthermore, HBO treatment modulated autophagy pathway-related factors, including producing a decrease in the intracellular calcium ion concentration and p53 level; meanwhile, the levels of BDNF and p-Akt were increased.

SIGNIFICANCE

Our results indicated that HBO protected against IR-induced neuron injury by attenuating autophagy, inflammation, and calcium overload. These results provide a new mechanism and laboratory evidence for clinical treatment of VD.

Standardized Ginkgo biloba extract EGb 761® attenuates early brain injury following subarachnoid hemorrhage via suppressing neuronal apoptosis through the activation of Akt signaling

BACKGROUND

Early brain injury (EBI) plays a critical role in determining the outcome of subarachnoid hemorrhage (SAH). The present study was designed to investigate the role of EGb 761, a standardized extract of Ginkgo biloba, in SAH-induced EBI and to explore its potential mechanism of action.

METHOD

A rat SAH model was established by the endovascular perforation process. Doses of 10, 50 and 100 mg/kg EGb 761 were injected intraperitoneally 2 h after SAH was induced. Mortality, SAH grade, neurological score and brain water content were measured 24 h after SAH was induced. A Western blot assay was performed to assess the expression of the apoptosis-related proteins Bax, Bcl-2, cleaved caspase-3, Akt and phosphorylated Akt (p-Akt). Terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) and neuronal nuclei (NeuN) double immunofluorescence staining were used to detect apoptotic neurons.

RESULTS

Animals suffered from serious neurological deficits and increased brain water content after induction of SAH. Rats treated with EGb 761 experienced dose-dependent attenuation of neurological dysfunction and decreased brain water content. In addition, EGb 761 significantly activated Akt signaling accompanied by increased Bcl-2 levels and decreased expression of Bax and cleaved caspase-3. Moreover, EGb 761 decreased the number of TUNEL/NeuN-positive cells in a dose-dependent manner. However, all the beneficial effects of EGb 761 for SAH were abolished by the Akt inhibitor MK2206.

CONCLUSION

Our results indicated that EGb 761 could ameliorate SAH-induced EBI and that the neuroprotective effects of EGb 761 against SAH were exerted via suppression of neuronal apoptosis through activation of the Akt pathway.

The mechanistic target of rapamycin (mTOR) and the silent mating-type information regulation 2 homolog 1 (SIRT1): oversight for neurodegenerative disorders

As a result of the advancing age of the global population and the progressive increase in lifespan, neurodegenerative disorders continue to increase in incidence throughout the world. New strategies for neurodegenerative disorders involve the novel pathways of the mechanistic target of rapamycin (mTOR) and the silent mating-type information regulation 2 homolog 1 (Saccharomyces cerevisiae) (SIRT1) that can modulate pathways of apoptosis and autophagy. The pathways of mTOR and SIRT1 are closely integrated. mTOR forms the complexes mTOR Complex 1 and mTOR Complex 2 and can impact multiple neurodegenerative disorders that include Alzheimer's disease, Huntington's disease, and Parkinson's disease. SIRT1 can control stem cell proliferation, block neuronal injury through limiting programmed cell death, drive vascular cell survival, and control clinical disorders that include dementia and retinopathy. It is important to recognize that oversight of programmed cell death by mTOR and SIRT1 requires a fine degree of precision to prevent the progression of neurodegenerative disorders. Additional investigations and insights into these pathways should offer effective and safe treatments for neurodegenerative disorders.

Erythropoietin and mTOR: A "One-Two Punch" for Aging-Related Disorders Accompanied by Enhanced Life Expectancy

Life expectancy continues to increase throughout the world, but is accompanied by a rise in the incidence of non-communicable diseases. As a result, the benefits of an increased lifespan can be limited by aging-related disorders that necessitate new directives for the development of effective and safe treatment modalities. With this objective, the mechanistic target of rapamycin (mTOR), a 289-kDa serine/threonine protein, and its related pathways of mTOR Complex 1 (mTORC1), mTOR Complex 2 (mTORC2), proline rich Akt substrate 40 kDa (PRAS40), AMP activated protein kinase (AMPK), Wnt signaling, and silent mating type information regulation 2 homolog 1 (Saccharomyces cerevisiae) (SIRT1), have generated significant excitement for furthering novel therapies applicable to multiple systems of the body. Yet, the biological and clinical outcome of these pathways can be complex especially with oversight of cell death mechanisms that involve apoptosis and autophagy. Growth factors, and in particular erythropoietin (EPO), are one avenue under consideration to implement control over cell death pathways since EPO can offer potential treatment for multiple disease entities and is intimately dependent upon mTOR signaling. In experimental and clinical studies, EPO appears to have significant efficacy in treating several disorders including those involving the developing brain. However, in mature populations that are affected by aging-related disorders, the direction for the use of EPO to treat clinical disease is less clear that may be dependent upon a number of factors including the understanding of mTOR signaling. Continued focus upon the regulatory elements that control EPO and mTOR signaling could generate critical insights for targeting a broad range of clinical maladies.

Targeting molecules to medicine with mTOR, autophagy and neurodegenerative disorders

Neurodegenerative disorders are significantly increasing in incidence as the age of the global population continues to climb with improved life expectancy. At present, more than 30 million individuals throughout the world are impacted by acute and chronic neurodegenerative disorders with limited treatment strategies. The mechanistic target of rapamycin (mTOR), also known as the mammalian target of rapamycin, is a 289 kDa serine/threonine protein kinase that offers exciting possibilities for novel treatment strategies for a host of neurodegenerative diseases that include Alzheimer's disease, Parkinson's disease, Huntington's disease, epilepsy, stroke and trauma. mTOR governs the programmed cell death pathways of apoptosis and autophagy that can determine neuronal stem cell development, precursor cell differentiation, cell senescence, cell survival and ultimate cell fate. Coupled to the cellular biology of mTOR are a number of considerations for the development of novel treatments involving the fine control of mTOR signalling, tumourigenesis, complexity of the apoptosis and autophagy relationship, functional outcome in the nervous system, and the intimately linked pathways of growth factors, phosphoinositide 3-kinase (PI 3-K), protein kinase B (Akt), AMP activated protein kinase (AMPK), silent mating type information regulation two homologue one (Saccharomyces cerevisiae) (SIRT1) and others. Effective clinical translation of the cellular signalling mechanisms of mTOR offers provocative avenues for new drug development in the nervous system tempered only by the need to elucidate further the intricacies of the mTOR pathway.

Dexmedetomidine preconditioning attenuates global cerebral ischemic injury following asphyxial cardiac arrest

BACKGROUND/AIMS

To investigate the protection effect of dexmedetomidine preconditioning on global cerebral ischemic injury following asphyxial cardiac arrest (CA) in rats.

METHODS

Seventy-two rats were randomly assigned into three groups, sham group (no asphyxia), control group (asphyxia only), and dexmedetomidine preconditioned group (asphyxia + dexmedetomidine). Dexmedetomidine was administered 5 minutes before an 8 min of asphyxia. Rats were resuscitated by a standardized method. Blood O(2) and CO(2) partial pressures were, pH, base excess (BE), and blood glucose concentration measured before asphyxial CA and 1 h after resuscitation. Neurological deficit score (NDS) was measured at 12, 24, 48, and 72 h after CA. Histopathologic changes in the hippocampal region were observed by H&E staining and histopathologic damage score. Ultrastructural morphology was observed by transmission electron microscopy. HIF-1 and VEGF expression were measured by immunostaining of serial sections obtained from brain tissue.

RESULTS

Asphyxial CA -induced global cerebral ischemic decreased PaO(2), pH, BE and increased PaCO(2), blood glucose. Dexmedetomidine preconditioning improved neurologic outcome, which was associated with reduction in histopathologic injury measured by H&E staining, the histopathologic damage score and electron microscopy. Dexmedetomidine preconditioning also elevated HIF-1α and VEGF expression after global cerebral ischemia following asphyxial CA.

CONCLUSION

Dexmedetomidine preconditioning protected against cerebral ischemic injury and was associated with upregulation of HIF-1α and VEGF expression.

Long-term treatment with Ginkgo biloba extract EGb 761 improves symptoms and pathology in a transgenic mouse model of Alzheimer's disease

Alzheimer's disease (AD) is a neurodegenerative disease characterized by extracellular deposits of amyloid β peptide (Aβ) and microglia-dominated neuroinflammation. The therapeutic options for AD are currently limited. In this study, we investigated the antiinflammatory effects and the underlying molecular mechanisms of Ginkgo biloba extract EGb 761 when administered to TgCRND8 AD mice, which overexpress human Alzheimer's amyloid precursor protein (APP) specifically in neurons. We gave APP-transgenic mice EGb 761 as a dietary supplement for 2 or 5months. Plasma concentrations of EGb 761 components in mice were in the same range as such concentrations in humans taking EGb 761 at the recommended dose (240mg daily). Treatment with EGb 761 for 5months significantly improved the cognitive function of the mice as measured by the Barnes Maze test. It also attenuated the loss of synaptic structure proteins, such as PSD-95, Munc18-1, and SNAP25. Treatment with EGb 761 for 5months inhibited microglial inflammatory activation in the brain. The effects of treatment with EGb 761 for 2months were weak and not statistically significant. Moreover, EGb 761 activated autophagy in microglia. Treatment with EGb 761 decreased Aβ-induced microglial secretion of TNF-α and IL-1β and activation of caspase-1, both of which were abolished by the inhibition of autophagy. Treatment with EGb 761 also reduced the concentrations of NLRP3 protein that colocalized with LC3-positive autophagosomes or autolysosomes in microglia. Additionally, long-term treatment with EGb 761 may reduce cerebral Aβ pathology by inhibiting β-secretase activity and Aβ aggregation. Therefore, long-term treatment with G. biloba extract EGb 761, a clinically available and well-tolerated herbal medication, ameliorates AD pathology by antiinflammatory and Aβ-directed mechanisms.

Ginkgo biloba on focal cerebral ischemia: a systematic review and meta-analysis

Gingko biloba extract (EGB) has been used in traditional medicines for centuries, and although its application to cerebral ischemia has been of great interest in recent years, high quality evidence-based clinical trials have not been carried out. This systematic review and meta-analysis aimed to examine the neuroprotective effect of EGB on focal cerebral ischemia in animal models. A systematic literature search was performed using five databases spanning January 1980-July 2013. The outcome was assessed using the effect size, which was based on infarct size and/or neurological score. A total of 42 studies with 1,232 experimental animals matched our inclusion criteria. The results revealed that EGB improved the effect size by 34% compared to the control group. The animal species, the method and time to measure outcome, and the route and dosage of EGB administration affected the variability of the effect size. Mechanisms of EGB neuroprotection were reported as anti-apoptotic, anti-oxidative, and anti-inflammatory. In conclusion, EGB exerts a significant protective effect on experimental focal cerebral ischemia. However, possible experimental bias should be taken into account in future clinical studies.

Taking aim at Alzheimer's disease through the mammalian target of rapamycin

A significant portion of the world's population suffers from sporadic Alzheimer's disease (AD) with available present therapies limited to symptomatic care that does not alter disease progression. Over the next decade, advancing age of the global population will dramatically increase the incidence of AD and severely impact health care resources, necessitating novel, safe, and efficacious strategies for AD. The mammalian target of rapamycin (mTOR) and its protein complexes mTOR Complex 1 (mTORC1) and mTOR Complex 2 (mTORC2) offer exciting and unique avenues of intervention for AD through the oversight of programmed cell death pathways of apoptosis, autophagy, and necroptosis. mTOR modulates multi-faceted signal transduction pathways that involve phosphoinositide 3-kinase (PI 3-K), protein kinase B (Akt), hamartin (tuberous sclerosis 1)/ tuberin (tuberous sclerosis 2) (TSC1/TSC2) complex, proline-rich Akt substrate 40 kDa (PRAS40), and p70 ribosomal S6 kinase (p70S6K) and can interface with the neuroprotective pathways of growth factors, sirtuins, wingless, forkhead transcription factors, and glycogen synthase kinase-3β. With the ability of mTOR to broadly impact cellular function, clinical strategies for AD that implement mTOR must achieve parallel objectives of protecting neuronal, vascular, and immune cell survival in conjunction with preserving networks that determine memory and cognitive function.

Citrus medica var. sarcodactylis (Foshou) activates fibroblast growth factor-2 signaling to induce migration of RSC96 Schwann cells

Factors that enhance the intrinsic growth potential of neurons play a major role in the regeneration and repair of adult neurons following an injury. Fibroblast growth factor (FGF-2) is one of the key players in the origin and growth of neuronal and glial cells through autocrine and paracrine signaling. Water extract of Citrus medica var. sarcodactylis (fingered citron, foshou), which is been used effectively as a Chinese herbal medicine, was found to activate the FGF-2 promoter in transgenic luciferase expression models. Foshou treatment on Schwann cells (RSC96) transfected with luciferase reporter plasmid under a FGF-2 promoter was found to induce the FGF-2 promoter and showed enhanced luciferase expression. The FGF-2 expression was accompanied with an increase in the expression of proteins involved in cell migration and cell proliferation in a dose dependent manner. Therefore, foshou potentially enhances nerve regeneration by inducing the Schwann cell proliferation and migration.

Driving neural regeneration through the mammalian target of rapamycin

Neurodegenerative disorders affect more than 30 million individuals throughout the world and lead to significant disability as well as death. These statistics will increase almost exponentially as the lifespan and age of individuals increase globally and individuals become more susceptible to acute disorders such as stroke as well as chronic diseases that involve cognitive loss, Alzheimer's disease, and Parkinson's disease. Current therapies for such disorders are effective only for a small subset of individuals or provide symptomatic relief but do not alter disease progression. One exciting therapeutic approach that may turn the tide for addressing neurodegenerative disorders involves the mammalian target of rapamycin (mTOR). mTOR is a component of the protein complexes mTOR Complex 1 (mTORC1) and mTOR Complex 2 (mTORC2) that are ubiquitous throughout the body and control multiple functions such as gene transcription, metabolism, cell survival, and cell senescence. mTOR through its relationship with phosphoinositide 3-kinase (PI 3-K) and protein kinase B (Akt) and multiple downstream signaling pathways such as p70 ribosomal S6 kinase (p70S6K) and proline rich Akt substrate 40 kDa (PRAS40) promotes neuronal cell regeneration through stem cell renewal and oversees critical pathways such as apoptosis, autophagy, and necroptosis to foster protection against neurodegenerative disorders. Targeting by mTOR of specific pathways that drive long-term potentiation, synaptic plasticity, and β-amyloid toxicity may offer new strategies for disorders such as stroke and Alzheimer's disease. Overall, mTOR is an essential neuroprotective pathway but must be carefully targeted to maximize clinical efficacy and eliminate any clinical toxic side effects.