Calorie restriction and stroke

Intermittent fasting induced cerebral ischemic tolerance altered gut microbiome and increased levels of short-chain fatty acids to a beneficial phenotype

Preconditioning-induced cerebral ischemic tolerance is known to be a beneficial adaptation to protect the brain in an unavoidable event of stroke. We currently demonstrate that a short bout (6 weeks) of intermittent fasting (IF; 15 h fast/day) induces similar ischemic tolerance to that of a longer bout (12 weeks) in adult C57BL/6 male mice subjected to transient middle cerebral artery occlusion (MCAO). In addition, the 6 weeks IF regimen induced ischemic tolerance irrespective of age (3 months or 24 months) and sex. Mice subjected to transient MCAO following IF showed improved motor function recovery (rotarod and beam walk tests) between days 1 and 14 of reperfusion and smaller infarcts (T2-MRI) on day 1 of reperfusion compared with age/sex matched ad libitum (AL) controls. Diet influences the gut microbiome composition and stroke is known to promote gut bacterial dysbiosis. We presently show that IF promotes a beneficial phenotype of gut microbiome following transient MCAO compared with AL cohort. Furthermore, post-stroke levels of short-chain fatty acids (SCFAs), which are known to be neuroprotective, are higher in the fecal samples of the IF cohort compared with the AL cohort. Thus, our studies indicate the efficacy of IF in protecting the brain after stroke, irrespective of age and sex, probably by altering gut microbiome and SCFA production.

Blood and Brain Metabolites after Cerebral Ischemia

The study of an organism's response to cerebral ischemia at different levels is essential to understanding the mechanism of the injury and protection. A great interest is devoted to finding the links between quantitative metabolic changes and post-ischemic damage. This work aims to summarize the outcomes of the most studied metabolites in brain tissue-lactate, glutamine, GABA (4-aminobutyric acid), glutamate, and NAA (N-acetyl aspartate)-regarding their biological function in physiological conditions and their role after cerebral ischemia/reperfusion. We focused on ischemic damage and post-ischemic recovery in both experimental-including our results-as well as clinical studies. We discuss the role of blood glucose in view of the diverse impact of hyperglycemia, whether experimentally induced, caused by insulin resistance, or developed as a stress response to the cerebral ischemic event. Additionally, based on our and other studies, we analyze and critically discuss post-ischemic alterations in energy metabolites and the elevation of blood ketone bodies observed in the studies on rodents. To complete the schema, we discuss alterations in blood plasma circulating amino acids after cerebral ischemia. So far, no fundamental brain or blood metabolite(s) has been recognized as a relevant biological marker with the feasibility to determine the post-ischemic outcome or extent of ischemic damage. However, studies from our group on rats subjected to protective ischemic preconditioning showed that these animals did not develop post-ischemic hyperglycemia and manifested a decreased metabolic infringement and faster metabolomic recovery. The metabolomic approach is an additional tool for understanding damaging and/or restorative processes within the affected brain region reflected in the blood to uncover the response of the whole organism via interorgan metabolic communications to the stressful cerebral ischemic challenge.

The Ketogenic Diet but not Hydroxycitric Acid Keeps Brain Mitochondria Quality Control and mtDNA Integrity Under Focal Stroke

Mitochondrial dysfunction in the ischemic brain is one of the hallmarks of stroke. Dietary interventions such as the ketogenic diet and hydroxycitric acid supplementation (a caloric restriction mimetic) may potentially protect neurons from mitochondrial damage induced by focal stroke in mice. We showed that in control mice, the ketogenic diet and the hydroxycitric acid did not impact significantly on the mtDNA integrity and expression of genes involved in the maintenance of mitochondrial quality control in the brain, liver, and kidney. The ketogenic diet changed the bacterial composition of the gut microbiome, which via the gut-brain axis may affect the increase in anxiety behavior and reduce mice mobility. The hydroxycitric acid causes mortality and suppresses mitochondrial biogenesis in the liver. Focal stroke modelling caused a significant decrease in the mtDNA copy number in both ipsilateral and contralateral brain cortex and increased the levels of mtDNA damage in the ipsilateral hemisphere. These alterations were accompanied by a decrease in the expression of some of the genes involved in maintaining mitochondrial quality control. The ketogenic diet consumption before stroke protects mtDNA in the ipsilateral cortex, probably via activation of the Nrf2 signaling. The hydroxycitric acid, on the contrary, increased stroke-induced injury. Thus, the ketogenic diet is the most preferred variant of dietetic intervention for stroke protection compared with the hydroxycitric acid supplementation. Our data confirm some reports about hydroxycitric acid toxicity, not only for the liver but also for the brain under stroke condition.

Phytotherapeutic targeting of the mitochondria in neurodegenerative disorders

Neurodegenerative diseases are characterized by degeneration or cellular atrophy within specific structures of the brain. Neurons are the major target of neurodegeneration. Neurons utilize 75-80% of the energy produced in the brain. This energy is either formed by utilizing the glucose provided by the cerebrovascular blood flow or by the in-house energy producers, mitochondria. Mitochondrial dysfunction has been associated with neurodegenerative diseases. But recently it has been noticed that neurodegenerative diseases are often associated with cerebrovascular diseases. Cerebral blood flow requires vasodilation which to an extent regulated by mitochondria. We hypothesize that when mitochondrial functioning is disrupted, it is not able to supply energy to the neurons. This disruption also affects cerebral blood flow, further reducing the possibilities of energy supply. Loss of sufficient energy leads to neuronal dysfunction, atrophy, and degeneration. In this chapter, we will discuss the metabolic modifications of mitochondria in aging-related neurological disorders and the potential of phytocompounds targeting them.

Beneficial effects of time and energy restriction diets on the development of experimental acute kidney injury in Rat: Bax/Bcl-2 and histopathological evaluation

People's lifestyles and, especially, their eating habits affect their health and the functioning of the organs in their bodies, including the kidneys. One's diet influences the cells' responses to stressful conditions such as acute kidney injury (AKI). This study aims to determine the preconditioning effects of four different diets: energy restriction (ER) diet, time restriction (TR) eating, intermittent fasting (IF), and high-fat diet (HF) on histopathological indices of the kidney as well as the molecules involved in apoptosis during AKI. Adult male rats underwent ER, TR, IF, and HF diets for eight weeks. Then, AKI was induced, and renal function indices, histopathological indices, and molecules involved in apoptosis were measured. In animals with AKI, urinary albumin excretion, serum urea, creatinine and, Bax/Bcl-2 ratio increased in the kidney, while renal eGFR decreased. ER and TR diets improved renal parameters and prevented an increase in the Bax/Bcl-2 ratio. The IF diet improved renal parameters but had no effect on the Bax/Bcl-2 ratio. On the other hand, the HF diet worsened renal function and increased the Bax/Bcl-2 ratio. Histopathological examination also showed improved kidney conditions in the ER and TR groups and more damage in the HF group. This study demonstrated that ER and TR diets have renoprotective effects on AKI and possibly cause the resistance of kidney cells to damage by reducing the Bax/Bcl-2 ratio and improving apoptotic conditions.

Ketogenic Diet and Ketone Bodies against Ischemic Injury: Targets, Mechanisms, and Therapeutic Potential

The ketogenic diet (KD) has been used as a treatment for epilepsy since the 1920s, and its role in the prevention of many other diseases is now being considered. In recent years, there has been an intensive investigation on using the KD as a therapeutic approach to treat acute pathologies, including ischemic ones. However, contradictory data are observed for the effects of the KD on various organs after ischemic injury. In this review, we provide the first systematic analysis of studies conducted from 1980 to 2022 investigating the effects and main mechanisms of the KD and its mimetics on ischemia-reperfusion injury of the brain, heart, kidneys, liver, gut, and eyes. Our analysis demonstrated a high diversity of both the composition of the used KD and the protocols for the treatment of animals, which could be the reason for contradictory effects in different studies. It can be concluded that a true KD or its mimetics, such as β-hydroxybutyrate, can be considered as positive exposure, protecting the organ from ischemia and its negative consequences, whereas the shift to a rather similar high-calorie or high-fat diet leads to the opposite effect.

Biological age and environmental risk factors for dementia and stroke: Molecular mechanisms

Since the development of antibiotics and vaccination, as well as major improvements in public hygiene, the main risk factors for morbidity and mortality are age and chronic exposure to environmental factors, both of which can interact with genetic predispositions. As the average age of the population increases, the prevalence and costs of chronic diseases, especially neurological conditions, are rapidly increasing. The deleterious effects of age and environmental risk factors, develop chronically over relatively long periods of time, in contrast to the relatively rapid deleterious effects of infectious diseases or accidents. Of particular interest is the hypothesis that the deleterious effects of environmental factors may be mediated by acceleration of biological age. This hypothesis is supported by evidence that dietary restriction, which universally delays age-related diseases, also ameliorates deleterious effects of environmental factors. Conversely, both age and environmental risk factors are associated with the accumulation of somatic mutations in mitotic cells and epigenetic modifications that are a measure of "biological age", a better predictor of age-related morbidity and mortality than chronological age. Here we review evidence that environmental risk factors such as smoking and air pollution may also drive neurological conditions, including Alzheimer's Disease, by the acceleration of biological age, mediated by cumulative and persistent epigenetic effects as well as somatic mutations. Elucidation of such mechanisms could plausibly allow the development of interventions which delay deleterious effects of both aging and environmental risk factors.

Calorie restriction or dietary restriction: how far they can protect the brain against neurodegenerative diseases?

Finding the correct nutritional intervention is one of the biggest challenges in treating patients with neurodegenerative diseases. In general, these patients develop strong metabolic alterations, resulting in lower treatment efficacy and higher mortality rates. However, there are still many open questions regarding the effectiveness of dietary interventions in neurodiseases. Some studies have shown that a reduction in calorie intake activates key pathways that might be important for preventing or slowing down the progression of such diseases. However, it is still unclear whether these neuroprotective effects are associated with an overall reduction in calories (hypocaloric diet) or a specific nutrient restriction (diet restriction). Therefore, here we discuss how commonly or differently hypocaloric and restricted diets modulate signaling pathways and how these changes can protect the brain against neurodegenerative diseases.

Beneficial Effects on Brain Micro-Environment by Caloric Restriction in Alleviating Neurodegenerative Diseases and Brain Aging

Aging and neurodegenerative diseases are frequently associated with the disruption of the extracellular microenvironment, which includes mesenchyme and body fluid components. Caloric restriction (CR) has been recognized as a lifestyle intervention that can improve long-term health. In addition to preventing metabolic disorders, CR has been shown to improve brain health owing to its enhancing effect on cognitive functions or retarding effect on the progression of neurodegenerative diseases. This article summarizes current findings regarding the neuroprotective effects of CR, which include the modulation of metabolism, autophagy, oxidative stress, and neuroinflammation. This review may offer future perspectives for brain aging interventions.

Neurons die with heightened but functional macro- and chaperone mediated autophagy upon increased amyloid-ß induced toxicity with region-specific protection in prolonged intermittent fasting

Alzheimer's disease (AD) is a devastating neurodegenerative condition with significant socio-economic impact that is exacerbated by the rapid increase in population aging, particularly impacting already burdened health care systems of poorly resourced countries. Accumulation of the amyloid-β (Aβ) peptide, generated through amyloid precursor protein (APP) processing, manifesting in senile plaques, is a well-established neuropathological feature. Aβ plays a key role in driving synaptic dysfunction, neuronal cell loss, glial cell activation and oxidative stress associated with the pathogenesis of AD. Thus, the enhanced clearance of Aβ peptide though modulation of the mechanisms that regulate intracellular Aβ metabolism and clearance during AD progression have received major attention. Autophagy, a lysosome-based major proteolytic pathway, plays a crucial role in intracellular protein quality control and has been shown to contribute to the clearance of Aβ peptide. However, to what extent autophagy activity remains upregulated and functional in the process of increasing Aβ neurotoxicity is largely unclear. Here, we investigated the extent of neuronal toxicity in vitro by characterising autophagic flux, the expression profile of key amyloidogenic proteins, and proteins associated with prominent subtypes of the autophagy pathway to dissect the interplay between the engagement of proteolytic pathways and cell death onset in the context of APP overexpression. Moreover, we assessed the neuroprotective effects of a caloric restriction regime in vivo on the modulation of autophagy in specific brain regions. Our results reveal that autophagy is upregulated in the presence of high levels of APP and Aβ and remains heightened and functional despite concomitant apoptosis induction, suggestive of a mismatch between autophagy cargo generation and clearance capacity. These findings were confirmed when implementing a prolonged intermittent fasting (IF) intervention in a model of paraquat-induced neuronal toxicity, where markers of autophagic activity were increased, while apoptosis onset and lipid peroxidation were robustly decreased in brain regions associated with neurodegeneration. This work highlights that especially caloric restriction mimetics and controlled prolonged IF may indeed be a highly promising therapeutic strategy at all stages of AD-associated pathology progression, for a cell-inherent and cell specific augmentation of Aβ clearance through the powerful engagement of autophagy and thereby robustly contributing to neuronal protection.

Analysis of Metabolite and Lipid Association Networks Reveals Molecular Mechanisms Associated with 3-Month Mortality and Poor Functional Outcomes in Patients with Acute Ischemic Stroke after Thrombolytic Treatment with Recombinant Tissue Plasminogen Activator

Here, we present an integrated multivariate, univariate, network reconstruction and differential analysis of metabolite–metabolite and metabolite–lipid association networks built from an array of 18 serum metabolites and 110 lipids identified and quantified through nuclear magnetic resonance spectroscopy in a cohort of 248 patients, of which 22 died and 82 developed a poor functional outcome within 3 months from acute ischemic stroke (AIS) treated with intravenous recombinant tissue plasminogen activator. We explored differences in metabolite and lipid connectivity of patients who did not develop a poor outcome and who survived the ischemic stroke from the related opposite conditions. We report statistically significant differences in the connectivity patterns of both low- and high-molecular-weight metabolites, implying underlying variations in the metabolic pathway involving leucine, glycine, glutamine, tyrosine, phenylalanine, citric, lactic, and acetic acids, ketone bodies, and different lipids, thus characterizing patients’ outcomes. Our results evidence the promising and powerful role of the metabolite–metabolite and metabolite–lipid association networks in investigating molecular mechanisms underlying AIS patient’s outcome.

Dietary pattern and telomere length in preschool children in a middle-income country

Telomere length (TL) has been associated with lifestyle and dietary pattern. However, the available evidence on this association in children is scarce, especially in low- and middle-income countries (LMICs). Therefore, this study aimed to evaluate the association of dietary pattern and leukocyte TL (LTL) in preschool children, Sabzevar, Iran (2017). This cross-sectional study was based on 187 preschool children (aged 5 to 7) recruited from 27 kindergartens. Nutrition information including amounts of consumed dairy products, meat and processed meat products, nuts and seeds, white bread and refined grains, fruits, vegetables, simple sugars, fats and drinks was obtained through a questionnaire. Linear mixed-effects models were fitted with polymerase chain reaction (PCR) plate ID and kindergartens as random effects to estimate the association of each food group consumption with LTL, controlled for relevant covariates. Higher consumption of dairy products and sugar was associated with shorter LTL (β = -0.180, 95% confidence interval [CI]: -0.276, -0.085, P value <0.001 and β = -0.139, 95% CI: -0.193, -0.086, P value <0.001, respectively). An increase in consumption of fish, nuts and seeds, coloured fruits, green leafy vegetables, cruciferous vegetables and olive was significantly associated with the increase in relative LTL. The associations for the consumption of legumes, other fruits, yellow and orange vegetables, red meat, egg, white bread and refined grains, solid and liquid fats, processed meats, potato chips, carbonated drinks, tea (black) and soft drinks groups were not statistically significant. Our findings showed that there was an association between the consumption of certain food groups with LTL.

Overnight Caloric Restriction Prior to Cardiac Arrest and Resuscitation Leads to Improved Survival and Neurological Outcome in a Rodent Model

While interest toward caloric restriction (CR) in various models of brain injury has increased in recent decades, studies have predominantly focused on the benefits of chronic or intermittent CR. The effects of ultra-short, including overnight, CR on acute ischemic brain injury are not well studied. Here, we show that overnight caloric restriction (75% over 14 h) prior to asphyxial cardiac arrest and resuscitation (CA) improves survival and neurological recovery as measured by, behavioral testing on neurological deficit scores, faster recovery of quantitative electroencephalography (EEG) burst suppression ratio, and complete prevention of neurodegeneration in multiple regions of the brain. We also show that overnight CR normalizes stress-induced hyperglycemia, while significantly decreasing insulin and glucagon production and increasing corticosterone and ketone body production. The benefits seen with ultra-short CR appear independent of Sirtuin 1 (SIRT-1) and brain-derived neurotrophic factor (BDNF) expression, which have been strongly linked to neuroprotective benefits seen in chronic CR. Mechanisms underlying neuroprotective effects remain to be defined, and may reveal targets for providing protection pre-CA or therapeutic interventions post-CA. These findings are also of high importance to basic sciences research as we demonstrate that minor, often-overlooked alterations to pre-experimental dietary procedures can significantly affect results, and by extension, research homogeneity and reproducibility, especially in acute ischemic brain injury models.

Long-Term Alternating Fasting Increases Interleukin-13 in the Gerbil Hippocampus, But Does Not Protect BBB and Pyramidal Neurons From Ischemia-Reperfusion Injury

It is questionable whether intermittent fasting (IF) protects against brain ischemic injury. This study examined whether IF increased anti-inflammatory cytokines and protected neurons from ischemia-reperfusion injury in the gerbil hippocampus. Gerbils were subjected to 1-day alternating fasting as IF for 1, 2, or 3 months and assigned to sham or 5 min of transient ischemia. We examined the changes in anti-inflammatory cytokines (IL-4 and IL-13), neurons and IgG by immunohistochemistry or immunofluorescence staining in the cornu ammonis 1 (CA1) region of the hippocampus before and after ischemia. IF increased IL-13 immunoreactivity in the CA1 region before ischemia, but did not affect IL-4 immunoreactivity. After ischemia, IL-13 and 4 immunoreactivities in the CA1 region were significantly lower in IF gerbils than in non-IF gerbils. In the IF gerbils, the CA1 pyramidal neurons were not protected from ischemic injury; in these gerbils, strong IgG immunoreactivity was seen in the CA1 parenchyma, indicating leakage of the BBB. In brief, IF increased IL-13 in the CA1 region, but these neurons were not protected from transient ischemic injury evidenced by IgG immunoreactivity in the CA1 parenchyma. This study indicates that IF increased some anti-inflammatory cytokines but did not afford neuroprotection against ischemic insults via BBB disruption.

Molecular Mechanisms of Intermittent Fasting-induced Ischemic Tolerance

Diet is a significant factor in determining human well-being. Excessive eating and/or diets with higher than needed amounts of carbohydrates, salt, and fat are known to cause metabolic disorders and functional changes in the body. To compensate the ill effects, many designer diets including the Mediterranean diet, the Okinawa diet, vegetarian/vegan diets, keto diet, anti-inflammatory diet, and the anti-oxidant diet have been introduced in the past 2 decades. While these diets are either enriched or devoid of one or more specific components, a better way to control diet is to limit the amount of food consumed. Caloric restriction (CR), which involves limiting the amount of food consumed rather than eliminating any specific type of food, as well as intermittent fasting (IF), which entails limiting the time during which food can be consumed on a given day, have gained popularity because of their positive effects on human health. While the molecular mechanisms of these 2 dietary regimens have not been fully deciphered, they are known to prolong the life span, control blood pressure, and blood glucose levels. Furthermore, CR and IF were both shown to decrease the incidence of heart attack and stroke, as well as their ill effects. In particular, IF is thought to promote metabolic switching by altering gene expression profiles leading to reduced inflammation and oxidative stress, while increasing plasticity and regeneration.

Dietary Restriction and Epigenetics: Part I

Biological aging occurs concomitantly with chronological aging and is commonly burdened by the development of age-related conditions, such as neurodegenerative, cardiovascular, and a myriad of metabolic diseases. With a current global shift in disease epidemiology associated with aging and the resultant social, economic, and healthcare burdens faced by many countries, the need to achieve successful aging has fueled efforts to address this problem. Aging is a complex biological phenomenon that has confounded much of the historical research effort to understand it, with still limited knowledge of the underlying molecular mechanisms. Interestingly, dietary restriction (DR) is one intervention that produces anti-aging effects from simple organisms to mammals. Research into DR has revealed robust systemic effects that can result in attenuation of age-related diseases via a myriad of molecular mechanisms. Given that numerous age-associated diseases are often polygenic and affect individuals differently, it is possible that they are confounded by interactions between environmental influences and the genome, a process termed 'epigenetics'. In part one of the review, we summarize the different variants of DR regimens and their corresponding mechanism(s) and resultant effects, as well as in-depth analysis of current knowledge of the epigenetic landscape.

Genome-Wide Transcriptome Analysis Reveals Intermittent Fasting-Induced Metabolic Rewiring in the Liver

Scope: Intermittent fasting (IF) has been extensively reported to promote improved energy homeostasis and metabolic switching. While IF may be a plausible strategy to ameliorate the epidemiological burden of disease in many societies, our understanding of the underlying molecular mechanisms behind such effects is still lacking. The present study has sought to investigate the relationship between IF and changes in gene expression. We focused on the liver, which is highly sensitive to metabolic changes due to energy status. Mice were randomly assigned to ad libitum feeding or IF for 16 hours per day or for 24 hours on alternate days for 3 months, after which genome-wide transcriptome analysis of the liver was performed using RNA sequencing. Our findings revealed that IF caused robust transcriptomic changes in the liver that led to a complex array of metabolic changes. We also observed that the IF regimen produced distinct profiles of transcriptomic changes, highlighting the significance of temporally different periods of energy restriction. Our results suggest that IF can regulate metabolism via transcriptomic mechanisms and provide insight into how genetic interactions within the liver might lead to the numerous metabolic benefits of IF.

ACC1 (Acetyl Coenzyme A Carboxylase 1) Is a Potential Immune Modulatory Target of Cerebral Ischemic Stroke

Background and Purpose—

Cerebral ischemic stroke elicits profound responses of CD4 + T cells, which in turn significantly affect the ischemic brain injury. ACC1 (acetyl coenzyme A carboxylase 1) is a key enzyme that has been recently found to propagate CD4 + T cell–associated inflammation by mediating de novo fatty acid synthesis; however, its role in the context of ischemic stroke remains unknown.

Methods—

Focal cerebral ischemia was induced by transient middle cerebral artery occlusion for 60 minutes in mice. Seahorse XF glycolysis assay and targeted lipidomic profiling were used to detect metabolic changes in CD4 + T cell after stroke. CD4 cre mice were crossed with ACC1 fl/fl mice to generate the CD4 + T-cell–specific deletion of ACC1 (CD4 cre ACC1 fl/fl mice) mice. Pretreatment with calorie restriction (CR; with 30% reduction of food for 4 weeks before middle cerebral artery occlusion) or post-treatment with ACC1 inhibitor, soraphen A were both used to test the effect of ACC1 modulation on poststroke neuroinflammation.

Results—

Cerebral ischemic stroke increased glycolysis and fatty acid synthesis in peripheral CD4 + T cells, in which the expression of ACC1 was also upregulated. CR downregulated the expression of ACC1 in CD4 + T cells after stroke. Both CD4 cre ACC1 fl/fl mice and CR-pretreated mice exhibited significantly reduced ischemic brain injury and preserved the balance of peripheral regulatory T cells/T helper 17 (Th17) cells. Furthermore, conditional knockout of ACC1 in CD4 + T cells attenuated the protection exerted by CR both on ischemic brain injury and peripheral balance of regulatory T cells/Th17 cells. Pharmacological inhibition of ACC1 after middle cerebral artery occlusion attenuates neuroinflammation, preserves regulatory T cells/Th17 balance, and improves neurological outcomes after ischemic stroke.

Conclusions—

ACC1 is a novel immune metabolic modulation target to balance the regulatory T cells and Th17 cells and blunt neuroinflammation after stroke. Inhibition of ACC1 can be a previously unrecognized mechanism that underlies CR-afforded neuroprotection against cerebral ischemic stroke.

Negative Conditioning of Mitochondrial Dysfunction in Age-related Neurodegenerative Diseases

Mitochondrial dysfunction is regarded as one of the major causes of neuronal injury in age-associated neurodegenerative diseases and stroke. Mitochondrial dysfunction leads to increased reactive oxygen species production, causing mitochondrial DNA mutations, which then results in pathological conditions. Negative conditioning of mitochondrial dysfunction via pharmacological inhibition, phytochemicals, and dietary restriction serve as an avenue for therapeutic intervention to improve mitochondrial quality and function. Here, we focus primarily on mitochondrial biology, evidence for mitochondrial dysfunction in neurodegenerative conditions such as dementia and stroke, and the possibility of using negative conditioning to restore or preserve mitochondrial function in these diseases.

Diabesity and brain disturbances: A metabolic perspective

The last decades have been marked by an increased prevalence in non-communicable diseases such as obesity and type 2 diabetes (T2D) as well as by population aging and age-related (brain) diseases. The current notion that the brain and the body are interrelated units is gaining the attention of the scientific and medical community. Growing evidence demonstrates that there is a significant overlap in risk, comorbidity, and pathophysiological mechanisms across obesity, T2D and brain disturbances; settings that seem to be worsened when both obesity and T2D occur simultaneously, the so-called diabesity. Thereupon, there is a great concern to critically appraise and understand the mechanisms by which diabesity can affect brain responses, and may accelerate the decline in brain health. In this framework, metabolic disturbances mediated by altered insulin signaling and mitochondrial function arise among the multifactorial interactions described to occur between obesity, T2D and neurocognitive deficits. In this review we have compiled all the notions and evidence describing how diabesity negatively influences brain function putting the emphasis on insulin signaling pathway disturbances and mitochondrial anomalies. We also debate lifestyle interventions as amenable strategies to lessen metabolic anomalies and, consequently, diabesity-associated brain alterations.

Effect of caloric restriction on depression

Recently, most of evidence shows that caloric restriction could induce antidepressant‐like effects in animal model of depression. Based on studies of the brain–gut axis, some signal pathways were common between the control of caloric restriction and depression. However, the specific mechanism of the antidepressant‐like effects induced by caloric restriction remains unclear. Therefore, in this article, we summarized clinical and experimental studies of caloric restriction on depression. This review may provide a new therapeutic strategy for depression.

Present Status and Future Challenges of New Therapeutic Targets in Preclinical Models of Stroke in Aged Animals with/without Comorbidities

The aging process, comorbidities, and age-associated diseases are closely dependent on each other. Cerebral ischemia impacts a wide range of systems in an age-dependent manner. However, the aging process has many facets which are influenced by the genetic background and epigenetic or environmental factors, which can explain why some people age differently than others. Therefore, there is an urgent need to identify age-related changes in body functions or structures that increase the risk for stroke and which are associated with a poor outcome. Multimodal imaging, electrophysiology, cell biology, proteomics, and transcriptomics, offer a useful approach to link structural and functional changes in the aging brain, with or without comorbidities, to post-stroke rehabilitation. This can help us to improve our knowledge about senescence firstly, and in this context, aids in elucidating the pathophysiology of age-related diseases that allows us to develop therapeutic strategies or prevent diseases. These processes, including potential therapeutical interventions, need to be studied first in relevant preclinical models using aged animals, with and without comorbidities. Therefore, preclinical research on ischemic stroke should consider age as the most important risk factor for cerebral ischemia. Furthermore, the identification of effective therapeutic strategies, corroborated with successful translational studies, will have a dramatic impact on the lives of millions of people with cerebrovascular diseases.

Intermittent fasting promotes prolonged associative interactions during synaptic tagging/capture by altering the metaplastic properties of the CA1 hippocampal neurons

Metaplasticity is the inherent property of a neuron or neuronal population to undergo activity-dependent changes in neural function that modulate subsequent synaptic plasticity. Here we studied the effect of intermittent fasting (IF) in governing the interactions of associative plasticity mechanisms in the pyramidal neurons of rat hippocampal area CA1. Late long-term potentiation and its associative mechanisms such as synaptic tagging and capture at an interval of 120 min were evaluated in four groups of animals, AL (Ad libitum), IF12 (daily IF for 12 h), IF16 (daily IF for 16 h) and EOD (every other day IF for 24 h). IF had no visible effect on the early or late plasticity but it manifested a critical role in prolonging the associative interactions between weak and strong synapses at an interval of 120 min in IF16 and EOD animals. However, both IF12 and AL did not show associativity at 120 min. Plasticity genes such as Bdnf and Prkcz, which are well known for their expressions in late plasticity and synaptic tagging and capture, were significantly upregulated in IF16 and EOD in comparison to AL. Specific inhibition of brain derived neurotropic factor (BDNF) prevented the prolonged associativity expressed in EOD. Thus, daily IF for 16 h or more can be considered to enhance the metaplastic properties of synapses by improving their associative interactions that might translate into animprovedmemoryformation.

2,4 DNP improves motor function, preserves medium spiny neuronal identity, and reduces oxidative stress in a mouse model of Huntington's disease

Huntington's disease (HD) is a neurodegenerative disorder caused by a CAG repeat expansion in the first exon of the gene huntingtin. There is no treatment to prevent or delay the disease course of HD currently. Oxidative stress and mitochondrial dysfunction have emerged as key determinants of the disease progression in HD. Therefore, counteracting mutant huntingtin (mHtt)-induced oxidative stress and mitochondrial dysfunction appears as a new approach to treat this devastating disease. Interestingly, mild mitochondrial uncoupling improves neuronal resistance to stress and facilitates neuronal survival. Mild mitochondrial uncoupling can be induced by the proper dose of 2,4-dinitrophenol (DNP), a proton ionophore that was previously used for weight loss. In this study, we evaluated the effects of chronic administration of DNP at three doses (0.5, 1, 5mg/kg/day) on mHtt-induced behavioral deficits and cellular abnormalities in the N171-82Q HD mouse model. DNP at a low dose (1mg/kg/day) significantly improved motor function and preserved medium spiny neuronal marker DARPP32 and postsynaptic protein PSD95 in the striatum of HD mice. Further mechanistic study suggests that DNP at this dose reduced oxidative stress in HD mice, which was indicated by reduced levels of F2-isoprostanes in the brain of HD mice treated with DNP. Our data indicated that DNP provided behavioral benefit and neuroprotective effect at a weight neutral dose in HD mice, suggesting that the potential value of repositioning DNP to HD treatment is warranted in well-controlled clinical trials in HD.

FABP4/aP2 Regulates Macrophage Redox Signaling and Inflammasome Activation via Control of UCP2

Obesity-linked metabolic disease is mechanistically associated with the accumulation of proinflammatory macrophages in adipose tissue, leading to increased reactive oxygen species (ROS) production and chronic low-grade inflammation. Previous work has demonstrated that deletion of the adipocyte fatty acid-binding protein (FABP4/aP2) uncouples obesity from inflammation via upregulation of the uncoupling protein 2 (UCP2). Here, we demonstrate that ablation of FABP4/aP2 regulates systemic redox capacity and reduces cellular protein sulfhydryl oxidation and, in particular, oxidation of mitochondrial protein cysteine residues. Coincident with the loss of FABP4/aP2 is the upregulation of the antioxidants superoxide dismutase (SOD2), catalase, methionine sulfoxide reductase A, and the 20S proteasome subunits PSMB5 and αβ. Reduced mitochondrial protein oxidation in FABP4/aP2^-/- macrophages attenuates the mitochondrial unfolded-protein response (mtUPR) as measured by expression of heat shock protein 60, Clp protease, and Lon peptidase 1. Consistent with a diminished mtUPR, FABP4/aP2^-/- macrophages exhibit reduced expression of cleaved caspase-1 and NLRP3. Secretion of interleukin 1β (IL-1β), in response to inflammasome activation, is ablated in FABP4/aP2^-/- macrophages, as well as in FABP4/aP2 inhibitor-treated cells, but partially rescued in FABP4/aP2-null macrophages when UCP2 is silenced. Collectively, these data offer a novel pathway whereby FABP4/aP2 regulates macrophage redox signaling and inflammasome activation via control of UCP2 expression.

Diabesity and Brain Energy Metabolism: The Case of Alzheimer's Disease

It is widely accepted that high calorie diets and a sedentary lifestyle sturdily influence the incidence and outcome of type 2 diabetes and obesity, which can occur simultaneously, a situation called diabesity. Tightly linked with metabolic and energy regulation, a close association between diabetes and Alzheimer's disease (AD) has been proposed. Among the common pathogenic mechanisms that underpin both conditions, insulin resistance, brain glucose hypometabolism, and metabolic dyshomeostasis appear to have a pivotal role. This century is an unprecedented diabetogenic period in human history, so therapeutic strategies and/or approaches to control and/or revert this evolving epidemic is of utmost importance. This chapter will make a brief contextualization about the impact that diabetes and obesity can exert in brain structure and function alongside with a brief survey about the role of insulin in normal brain function, exploring its roles in cognition and brain glucose metabolism. Later, attention will be given to the intricate relation of diabesity, insulin resistance, and AD. Finally, both pharmacological and lifestyle interventions will also be reviewed as strategies aimed at fighting diabesity and/or AD-related metabolic effects.

Alzheimer's Disease: From Mitochondrial Perturbations to Mitochondrial Medicine

Age-related neurodegenerative diseases such as Alzheimer's disease (AD) are distressing conditions causing countless levels of suffering for which treatment is often insufficient or inexistent. Considered to be the most common cause of dementia and an incurable, progressive neurodegenerative disorder, the intricate pathogenic mechanisms of AD continue to be revealed and, consequently, an effective treatment needs to be developed. Among the diverse hypothesis that have been proposed to explain AD pathogenesis, the one concerning mitochondrial dysfunction has raised as one of the most discussed with an actual acceptance in the field. It posits that manipulating mitochondrial function and understanding the deficits that result in mitochondrial injury may help to control and/or limit the development of AD. To achieve such goal, the concept of mitochondrial medicine places itself as a promising gathering of strategies to directly manage the major insidious disturbances of mitochondrial homeostasis as well as attempts to directly or indirectly manage its consequences in the context of AD. The aim of this review is to summarize the evolution that occurred from the establishment of mitochondrial homeostasis perturbation as masterpieces in AD pathogenesis up until the development of mitochondrial medicine. Following a brief glimpse in the past and current hypothesis regarding the triad of aging, mitochondria and AD, this manuscript will address the major mechanisms currently believed to participate in above mentioned events. Both pharmacological and lifestyle interventions will also be reviewed as AD-related mitochondrial therapeutics.

Food Reduction in Avicenna's View and Related Principles in Classical Medicine

Context

Traditional Iranian medicine (TIM) is a rich and valuable school of thought that believes medications are not the only effective approach for the treatment of diseases but that nutrition is also important.

Evidence Acquisition

Our study includes two parts; the first is a book review of the Canon of Medicine by Avicenna (10th and 11th centuries), in which we focus on finding and understanding Avicenna’s point of view. In the second part, we searched for “food reduction” as a key word from 2000 to 2015 in databases such as Google Scholar, PubMed, Copernicus, DOAJ, EBSCO-CINAHL, and the Iranian search database Iranmedex for principles of food reduction in classical medicine.

Results

The main methods of treatment in traditional medicine include changes in lifestyle, especially diet, the use of medications, and the use of manipulation methods. For diet, the individual may be prohibited from eating or food amounts may be decreased or increased. Centuries ago, Avicenna was making use of methods of food reduction as an important therapeutic approach in the treatment of diseases. According to him, food reduction, to the extent that it does not cause energy loss helps to cure disease. Avicenna has proposed food reduction as an aid to treating a variety of ailments such as headaches and reflux.

Conclusions

Today, a variety of basic and clinical research has shown that food reduction or calorie restriction to a standard level can effectively prevent and treat a variety of diseases such as neoplasms, diabetes, and kidney disease. Practical principles explained by traditional Iranian medicine, in particular Avicenna, could open important and quite uncomplicated strategies for the prevention and treatment of diseases.

Exploring the possible link between MeCP2 and oxidative stress in Rett syndrome

Rett syndrome (RTT, MIM 312750) is a rare and orphan progressive neurodevelopmental disorder affecting girls almost exclusively, with a frequency of 1/15,000 live births of girls. The disease is characterized by a period of 6 to 18 months of apparently normal neurodevelopment, followed by early neurological regression, with a progressive loss of acquired cognitive, social, and motor skills. RTT is known to be caused in 95% of the cases by sporadic de novo loss-of-function mutations in the X-linked methyl-CpG-binding protein 2 (MECP2) gene encoding methyl-CpG binding protein 2 (MeCP2), a nuclear protein able to regulate gene expression. Despite almost two decades of research into the functions and role of MeCP2, little is known about the mechanisms leading from MECP2 mutation to the disease. Oxidative stress (OS) is involved in the pathogenic mechanisms of several neurodevelopmental and neurodegenerative disorders, although in many cases it is not clear whether OS is a cause or a consequence of the pathology. Fairly recently, the presence of a systemic OS has been demonstrated in RTT patients with a strong correlation with the patients' clinical status. The link between MECP2 mutation and the redox imbalance found in RTT is not clear. Animal studies have suggested a possible direct correlation between Mecp2 mutation and increased OS levels. In addition, the restoration of Mecp2 function in astrocytes significantly improves the developmental outcome of Mecp2-null mice and reexpression of Mecp2 gene in the brain of null mice restored oxidative damage, suggesting that Mecp2 loss of function can be involved in oxidative brain damage. Starting from the evidence that oxidative damage in the brain of Mecp2-null mice precedes the onset of symptoms, we evaluated whether, based on the current literature, the dysfunctions described in RTT could be a consequence or, in contrast, could be caused by OS. We also analyzed whether therapies that at least partially treated some RTT symptoms can play a role in defense against OS. At this stage we can propose that OS could be one of the main causes of the dysfunctions observed in RTT. In addition, the major part of the therapies recommended to alleviate RTT symptoms have been shown to interfere with oxidative homeostasis, suggesting that MeCP2 could somehow be involved in the protection of the brain from OS.

An automated task for the training and assessment of distal forelimb function in a mouse model of ischemic stroke

BACKGROUND

Behavioral models relevant to stroke research seek to capture important aspects of motor skills typically impaired in human patients, such as coordination of distal musculature. Such models may focus on mice since many genetic tools are available for use only in that species and since the training and behavioral demands of mice can differ from rats even for superficially similar behavioral readouts. However, current mouse assays are time consuming to train and score, especially in a manner producing continuous quantification. An automated assay of mouse forelimb function may provide advantages for quantification and speed, and may be useful for many applications including stroke research.

NEW METHOD

We present an automated assay of distal forelimb function. In this task, mice reach forward, grip and pull an isometric handle with a prescribed force. The apparatus partially automates the training process so that mice can be trained quickly and simultaneously.

RESULTS

Using this apparatus, it is possible to measure long-lasting impairment in success rate, force pulled, latency to pull, and latency to success up to 22 weeks following photothrombotic cortical strokes in mice.

COMPARISON WITH EXISTING METHOD(S)

This assessment measures forelimb function as do pellet reach tasks, but it utilizes a different motion and provides automatic measures that can ease and augment the research process.

CONCLUSIONS

This high-throughput behavioral assay can detect long-lasting motor impairments, eliminates the need for subjective scoring, and produces a rich, continuous data set from which many aspects of the reach and grasp motion can be automatically extracted.

Globular Adiponectin Causes Tolerance to LPS-Induced TNF-α Expression via Autophagy Induction in RAW 264.7 Macrophages: Involvement of SIRT1/FoxO3A Axis

Adiponectin, an adipokine predominantly produced from adipose tissue, exhibited potent anti-inflammatory properties. In particular, it inhibits production of pro-inflammatory cytokines, including tumor necrosis factor-α (TNF-α), in macrophages. Autophagy, an intracellular self-digestion process, has been recently shown to regulate inflammatory responses. In the present study, we investigated the role of autophagy induction in the suppression of Lipopolysaccharide (LPS) -induced TNF-α expression by globular adiponectin (gAcrp) and its potential mechanisms. Herein, we found that gAcrp treatment increased expression of genes related with autophagy, including Atg5 and microtubule-associated protein light chain (LC3B), induced autophagosome formation and autophagy flux in RAW 264.7 macrophages. Similar results were observed in primary macrophages isolated peritoneum of mice. Interestingly, inhibition of autophagy by pretreatment with Bafilomycin A1 or knocking down of LC3B gene restored suppression of TNF-α expression, tumor necrosis factor receptor- associated factor 6 (TRAF6) expression and p38MAPK phosphorylation by gAcrp, implying a critical role of autophagy induction in the development of tolerance to LPS-induced TNF-α expression by gAcrp. We also found that knocking-down of FoxO3A, a forkhead box O member of transcription factor, blocked gAcrp-induced expression of LC3II and Atg5. Moreover, gene silencing of Silent information regulator 1 (SIRT1) blocked both gAcrp-induced nuclear translocation of FoxO3A and LC3II expression. Finally, pretreatment with ROS inhibitors, prevented gAcrp-induced SIRT1 expression and further generated inhibitory effects on gAcrp-induced autophagy, indicating a role of ROS production in gAcrp-induced SIRT1 expression and subsequent autophagy induction. Taken together, these findings indicate that globular adiponectin suppresses LPS-induced TNF-α expression, at least in part, via autophagy activation. Furthermore, SIRT1-FoxO3A axis plays a crucial role in gAcrp-induced autophagy in macrophages.

The Effects of Calorie Restriction in Depression and Potential Mechanisms

Depression, also called major depressive disorder, is a neuropsychiatric disorder jeopardizing an increasing number of the population worldwide. To date, a large number of studies have devoted great attention to this problematic condition and raised several hypotheses of depression. Based on these theories, many antidepressant drugs were developed for the treatment of depression. Yet, the depressed patients are often refractory to the antidepressant therapies. Recently, increasing experimental evidences demonstrated the effects of calorie restriction in neuroendocrine system and in depression. Both basic and clinical investigations indicated that short-term calorie restriction might induce an antidepressant efficacy in depression, providing a novel avenue for treatment. Molecular basis underlying the antidepressant actions of calorie restriction might involve multiple physiological processes, primarily including orexin signaling activation, increased CREB phosphorylation and neurotrophic effects, release of endorphin and ketone production. However, the effects of chronic calorie restriction were quite controversial, in the cases that it often resulted in the long-term detrimental effects via inhibiting the function of 5-HT system and decreasing leptin levels. Here we review such dual effects of calorie restriction in depression and potential molecular basis behind these effects, especially focusing on antidepressant effects.

Intermittent fasting attenuates inflammasome activity in ischemic stroke

Recent findings have revealed a novel inflammatory mechanism that contributes to tissue injury in cerebral ischemia mediated by multi-protein complexes termed inflammasomes. Intermittent fasting (IF) can decrease the levels of pro-inflammatory cytokines in the periphery and brain. Here we investigated the impact of IF (16h of food deprivation daily) for 4months on NLRP1 and NLRP3 inflammasome activities following cerebral ischemia. Ischemic stroke was induced in C57BL/6J mice by middle cerebral artery occlusion, followed by reperfusion (I/R). IF decreased the activation of NF-κB and MAPK signaling pathways, the expression of NLRP1 and NLRP3 inflammasome proteins, and both IL-1β and IL-18 in the ischemic brain tissue. These findings demonstrate that IF can attenuate the inflammatory response and tissue damage following ischemic stroke by a mechanism involving suppression of NLRP1 and NLRP3 inflammasome activity.

Changes in mitochondrial function are pivotal in neurodegenerative and psychiatric disorders: how important is BDNF?

The brain is at the very limit of its energy supply and has evolved specific means of adapting function to energy supply, of which mitochondria form a crucial link. Neurotrophic and inflammatory processes may not only have opposite effects on neuroplasticity, but also involve opposite effects on mitochondrial oxidative phosphorylation and glycolytic processes, respectively, modulated by stress and glucocorticoids, which also have marked effects on mood. Neurodegenerative processes show marked disorders in oxidative metabolism in key brain areas, sometimes decades before symptoms appear (Parkinson's and Alzheimer's diseases). We argue that brain-derived neurotrophic factor couples activity to changes in respiratory efficiency and these effects may be opposed by inflammatory cytokines, a key factor in neurodegenerative processes.

Additive antidepressant-like effects of fasting with imipramine via modulation of 5-HT2 receptors in the mice

Recently, studies show that intermittent fasting and caloric restriction may improve symptoms of depression. However, there is little scientific evidence regarding the literature on the antidepressant-like effects of acute fasting. The present study aims to investigate the antidepressant-like effects and its influence on brain levels of the transcription factor cAMP response element-binding protein (CREB) and its phosphorylated form (p-CREB) in different time periods of fasting mice. Furthermore, the additive antidepressant-like effects of fasting with imipramine and the possible involvement of the 5-HT2 receptors were examined. In the present study 9h, but not 3h and 18h of fasting significantly reduced immobility time in the forced swimming test (FST) without alteration in locomotor activity in the open field test. 9h fasting also enhanced the ratio of p-CREB/CREB in the frontal cortex and hippocampus. Co-administration of 9h of fasting and imipramine (30mg/kg, i.p) produced the additive antidepressant-like effects in the FST and increased the ratio of p-CREB/CREB. Meanwhile, the additive effects were partially reversed by treatment with a 5-HT2A/2C receptor agonist, (±)-1-(2, 5-dimethoxy-4-iodophenyl)-2-aminopropane hydrochloride (DOI) (5mg/kg, s.c). Furthermore, the antidepressant-like effects of 9h fasting was also blocked by DOI compared to the non-fasting control group. Serum corticosterone level, but not 5-HT and noradrenaline, was significantly increased in a time-dependent manner following different time periods of fasting. Taken together, these results suggest that acute fasting produces antidepressant-like effects via enhancement of the p-CREB/CREB ratio, and additive antidepressant-like effects of fasting with imipramine may be related to modulating 5-HT2 receptors.

Preclinical models of stroke in aged animals with or without comorbidities: role of neuroinflammation

Age is the principal nonmodifiable risk factor for stroke. Over the past 10 years, suitable models for stroke in aged rats have been established. At genetic and cellular level there are significant differences in behavioral, cytological and genomics responses to injury in old animals as compared with the young ones. Behaviorally, the aged rats have the capacity to recover after cortical infarcts albeit to a lower extent than the younger counterparts. Similarly, the increased vulnerability of the aged brain to stroke, together with a decreased interhemisphere synchrony after stroke, assessed by different experimental methods (MRI, fMRI, in vivo microscopy, EEG) leads to unfavorable recovery of physical and cognitive functions in aged people and may have a prognostic value for the recovery of stroke patients. Furthermore, in elderly, comorbidities like diabetes or arterial hypertension are associated with higher risk of stroke, increased mortality and disability, and poorer functional status and quality of life. Aging brain reacts strongly to ischemia-reperfusion injury with an early inflammatory response. The process of cellular senescence can be an important additional contributor to chronic post-stroke by creating a "primed" inflammatory environment in the brain. Overall, these pro-inflammatory reactions promote early scar formation associated with tissue fibrosis and reduce functional recovery. A better understanding of molecular factors and signaling pathways underlying the contribution of comorbidities to stroke-induced pathological sequelae, may be translated into successful treatment or prevention therapies for age-associated diseases which would improve lifespan and quality of life.

The effect of calorie restriction on acute ethanol-induced oxidative and nitrosative liver injury in rats

The aim of our study was to examine the effect of calorie restriction (CR) on oxidative and nitrosative liver injury in rats, induced by acute ethanol intoxication. Male Wistar rats were divided into groups: (1) control; (2) calorie-restricted groups with intake of 60-70% (CR60-70) and 40-50% of daily energy needs (CR40-50); (3) ethanol-treated group (E); (4) calorie-restricted, ethanol-treated groups (E+CR60-70 and E+CR40-50). Ethanol was administered in 5 doses of 2g/kg every 12h, and duration of CR was 5 weeks before ethanol treatment. Malondialdehyde and nitrite and nitrate level were significantly lower in E+CR60-70 and higher in E+CR40-50 vs. E group. Liver reduced glutathione content and activity of both superoxide dismutase izoenzymes were significantly higher in E+CR60-70 and lower in E+CR40-50 vs. E group. Oxidative stress may be a potential mechanism of hormetic effects of CR on acute ethanol-induced liver injury.

Brain response to calorie restriction

Calorie restriction extends longevity and delays ageing in model organisms and mammals, opposing the onset and progression of an array of age-related diseases. These beneficial effects also extend to the maintenance of brain cognitive functions at later age and to the prevention, at least in rodents, of brain senescence and associated neurodegenerative disorders. In recent years, the molecular mechanisms underlying brain response to calorie restriction have begun to be elucidated, revealing the unanticipated role of a number of key nutrient sensors and nutrient-triggered signaling cascades in the translation of metabolic cues into cellular and molecular events that ultimately lead to increased cell resistance to stress, enhanced synaptic plasticity, and improved cognitive performance. Of note, the brain's role in CR also includes the activation of nutrient-sensitive hypothalamic circuitries and the implementation of neuroendocrine responses that impact the entire organism. The present review addresses emerging molecular themes in brain response to dietary restriction, and the implications of this knowledge for the understanding and the prevention of brain disorders associated with ageing and metabolic disease.

Involvement of arterial baroreflex in the protective effect of dietary restriction against stroke

Dietary restriction (DR) protects against neuronal dysfunction and degeneration, and reduces the risk of ischemic stroke. This study examined the role of silent information regulator T1 (SIRT1) and arterial baroreflex in the beneficial effects of DR against stroke, using two distinct stroke models: stroke-prone spontaneously hypertensive rats (SP-SHRs) and Sprague-Dawley (SD) rats with middle cerebral artery occlusion (MCAO). Sirt1 knockout (KO) mice were used to examine the involvement of sirt1. Sinoaortic denervation was used to inactivate arterial baroreflex. Dietary restriction was defined as 40% reduction of dietary intake. Briefly, DR prolonged the life span of SP-SHRs and reduced the infarct size induced by MCAO. Dietary restriction also improved the function arterial baroreflex, decreased the release of proinflammatory cytokines, and reduced end-organ damage. The beneficial effect of DR on stroke was markedly attenuated by blunting arterial baroreflex. Lastly, the infarct area in sirt1 KO mice was significantly larger than in the wild-type mice. However, the beneficial effect of DR against ischemic injury was still apparent in sirt1 KO mice. Accordingly, arterial baroreflex, but not sirt1, is important in the protective effect of DR against stroke.

Role of the hypothalamus in mediating protective effects of dietary restriction during aging

Dietary restriction (DR) can extend lifespan and reduce disease burden across a wide range of animals and yeast but the mechanisms mediating these remarkably protective effects remain to be elucidated despite extensive efforts. Although it has generally been assumed that protective effects of DR are cell-autonomous, there is considerable evidence that many whole-body responses to nutritional state, including DR, are regulated by nutrient-sensing neurons. In this review, we explore the hypothesis that nutrient sensing neurons in the ventromedial hypothalamus hierarchically regulate the protective responses of dietary restriction. We describe multiple peripheral responses that are hierarchically regulated by the hypothalamus and we present evidence for non-cell autonomous signaling of dietary restriction gathered from a diverse range of models including invertebrates, mammalian cell culture, and rodent studies.

Sarcopenia, a neurogenic syndrome?

Sarcopenia is an aging-associated condition, which is currently characterized by the loss of muscle mass and muscle strength. However, there is no consensus regarding its characterization hitherto. As the world older adult population is on the rise, the impact of sarcopenia becomes greater. Due to the lack of effective treatments, sarcopenia is still a persisting problem among the global older adults and should not be overlooked. As a result, it is vital to investigate deeper into the mechanism underlying the pathogenesis of sarcopenia in order to develop more effective therapeutic interventions and to inscribe a more uniform characterization. The etiology of sarcopenia is currently found to be multifactorial, and most of the pharmacological researches are focused on the muscular factors in aging. Although the complete mechanism underlying the development of sarcopenia is still waiting to be elucidated, we propose in this article that the primary trigger of sarcopenia may be neurogenic in origin based on the intimate relationship between the nervous and muscular system, namely, the motor neuron and its underlying muscle fibers. Both of them are affected by the cellular environment and their physiological activity.

Stroke outcome in the ketogenic state--a systematic review of the animal data

As a predictor of potential clinical outcome, we performed a systematic review of controlled studies that assessed experimental stroke outcome in rodents maintained on special diets (calorie restriction and ketogenic diet) or following the direct administration of ketone bodies. Pre-clinical studies were identified by searching web databases and the reference lists of relevant original articles and reviews. Sixteen published studies (a total of 733 experimental animals) met specific criteria and were analyzed using Cochrane Review Manager software. This resulted in objective evidence to suggest beneficial effects of the ketogenic pathway on pathological and functional outcomes following experimental stroke.

Caloric restriction suppresses microglial activation and prevents neuroapoptosis following cortical injury in rats

Traumatic brain injury (TBI) is a widespread cause of death and a major source of adult disability. Subsequent pathological events occurring in the brain after TBI, referred to as secondary injury, continue to damage surrounding tissue resulting in substantial neuronal loss. One of the hallmarks of the secondary injury process is microglial activation resulting in increased cytokine production. Notwithstanding that recent studies demonstrated that caloric restriction (CR) lasting several months prior to an acute TBI exhibits neuroprotective properties, understanding how exactly CR influences secondary injury is still unclear. The goal of the present study was to examine whether CR (50% of daily food intake for 3 months) alleviates the effects of secondary injury on neuronal loss following cortical stab injury (CSI). To this end, we examined the effects of CR on the microglial activation, tumor necrosis factor-α (TNF-α) and caspase-3 expression in the ipsilateral (injured) cortex of the adult rats during the recovery period (from 2 to 28 days) after injury. Our results demonstrate that CR prior to CSI suppresses microglial activation, induction of TNF-α and caspase-3, as well as neurodegeneration following injury. These results indicate that CR strongly attenuates the effects of secondary injury, thus suggesting that CR may increase the successful outcome following TBI.

C5a receptor (CD88) inhibition improves hypothermia-induced neuroprotection in an in vitro ischemic model

The concept of 'salvageble penumbra' has prompted both scientists and physicians to explore various neuroprotective approaches that could be beneficial during stroke therapy. Unfortunately, most of them have proved ineffective in targeting multiple cellular death cascades incited within the ischemic penumbra. Hypothermia has been shown to be capable of addressing this problem to some extent. Although many studies have shown that hypothermia targets several cellular processes, its effects on innate immune receptor-mediated apoptotic death still remain unclear. Moreover, whether inhibiting the signaling of innate immune receptors like complement anaphylatoxin C5a receptor (CD88) plays a role in this hypothermic neuroprotection still need to be deciphered. Using various types of ischemic insults in different neuronal cells, we confirm that hypothermia does indeed attenuate apoptotic neuronal cell death in vitro and this effect can be further enhanced by pharmacologically blocking or knocking out CD88. Thus, our study raises a promising therapeutic possibility of adding CD88 antagonists along with hypothermia to improve stroke outcomes.

Neuroprotection by dietary restriction and the PPAR transcription complex

Although the pathophysiology of neurodegenerative diseases is distinct for each disease, considerable evidence suggests that a single manipulation, dietary restriction, is strikingly protective against a wide range of such diseases. Thus pharmacological mimetics of dietary restrictions could prove widely protective across a range of neurodegenerative diseases. The PPAR transcription complex functions to re-program gene expression in response to nutritional deprivation as well as in response to a wide variety of lipophilic compounds. In mammals there are three PPAR homologs, which dimerize with RXR homologs and recruit coactivators Pgc1-alpha and Creb-binding protein (Cbp). PPARs are currently of clinical interest mainly because PPAR activators are approved for use in humans to reduce lipidemia and to improve glucose control in Type 2 diabetic patients. However, pharmacological enhancement of the activity of the PPAR complex is neuroprotective across a wide variety of models for neuropathological processes, including stroke, Alzheimer’s disease, Parkinson’s disease, and Huntington’s disease. Conversely activity of the PPAR transcriptional complex is reduced in a variety of neuropathological processes. The main mechanisms mediating the neuroprotective effects of the PPAR transcription complex appear to be re-routing metabolism away from glucose metabolism and toward alternative subtrates, and reduction in inflammatory processes. Recent evidence suggests that the PPAR transcriptional complex may also mediate protective effects of dietary restriction on neuropathological processes. Thus this complex represents one of the most promising for the development of pharmacological treatment of neurodegenerative diseases.