Rapamycin restores brain vasculature, metabolism, and blood-brain barrier in an inflammaging model

Visualization of Blood-Brain Barrier Disruption in Septic Mice with the New Method Based on in Vivo Imaging Technology

BACKGROUND

Dynamic monitoring of the blood-brain barrier (BBB) functional status in septic mice can help to explore the pathological mechanisms. Therefore, we proposed a new method for monitoring BBB permeability and applied it to the detection of sepsis models.

METHODS

The new method involves the construction of an optical cranial window and in vivo imaging. We performed dynamic monitoring of BBB permeability and cerebral blood flow (CBF) in cecal ligation puncture (CLP) and endotoxemia (lipopolysaccharide [LPS]) mice.

RESULTS

The sensitivity and accuracy of this method were higher than those of Evans blue evaluation. The increase of BBB permeability in the group of CLP mice was relatively mild and correlated with overall survival, and the damage was irreversible. Contrarily, BBB damage in the LPS group was more acute and severe, unrelated to overall survival, but recoverable. The CBF decreased significantly in both model mouse groups 24 h after modeling, but only the CBF proportion decrease in the LPS group was significantly correlated with an increase in BBB permeability. Within 24 h after both models were established, the decrease in blood flow in the digestive organs occurred earlier than in the brain and kidneys, and the decrease in small intestine blood flow in the LPS group progressed faster.

CONCLUSIONS

We have successfully demonstrated the feasibility of our novel method to detect BBB permeability in mice. Our results revealed a significant difference in the BBB permeability change trend between the CLP and LPS model mice when survival curves were consistent. Notably, the CLP-model mice demonstrated a closer resemblance to clinical patients. Our findings suggest that early-stage brain tissue hypoperfusion has a greater impact on BBB function damage in endotoxemia mice, which is related to the faster progression of blood flow redistribution.

Acute neuroendocrine changes after traumatic brain injury

Introduction

Post-traumatic hypopituitarism (PTHP) is a significant, but often neglected consequence of traumatic brain injury (TBI).

Research question

We aimed to provide a comprehensive overview of epidemiology, pathophysiology, clinical features and diagnostic approaches of PTHP.

Materials and methods

MEDLINE, EMBASE, Cochrane Library and Web of Science were searched. 45 articles of human studies evaluating acute endocrine changes following mild, moderate and severe TBI were selected.

Results

Severity of TBI seems to be the most important risk factor of PTHP. Adrenal insufficiency (AI) was present in 10% of TBI patients (prevalence can be as high as 50% after severe TBI), and hypocortisolemia is a predictor of mortality and long-term hypopituitarism. Suppression of the thyroid axis in 2-33% of TBI patients may be an independent predictor of adverse neurological outcome, as well. 9-36% of patients with severe TBI exhibit decreased function of the somatotrophic axis with a divergent effect on the central nervous system. Arginine-Vasopressin (AVP) deficiency is present in 15-51% of patients, associated with increased mortality and unfavorable outcome. Due to shear and injury of the stalk hyperprolactinemia is relatively common (2-50%), but it bears little clinical significance. Sex hormone levels remain within normal values.

Discussion and conclusion

PTHP occurs frequently after TBI, affecting various axis and determining patients' outcome. However, evidence is scarce regarding exact epidemiology, diagnosis, and effective clinical application of hormone substitution. Future studies are needed to identify patients at-risk, determine the optimal timing for endocrine testing, and refine diagnostic and treatment approaches to improve outcome.

Skin-brain axis in Alzheimer's disease - Pathologic, diagnostic, and therapeutic implications: A Hypothetical Review

The dynamic interaction between the brain and the skin is termed the 'skin-brain axis.' Changes in the skin not only reflect conditions in the brain but also exert direct and indirect effects on the brain. Interestingly, the connection between the skin and brain is crucial for understanding aging and neurodegenerative diseases. Several studies have shown an association between Alzheimer's disease (AD) and various skin disorders, such as psoriasis, bullous pemphigoid, and skin cancer. Previous studies have shown a significantly increased risk of new-onset AD in patients with psoriasis. In contrast, skin cancer may reduce the risk of developing AD. Accumulating evidence suggests an interaction between skin disease and AD; however, AD-associated pathological changes mediated by the skin-brain axis are not yet clearly defined. While some studies have reported on the diagnostic implications of the skin-brain axis in AD, few have discussed its potential therapeutic applications. In this review, we address the pathological changes mediated by the skin-brain axis in AD. Furthermore, we summarize (1) the diagnostic implications elucidated through the role of the skin-brain axis in AD and (2) the therapeutic implications for AD based on the skin-brain axis. Our review suggests that a potential therapeutic approach targeting the skin-brain axis will enable significant advances in the treatment of AD.

Personalized, Precision Medicine to Cure Alzheimer's Dementia: Approach #1

The goal of the treatment for Alzheimer's dementia (AD) is the cure of dementia. A literature review revealed 18 major elements causing AD and 29 separate medications that address them. For any individual with AD, one is unlikely to discern which major causal elements produced dementia. Thus, for personalized, precision medicine, all causal elements must be treated so that each individual patient will have her or his causal elements addressed. Twenty-nine drugs cannot concomitantly be administered, so triple combinations of drugs taken from that list are suggested, and each triple combination can be administered sequentially, in any order. Ten combinations given over 13 weeks require 2.5 years, or if given over 26 weeks, they require 5.0 years. Such sequential treatment addresses all 18 elements and should cure dementia. In addition, any comorbid risk factors for AD whose first presence or worsening was within ±1 year of when AD first appeared should receive appropriate, standard treatment together with the sequential combinations. The article outlines a randomized clinical trial that is necessary to assess the safety and efficacy of the proposed treatments; it includes a triple-drug Rx for equipoise. Clinical trials should have durations of both 2.5 and 5.0 years unless the data safety monitoring board (DSMB) determines earlier success or futility since it is uncertain whether three or six months of treatment will be curative in humans, although studies in animals suggest that the briefer duration of treatment might be effective and restore defective neural tracts.

Accelerated Aging Induced by an Unhealthy High-Fat Diet: Initial Evidence for the Role of Nrf2 Deficiency and Impaired Stress Resilience in Cellular Senescence

High-fat diets (HFDs) have pervaded modern dietary habits, characterized by their excessive saturated fat content and low nutritional value. Epidemiological studies have compellingly linked HFD consumption to obesity and the development of type 2 diabetes mellitus. Moreover, the synergistic interplay of HFD, obesity, and diabetes expedites the aging process and prematurely fosters age-related diseases. However, the underlying mechanisms driving these associations remain enigmatic. One of the most conspicuous hallmarks of aging is the accumulation of highly inflammatory senescent cells, with mounting evidence implicating increased cellular senescence in the pathogenesis of age-related diseases. Our hypothesis posits that HFD consumption amplifies senescence burden across multiple organs. To scrutinize this hypothesis, we subjected mice to a 6-month HFD regimen, assessing senescence biomarker expression in the liver, white adipose tissue, and the brain. Aging is intrinsically linked to impaired cellular stress resilience, driven by dysfunction in Nrf2-mediated cytoprotective pathways that safeguard cells against oxidative stress-induced senescence. To ascertain whether Nrf2-mediated pathways shield against senescence induction in response to HFD consumption, we explored senescence burden in a novel model of aging: Nrf2-deficient (Nrf2+/-) mice, emulating the aging phenotype. Our initial findings unveiled significant Nrf2 dysfunction in Nrf2+/- mice, mirroring aging-related alterations. HFD led to substantial obesity, hyperglycemia, and impaired insulin sensitivity in both Nrf2+/- and Nrf2+/+ mice. In control mice, HFD primarily heightened senescence burden in white adipose tissue, evidenced by increased Cdkn2a senescence biomarker expression. In Nrf2+/- mice, HFD elicited a significant surge in senescence burden across the liver, white adipose tissue, and the brain. We postulate that HFD-induced augmentation of senescence burden may be a pivotal contributor to accelerated organismal aging and the premature onset of age-related diseases.

Geroscience and pathology: a new frontier in understanding age-related diseases

Geroscience, a burgeoning discipline at the intersection of aging and disease, aims to unravel the intricate relationship between the aging process and pathogenesis of age-related diseases. This paper explores the pivotal role played by geroscience in reshaping our understanding of pathology, with a particular focus on age-related diseases. These diseases, spanning cardiovascular and cerebrovascular disorders, malignancies, and neurodegenerative conditions, significantly contribute to the morbidity and mortality of older individuals. We delve into the fundamental cellular and molecular mechanisms underpinning aging, including mitochondrial dysfunction and cellular senescence, and elucidate their profound implications for the pathogenesis of various age-related diseases. Emphasis is placed on the importance of assessing key biomarkers of aging and biological age within the realm of pathology. We also scrutinize the interplay between cellular senescence and cancer biology as a central area of focus, underscoring its paramount significance in contemporary pathological research. Moreover, we shed light on the integration of anti-aging interventions that target fundamental aging processes, such as senolytics, mitochondria-targeted treatments, and interventions that influence epigenetic regulation within the domain of pathology research. In conclusion, the integration of geroscience concepts into pathological research heralds a transformative paradigm shift in our understanding of disease pathogenesis and promises breakthroughs in disease prevention and treatment.

Endothelial deficiency of insulin-like growth factor-1 receptor leads to blood-brain barrier disruption and accelerated endothelial senescence in mice, mimicking aspects of the brain aging phenotype

INTRODUCTION

Age-related blood-brain barrier (BBB) disruption, cerebromicrovascular senescence, and microvascular rarefaction substantially contribute to the pathogenesis of vascular cognitive impairment (VCI) and Alzheimer's disease (AD). Previous studies established a causal link between age-related decline in circulating levels of insulin-like growth factor-1 (IGF-1), cerebromicrovascular dysfunction, and cognitive decline. The aim of our study was to determine the effect of IGF-1 signaling on senescence, BBB permeability, and vascular density in middle-age and old brains.

METHODS

Accelerated endothelial senescence was assessed in senescence reporter mice (VE-Cadherin-CreERT2 /Igf1rfl/fl × p16-3MR) using flow cytometry. To determine the functional consequences of impaired IGF-1 input to cerebromicrovascular endothelial cells, BBB integrity and capillary density were studied in mice with endothelium-specific knockout of IGF1R (VE-Cadherin-CreERT2 /Igf1rfl/fl ) using intravital two-photon microscopy.

RESULTS

In VE-Cadherin-CreERT2 /Igf1rfl/fl mice: (1) there was an increased presence of senescent endothelial cells; (2) cumulative permeability of the microvessels to fluorescent tracers of different molecular weights (0.3-40 kDa) is significantly increased, as compared to that of control mice, whereas decline in cortical capillary density does not reach statistical significance.

CONCLUSIONS

These findings support the notion that IGF-1 signaling plays a crucial role in preserving a youthful cerebromicrovascular endothelial phenotype and maintaining the integrity of the BBB.

Human tendon-on-a-chip for modeling vascular inflammatory fibrosis

Understanding vascular inflammation and myofibroblast crosstalk is critical to developing therapies for fibrotic diseases. Here we report the development of a novel human Tendon-on-a-Chip (hToC) to model this crosstalk in peritendinous adhesions, a debilitating fibrotic condition affecting flexor tendon, which currently lacks biological therapies. The hToC enables cellular and paracrine interactions between a vascular compartment harboring endothelial cells and monocytes with a tissue hydrogel compartment containing tendon fibroblasts and macrophages. We find that the hToC replicates in vivo inflammatory and fibrotic phenotypes in preclinical and clinical samples, including myofibroblast differentiation and tissue contraction, excessive ECM deposition, and inflammatory cytokines secretion. We further show that the fibrotic phenotypes are driven by the transmigration of monocytes from the vascular to the tissue compartments of the chip. We demonstrate significant overlap in fibrotic transcriptional signatures in the hToC with human tenolysis samples, including mTOR signaling, a regulatory nexus of fibrosis across various organs. Treatment with rapamycin suppressed the fibrotic phenotype on the hToC, which validates the hToC as a preclinical alternative for investigating fibrosis and testing therapeutics.

The Role of Methionine-Rich Diet in Unhealthy Cerebrovascular and Brain Aging: Mechanisms and Implications for Cognitive Impairment

As aging societies in the western world face a growing prevalence of vascular cognitive impairment and Alzheimer's disease (AD), understanding their underlying causes and associated risk factors becomes increasingly critical. A salient concern in the western dietary context is the high consumption of methionine-rich foods such as red meat. The present review delves into the impact of this methionine-heavy diet and the resultant hyperhomocysteinemia on accelerated cerebrovascular and brain aging, emphasizing their potential roles in cognitive impairment. Through a comprehensive exploration of existing evidence, a link between high methionine intake and hyperhomocysteinemia and oxidative stress, mitochondrial dysfunction, inflammation, and accelerated epigenetic aging is drawn. Moreover, the microvascular determinants of cognitive deterioration, including endothelial dysfunction, reduced cerebral blood flow, microvascular rarefaction, impaired neurovascular coupling, and blood-brain barrier (BBB) disruption, are explored. The mechanisms by which excessive methionine consumption and hyperhomocysteinemia might drive cerebromicrovascular and brain aging processes are elucidated. By presenting an intricate understanding of the relationships among methionine-rich diets, hyperhomocysteinemia, cerebrovascular and brain aging, and cognitive impairment, avenues for future research and potential therapeutic interventions are suggested.

Blood-brain barrier dysfunction in intensive care unit

The central nervous system is characterized by a peculiar vascularization termed blood-brain barrier (BBB), which regulates the exchange of cells and molecules between the cerebral tissue and the whole body. BBB dysfunction is a life-threatening condition since its presence corresponds to a marker of severity in most diseases encountered in the intensive care unit (ICU). During critical illness, inflammatory response, cytokine release, and other phenomena activating the brain endothelium contribute to alterations in the BBB and increase its permeability to solutes, cells, nutrients, and xenobiotics. Moreover, patients in the ICU are often old, with underlying acute or chronic diseases, and overly medicated due to their critical condition; these factors could also contribute to the development of BBB dysfunction. An accurate diagnostic approach is critical for the identification of the mechanisms underlying BBB alterations, which should be rapidly managed by intensivists. Several methods were developed to investigate the BBB and assess its permeability. Nevertheless, in humans, exploration of the BBB requires the use of indirect methods. Imaging and biochemical methods can be used to study the abnormal passage of molecules through the BBB. In this review, we describe the structural and functional characteristics of the BBB, present tools and methods for probing this interface, and provide examples of the main diseases managed in the ICU that are related to BBB dysfunction.

Rapamycin Responds to Alzheimer's Disease: A Potential Translational Therapy

Alzheimer's disease (AD) is a sporadic or familial neurodegenerative disease of insidious onset with progressive cognitive decline. Although numerous studies have been conducted or are underway on AD, there are still no effective drugs to reverse the pathological features and clinical manifestations of AD. Rapamycin is a macrolide antibiotic produced by Streptomyces hygroscopicus. As a classical mechanistic target of rapamycin (mTOR) inhibitor, rapamycin has been shown to be beneficial in a variety of AD mouse and cells models, both before the onset of disease symptoms and the early stage of disease. Although many basic studies have demonstrated the therapeutic effects of rapamycin in AD, many questions and controversies remain. This may be due to the variability of experimental models, different modes of administration, dose, timing, frequency, and the availability of drug-targeting vehicles. Rapamycin may delay the development of AD by reducing β-amyloid (Aβ) deposition, inhibiting tau protein hyperphosphorylation, maintaining brain function in APOE ε4 gene carriers, clearing chronic inflammation, and improving cognitive dysfunction. It is thus expected to be one of the candidates for the treatment of Alzheimer's disease.

Integrated bioinformatic analysis and experimental validation for exploring the key molecular of brain inflammaging

Aims

Integrating bioinformatics and experimental validation to explore the mechanisms of inflammaging in the Brain.

Method

After dividing the GSE11882 dataset into aged and young groups, we identified co-expressed differentially expressed genes (DEGs) in different brain regions. Enrichment analysis revealed that the co-expressed DEGs were mainly associated with inflammatory responses. Subsequently, we identified 12 DEGs that were related to the inflammatory response and used the DGIdb website for drug prediction. By using both the least absolute shrinkage and selection operator (LASSO) and random forest (RF), four biomarkers were screened and an artificial neural network (ANN) was developed for diagnosis. Subsequently, the biomarkers were validated through animal studies. Then we utilized AgeAnno to investigate the roles of biomarkers at the single cell level. Next, a consensus clustering approach was used to classify the aging samples and perform differential analysis to identify inflammatory response-related genes. After conducting a weighted gene co-expression network analysis (WGCNA), we identified the genes that are correlated with both four brain regions and aging. Wayne diagrams were used to identify seven inflammaging-related genes in different brain regions. Finally, we performed immuno-infiltration analysis and identified macrophage module genes.

Key findings

Inflammaging may be a major mechanism of brain aging, and the regulation of macrophages by CX3CL1 may play a role in the development of inflammaging.

Significance

In summary, targeting CX3CL1 can potentially delay inflammaging and immunosenescence in the brain.

Therapeutic Induction of Collateral Flow

Therapeutic induction of collateral flow as a means to salvage tissue and improve outcome from acute ischemic stroke is a promising approach in the era in which endovascular therapy is no longer time-dependent but collateral-dependent. The importance of collateral flow enhancement as a therapeutic for acute ischemic stroke extends beyond those patients with large amounts of salvageable tissue. It also has the potential to extend the time window for reperfusion therapies in patients who are ineligible for endovascular thrombectomy. In addition, collateral enhancement may be an important adjuvant to neuroprotective agents by providing a more robust vascular route for which treatments can gain access to at risk tissue. However, our understanding of collateral hemodynamics, including under comorbid conditions that are highly prevalent in the stroke population, has hindered the efficacy of collateral flow augmentation for improving stroke outcome in the clinical setting. This review will discuss our current understanding of pial collateral function and hemodynamics, including vasoactivity that is critical for enhancing penumbral perfusion. In addition, mechanisms by which collateral flow can be increased during acute ischemic stroke to limit ischemic injury, that may be different depending on the state of the brain and vasculature prior to stroke, will also be reviewed.

Cell non-autonomous regulation of cerebrovascular aging processes by the somatotropic axis

Age-related cerebrovascular pathologies, ranging from cerebromicrovascular functional and structural alterations to large vessel atherosclerosis, promote the genesis of vascular cognitive impairment and dementia (VCID) and exacerbate Alzheimer's disease. Recent advances in geroscience, including results from studies on heterochronic parabiosis models, reinforce the hypothesis that cell non-autonomous mechanisms play a key role in regulating cerebrovascular aging processes. Growth hormone (GH) and insulin-like growth factor 1 (IGF-1) exert multifaceted vasoprotective effects and production of both hormones is significantly reduced in aging. This brief overview focuses on the role of age-related GH/IGF-1 deficiency in the development of cerebrovascular pathologies and VCID. It explores the mechanistic links among alterations in the somatotropic axis, specific macrovascular and microvascular pathologies (including capillary rarefaction, microhemorrhages, impaired endothelial regulation of cerebral blood flow, disruption of the blood brain barrier, decreased neurovascular coupling, and atherogenesis) and cognitive impairment. Improved understanding of cell non-autonomous mechanisms of vascular aging is crucial to identify targets for intervention to promote cerebrovascular and brain health in older adults.

Role of Vitamin D Deficiency in the Pathogenesis of Cardiovascular and Cerebrovascular Diseases

Deficiency in vitamin D (VitD), a lipid-soluble vitamin and steroid hormone, affects approximately 24% to 40% of the population of the Western world. In addition to its well-documented effects on the musculoskeletal system, VitD also contributes importantly to the promotion and preservation of cardiovascular health via modulating the immune and inflammatory functions and regulating cell proliferation and migration, endothelial function, renin expression, and extracellular matrix homeostasis. This brief overview focuses on the cardiovascular and cerebrovascular effects of VitD and the cellular, molecular, and functional changes that occur in the circulatory system in VitD deficiency (VDD). It explores the links among VDD and adverse vascular remodeling, endothelial dysfunction, vascular inflammation, and increased risk for cardiovascular and cerebrovascular diseases. Improved understanding of the complex role of VDD in the pathogenesis of atherosclerotic cardiovascular diseases, stroke, and vascular cognitive impairment is crucial for all cardiologists, dietitians, and geriatricians, as VDD presents an easy target for intervention.

The role of endothelial TRP channels in age-related vascular cognitive impairment and dementia

Transient receptor potential (TRP) proteins are part of a superfamily of polymodal cation channels that can be activated by mechanical, physical, and chemical stimuli. In the vascular endothelium, TRP channels regulate two fundamental parameters: the membrane potential and the intracellular Ca²⁺ concentration [(Ca²⁺)_i]. TRP channels are widely expressed in the cerebrovascular endothelium, and are emerging as important mediators of several brain microvascular functions (e.g., neurovascular coupling, endothelial function, and blood-brain barrier permeability), which become impaired with aging. Aging is the most significant risk factor for vascular cognitive impairment (VCI), and the number of individuals affected by VCI is expected to exponentially increase in the coming decades. Yet, there are currently no preventative or therapeutic treatments available against the development and progression of VCI. In this review, we discuss the involvement of endothelial TRP channels in diverse physiological processes in the brain as well as in the pathogenesis of age-related VCI to explore future potential neuroprotective strategies.

Role of endocrine PACAP in age-related diseases

Pituitary adenylate cyclase activating polypeptide (PACAP) is a conserved neuropeptide, which confers diverse anti-aging endocrine and paracrine/autocrine effects, including anti-apoptotic, anti-inflammatory and antioxidant action. The results of the in vivo and in vitro experiments show that increasing emphasis is being placed on the diagnostic/prognostic biomarker potential of this neuropeptide in a wide array of age-related diseases. After the initial findings regarding the presence and alteration of PACAP in different body fluids in physiological processes, an increasing number of studies have focused on the changes of its levels in various pathological conditions associated with advanced aging. Until 2016 - when the results of previous human studies were reviewed - a vast majority of the studies had dealt with age-related neurological diseases, like cerebrovascular and neurodegenerative diseases, multiple sclerosis, as well as some other common diseases in elderly such as migraine, traumatic brain injury and post-traumatic stress disorder, chronic hepatitis and nephrotic syndrome. The aim of this review is to summarize the old and the new results and highlight those 'classical' and emerging clinical fields in which PACAP may become subject to further investigation as a diagnostic and/or prognostic biomarker in age-related diseases.

FDA-Approved Kinase Inhibitors in Preclinical and Clinical Trials for Neurological Disorders

Cancers and neurological disorders are two major types of diseases. We previously developed a new concept termed "Aberrant Cell Cycle Diseases" (ACCD), revealing that these two diseases share a common mechanism of aberrant cell cycle re-entry. The aberrant cell cycle re-entry is manifested as kinase/oncogene activation and tumor suppressor inactivation, which are hallmarks of both tumor growth in cancers and neuronal death in neurological disorders. Therefore, some cancer therapies (e.g., kinase inhibition, tumor suppressor elevation) can be leveraged for neurological treatments. The United States Food and Drug Administration (US FDA) has so far approved 74 kinase inhibitors, with numerous other kinase inhibitors in clinical trials, mostly for the treatment of cancers. In contrast, there are dire unmet needs of FDA-approved drugs for neurological treatments, such as Alzheimer's disease (AD), intracerebral hemorrhage (ICH), ischemic stroke (IS), traumatic brain injury (TBI), and others. In this review, we list these 74 FDA-approved kinase-targeted drugs and identify those that have been reported in preclinical and/or clinical trials for neurological disorders, with a purpose of discussing the feasibility and applicability of leveraging these cancer drugs (FDA-approved kinase inhibitors) for neurological treatments.

Epigenetic regulation of aging: implications for interventions of aging and diseases

Aging is accompanied by the decline of organismal functions and a series of prominent hallmarks, including genetic and epigenetic alterations. These aging-associated epigenetic changes include DNA methylation, histone modification, chromatin remodeling, non-coding RNA (ncRNA) regulation, and RNA modification, all of which participate in the regulation of the aging process, and hence contribute to aging-related diseases. Therefore, understanding the epigenetic mechanisms in aging will provide new avenues to develop strategies to delay aging. Indeed, aging interventions based on manipulating epigenetic mechanisms have led to the alleviation of aging or the extension of the lifespan in animal models. Small molecule-based therapies and reprogramming strategies that enable epigenetic rejuvenation have been developed for ameliorating or reversing aging-related conditions. In addition, adopting health-promoting activities, such as caloric restriction, exercise, and calibrating circadian rhythm, has been demonstrated to delay aging. Furthermore, various clinical trials for aging intervention are ongoing, providing more evidence of the safety and efficacy of these therapies. Here, we review recent work on the epigenetic regulation of aging and outline the advances in intervention strategies for aging and age-associated diseases. A better understanding of the critical roles of epigenetics in the aging process will lead to more clinical advances in the prevention of human aging and therapy of aging-related diseases.

Rapamycin Cannot Reduce Seizure Susceptibility in Infantile Rats with Malformations of Cortical Development Lacking mTORC1 Activation

The mechanistic target of the rapamycin (mTOR) pathway is involved in cortical development. However, the efficacy of mTOR inhibitors in malformations of cortical dysplasia (MCD) outside of the tuberous sclerosis complex is unknown. We selected the MCD rat model with prenatal MAM exposure to test the efficacy of mTOR inhibitors in MCDs. We explored the early cortical changes of mTOR pathway protein expression in rats aged P15. We also monitored the early treatment effect of the mTOR inhibitor, rapamycin, on N-methyl-D-aspartate (NMDA)-induced spasms at P15 and their behavior in the juvenile stage. In vivo MR spectroscopy was performed after rapamycin treatment and compared with vehicle controls. There was no difference in mTORC1 pathway protein expression between MAM-exposed MCD rats and controls at P15, and prolonged treatment of rapamycin had no impact on NMDA-induced spasms despite poor weight gain. Prenatal MAM-exposed juvenile rats treated with rapamycin showed increased social approaching and freezing behavior during habituation. MR spectroscopy showed altered neurometabolites, including Gln, Glu+Gln, Tau, and Cr. Despite behavioral changes and in vivo neurometabolic alteration with early prolonged rapamycin treatment, rapamycin had no effect on spasms susceptibility in prenatal MAM-exposed infantile rats with MCD without mTORC1 activation. For MAM-exposed MCD rats without mTORC1 activation, treatment options outside of mTOR pathway inhibitors should be explored.

Electroacupuncture Synergistically Inhibits Proinflammatory Cytokine Production and Improves Cognitive Function in Rats with Cognitive Impairment due to Hepatic Encephalopathy through p38MAPK/STAT3 and TLR4/NF-κB Signaling Pathways

Objective

To investigate the effect of electroacupuncture (EA) on cognitive dysfunction in rats with hepatic encephalopathy and its underlying mechanism.

Methods

Fifty Wistar rats were randomly divided into a normal group (n = 10) and model group (n = 40). Rat models of hepatic encephalopathy were established by administration of carbon tetrachloride and thioacetamide for a total of 12 weeks. At the 9th week after modeling, rats with cognitive impairment in the model group were identified by conducting the Morris water maze test, which were then randomly divided into a control group (CCl₄) and treatment groups including EA group (CCl₄ + EA), lactulose group (CCl₄ + Lac), and EA plus lactulose group (CCl₄ + CM), with 9 rats in each group. At the end of the 9th week, rats in CCl₄ + Lac and CCl₄ + CM groups had lactulose gavage at a dose of 10 mL/kg body weight, while normal control and CCl₄ groups had gavage with the same volume of normal saline once a day for 21 days until the end of the experiment. Rats in CCl₄ + EA and CCl₄ + CM groups underwent acupuncture at Baihui (GV[DU]20), Shenting (GV[DU]24), and Zusanli (ST36) acupoints, among which EA at Baihui and Shenting acupoints were given once daily for 30 min lasting for 21 consecutive days. The effect of the treatment was measured by the Morris water maze test for learning and memory ability and magnetic resonance spectroscopy (MRS) for neuronal metabolism in the hippocampus of rats with hepatic encephalopathy. Pathological change in the rat hippocampus was observed by HE staining, while serum ammonia and liver function markers were detected. Western blot and real-time fluorescent quantitative PCR were used to detect the expressions of specific genes and proteins in the brain tissue.

Results

Compared with those in the control group, rats undergoing EA had significantly shortened escape latency and increased number of platform crossing. H&E staining confirmed that EA improved brain tissue necrosis and ameliorated nuclear pyknosis in rats with hepatic encephalopathy. Significantly decreased levels of serum ammonia, alanine aminotransferase (ALT), aspartate transaminase (AST), total bilirubin (TBil), and total bile acid (TBA) were observed in rats undergoing EA, as well as improved levels of total protein (TP) and albumin (ALB). In addition, EA inhibited the brain expressions of TNF-α, IL-1β, IL-6, iNOS, TLR4, MyD88, NF-κB, p38MAPK, phosphorylated (p)-p38MAPK, STAT3, and p-STAT3 genes, as well as protein expressions of TNF-α, IL-6, TLR4, MyD88, NF-κB, p38MAPK, p-p38MAPK, STAT3, and p-STAT3. MRS showed increased Glx/Cr and decreased NAA/Cr, Cho/Cr and mI/Cr in the control group, and EA significantly reversed such changes in Glx/Cr and mI/Cr values.

Conclusion

EA ameliorated the production of excessive proinflammatory cytokines in the hippocampus of rats with cognitive dysfunction secondary to hepatic encephalopathy, which also gave rise to subsequent changes such as reduced blood ammonia level, brain-protective activated astrocytes, and lower degree of brain tissue injury. The p38MAPK/STAT3 and TLR4/MyD88/NF-κB signaling pathways may be involved. EA can also improve the metabolism of NAA and Cho in the rat hippocampus and thereby improve learning and memory abilities.