Obesity, leptin, and Alzheimer's disease

Impaired Remodeling of White Adipose Tissue in Obesity and Aging: From Defective Adipogenesis to Adipose Organ Dysfunction

The adipose organ adapts and responds to internal and environmental stimuli by remodeling both its cellular and extracellular components. Under conditions of energy surplus, the subcutaneous white adipose tissue (WAT) is capable of expanding through the enlargement of existing adipocytes (hypertrophy), followed by de novo adipogenesis (hyperplasia), which is impaired in hypertrophic obesity. However, an impaired hyperplastic response may result from various defects in adipogenesis, leading to different WAT features and metabolic consequences, as discussed here by reviewing the results of the studies in animal models with either overexpression or knockdown of the main molecular regulators of the two steps of the adipogenesis process. Moreover, impaired WAT remodeling with aging has been associated with various age-related conditions and reduced lifespan expectancy. Here, we delve into the latest advancements in comprehending the molecular and cellular processes underlying age-related changes in WAT function, their involvement in common aging pathologies, and their potential as therapeutic targets to influence both the health of elderly people and longevity. Overall, this review aims to encourage research on the mechanisms of WAT maladaptation common to conditions of both excessive and insufficient fat tissue. The goal is to devise adipocyte-targeted therapies that are effective against both obesity- and age-related disorders.

The Levels of Leptin, Cystatin C, Neuropilin-1 and Tau Protein in Relation to Dietary Habits in Patients with Alzheimer's Disease

Alzheimer's disease (AD) is the most common form of dementia in older people. Its prevalence is expected to increase, and therefore it poses a serious challenge to the healthcare system. The aim of the study was to assess the concentration of leptin, cystatin C, neuropilin-1 and tau protein, as well as the influence of dietary habits on these parameters, in a group of AD patients (n = 110) compared to 60 healthy people (n = 60). It has been shown that AD patients, compared to healthy people, are characterized by significantly higher median concentrations of leptin (9.97 vs. 3.08), cystatin c (1.53 vs. 0.56) and tau protein (8.46 vs. 4.19), but significantly lower median neuropilin-1 (69.94 vs. 167.28). Multiple regression analyses showed that leptin levels could be explained by dietary habits in 27%, cystatin C in 51%, neuropilin-1 in 41% and tau protein in 25% of cases. Modification of eating habits may contribute to improving the values of the discussed parameters.

Recent Development in the Understanding of Molecular and Cellular Mechanisms Underlying the Etiopathogenesis of Alzheimer's Disease

Alzheimer's disease (AD) is a progressive neurodegenerative disorder that leads to dementia and patient death. AD is characterized by intracellular neurofibrillary tangles, extracellular amyloid beta (Aβ) plaque deposition, and neurodegeneration. Diverse alterations have been associated with AD progression, including genetic mutations, neuroinflammation, blood-brain barrier (BBB) impairment, mitochondrial dysfunction, oxidative stress, and metal ion imbalance.Additionally, recent studies have shown an association between altered heme metabolism and AD. Unfortunately, decades of research and drug development have not produced any effective treatments for AD. Therefore, understanding the cellular and molecular mechanisms underlying AD pathology and identifying potential therapeutic targets are crucial for AD drug development. This review discusses the most common alterations associated with AD and promising therapeutic targets for AD drug discovery. Furthermore, it highlights the role of heme in AD development and summarizes mathematical models of AD, including a stochastic mathematical model of AD and mathematical models of the effect of Aβ on AD. We also summarize the potential treatment strategies that these models can offer in clinical trials.

Brown adipose tissue and alzheimer's disease

Alzheimer's disease (AD), the most common type of senile dementia, is a chronic neurodegenerative disease characterized by cognitive dysfunction and behavioral disability. The two histopathological hallmarks in this disease are the extraneuronal accumulation of amyloid-β (Aβ) and the intraneuronal deposition of neurofibrillary tangles (NFTs). Despite this, central and peripheral metabolic dysfunction, such as abnormal brain signaling, insulin resistance, inflammation, and impaired glucose utilization, have been indicated to be correlated with AD. There is solid evidence that the age-associated thermoregulatory deficit induces diverse metabolic changes associated with AD development. Brown adipose tissue (BAT) has been known as a thermoregulatory organ particularly vital during infancy. However, in recent years, BAT has been accepted as an endocrine organ, being involved in various functions that prevent AD, such as regulating energy metabolism, secreting hormones, improving insulin sensitivity, and increasing glucose utilization in adult humans. This review focuses on the mechanisms of BAT activation and the effect of aging on BAT production and signaling. Specifically, the evidence demonstrating the effect of BAT on pathological mechanisms influencing the development of AD, including insulin pathway, thermoregulation, and other hormonal pathways, are reviewed in this article.

Association of cognition with leptin and vascular endothelial growth factor in individuals with type 2 diabetes mellitus

OBJECTIVE

The 10-year intensive lifestyle intervention (ILI) of the Look AHEAD study left a legacy of relative deficits in cognitive function among participants who entered the clinical trial with obesity or a history of cardiovascular disease. We hypothesized that altered levels of two weight-sensitive proangiogenic cytokines, leptin and vascular endothelial growth factor (VEGF), accounted for this concerning finding.

METHODS

Serum leptin and VEGF concentrations were determined in 1,279 Look AHEAD participants at baseline, proximal to cessation of the interventions (Epoch 1), and an average of 4 years later (Epoch 2). Up to four standardized assessments of attention, executive function, and memory were collected during follow-up. Mixed effects models were used to assess relative differences in leptin and VEGF concentrations between intervention groups and whether these accounted for changes in cognitive composite scores.

RESULTS

ILI and diabetes support and education differences in VEGF, but not leptin, concentrations varied depending on baseline history of cardiovascular disease and obesity, but neither leptin nor VEGF concentrations accounted for the relative decrements in cognitive function in participants assigned to ILI.

CONCLUSIONS

Alterations in two weight-sensitive proangiogenic cytokines did not account for the long-term adverse effects of ILI on cognitive function among adults with diabetes and either obesity or cardiovascular disease.

Pathogenesis, Murine Models, and Clinical Implications of Metabolically Healthy Obesity

Although obesity is commonly associated with numerous cardiometabolic pathologies, some people with obesity are resistant to detrimental effects of excess body fat, which constitutes a condition called “metabolically healthy obesity” (MHO). Metabolic features of MHO that distinguish it from metabolically unhealthy obesity (MUO) include differences in the fat distribution, adipokine types, and levels of chronic inflammation. Murine models are available that mimic the phenotype of human MHO, with increased adiposity but preserved insulin sensitivity. Clinically, there is no established definition of MHO yet. Despite the lack of a uniform definition, most studies describe MHO as a particular case of obesity with no or only one metabolic syndrome components and lower levels of insulin resistance or inflammatory markers. Another clinical viewpoint is the dynamic and changing nature of MHO, which substantially impacts the clinical outcome. In this review, we explore the pathophysiology and some murine models of MHO. The definition, variability, and clinical implications of the MHO phenotype are also discussed. Understanding the characteristics that differentiate people with MHO from those with MUO can lead to new insights into the mechanisms behind obesity-related metabolic derangements and diseases.

The influence of gastric bypass surgery on the concentration of high mobility group box 1, nuclear factor erythroid 2-related factor 2 and the genes expression of high mobility group box 1, nuclear factor erythroid2-related factor 2, interleukin 6, and tumor necrosis factor-alpha in the peripheral blood mononuclear cells of patients with morbid obesity

BACKGROUND AND OBJECTIVES

Obesity is known as a disease with a chronic low-grade state of inflammation and high levels of oxidative stress. Given the challenges and consequences caused by obesity, obesity therapy is an essential subject to address. For sustainable weight loss, gastric bypass surgery is the most successful and essential option.

METHODS

This prospective cohort study was performed on 35 patients aged (18-54) with morbid obesity (BMI: 42.06 kg/m²). Volunteers blood was taken, and peripheral blood mononuclear cells (PBMCs) were isolated, high mobility group box 1(HMGB1), nuclear factor erythroid2-related factor 2(Nrf2), Interleukin 6(IL-6), tumor necrosis factor-alpha (TNF-α), and biochemical factors were determined one day before and 4 months after surgery.

RESULTS

Four months following surgery, the BMI, hip and waist circumferences, and waist-to-hip ratio (WHR) all decreased significantly. The lipid profile and antioxidant power were dramatically enhanced after surgery. IL-6 and TNF-α expression in PBMC patients showed a significant decrease after surgery. HMGB1 and Nrf2 expression in PBMC of postoperative patients decreased compared to before surgery, and HMGB1, and Nrf2 protein levels also decreased after surgery.

CONCLUSION

Weight loss indicated the significant function of adipose tissue in the induction of oxidative stress and inflammatory factors. Gastric bypass reduced the inflammation conditions and improved the metabolic status and living situations in the patients with morbid obesity.

Nanocarrier mediated drug delivery as an impeccable therapeutic approach against Alzheimer's disease

For the past several years, dementia, is one of the predominantly observed groups of symptoms in a geriatric population. Alzheimer's disease (AD) is a progressive memory related neurodegenerative disease, for which the current Food and drug administration approved therapeutics are only meant for a symptomatic management rather than targeting the root cause of AD. These therapeutics belong to two classes, Acetylcholine Esterase inhibitors and N-methyl D-aspartate antagonist. Furthermore, to facilitate neuroprotective action in AD, the drugs are majorly expected to reach the specific target area in the brain for the desired efficacy. Thus, there is a huge requirement for drug discovery and development for facilitating the entry of drugs more in brain to exert a specific action. The very first line of defense and the major limitation for the entry of drugs into the brain is the Blood Brain Barrier, followed by Blood-Cerebrospinal Fluid Barrier. More than a barrier, these mainly act as selectively permeable membranes, which allows entry of specific molecules into the brain. Furthermore, specific enzymes result in the degradation of xenobiotics. All these mechanisms pose as hurdles in the way of effective drug delivery in the brain. Thus, novel techniques need to be harbored for the facilitation of the delivery of such drugs into the brain. Nanocarriers are advantageous for facilitating the specific targeted drug treatment in AD. As nanomedicines are one of the novels and most useful approaches for AD, thus the present review mainly focuses on understanding the advanced use of nanocarriers for targeted drug delivery in the management of AD.

Common pathways in dementia and diabetic retinopathy: understanding the mechanisms of diabetes-related cognitive decline

Type 2 diabetes (T2D) is associated with multiple comorbidities, including diabetic retinopathy (DR) and cognitive decline, and T2D patients have a significantly higher risk of developing Alzheimer's disease (AD). Both DR and AD are characterized by a number of pathological mechanisms that coalesce around the neurovascular unit, including neuroinflammation and degeneration, vascular degeneration, and glial activation. Chronic hyperglycemia and insulin resistance also play a significant role, leading to activation of pathological mechanisms such as increased oxidative stress and the accumulation of advanced glycation end-products (AGEs). Understanding these common pathways and the degree to which they occur simultaneously in the brain and retina during diabetes will provide avenues to identify T2D patients at risk of cognitive decline.

Cardiometabolic Modification of Amyloid Beta in Alzheimer's Disease Pathology

In recent years, several studies have suggested that cardiometabolic disorders, such as diabetes, obesity, hypertension, and dyslipidemia, share strong connections with the onset of neurodegenerative disorders such as Parkinson’s and Alzheimer’s disease (AD). However, establishing a definitive link between medical disorders with coincident pathophysiologies is difficult due to etiological heterogeneity and underlying comorbidities. For this reason, amyloid β (Aβ), a physiological peptide derived from the sequential proteolysis of amyloid precursor protein (APP), serves as a crucial link that bridges the gap between cardiometabolic and neurodegenerative disorders. Aβ normally regulates neuronal synaptic function and repair; however, the intracellular accumulation of Aβ within the brain has been observed to play a critical role in AD pathology. A portion of Aβ is believed to originate from the brain itself and can readily cross the blood-brain barrier, while the rest resides in peripheral tissues that express APP required for Aβ generation such as the liver, pancreas, kidney, spleen, skin, and lungs. Consequently, numerous organs contribute to the body pool of total circulating Aβ, which can accumulate in the brain and facilitate neurodegeneration. Although the accumulation of Aβ corresponds with the onset of neurodegenerative disorders, the direct function of periphery born Aβ in AD pathophysiology is currently unknown. This review will highlight the contributions of individual cardiometabolic diseases including cardiovascular disease (CVD), type 2 diabetes (T2D), obesity, and non-alcoholic fatty liver disease (NAFLD) in elevating concentrations of circulating Aβ within the brain, as well as discuss the comorbid association of Aβ with AD pathology.

Differential effects of body mass index on domain-specific cognitive outcomes after stroke

Although the obesity paradox is an important modifiable factor in cardiovascular diseases, little research has been conducted to determine how it affects post-stroke cognitive function. We aimed to investigate the association between body mass index (BMI) and domain-specific cognitive outcomes, focusing on the subdivision of each frontal domain function in post-ischemic stroke survivors. A total of 335 ischemic stroke patients were included in the study after completion of the Korean-Mini Mental Status Examination (K-MMSE) and the vascular cognitive impairment harmonization standards neuropsychological protocol at 3 months after stroke. Frontal lobe functions were analyzed using semantic/phonemic fluency, processing speed, and mental set shifting. Our study participants were categorized into four groups according to BMI quartiles. The z-scores of K-MMSE at 3 months differed significantly between the groups after adjustment for initial stroke severity (p = 0.014). Global cognitive function in stroke survivors in the Q1 (the lowest quartile) BMI group was significantly lower than those in Q2 and Q4 (the highest quartile) BMI groups (K-MMSE z-scores, Q1: − 2.10 ± 3.40 vs. Q2: 0.71 ± 1.95 and Q4: − 1.21 ± 1.65). Controlled oral word association test findings indicated that phonemic and semantic word fluency was lower in Q4 BMI group participants than in Q2 BMI group participants (p = 0.016 and p = 0.023 respectively). BMI might differentially affect cognitive domains after ischemic stroke. Although being underweight may negatively affect global cognition post-stroke, obesity could induce frontal lobe dysfunctions, specifically phonemic and semantic word fluency.

The risk of Alzheimer's disease according to dynamic changes in metabolic health and obesity: a nationwide population-based cohort study

We evaluated the association of metabolic health and obesity phenotypes with the risk of Alzheimer's disease (AD). This study enrolled 136,847 elderly participants aged 60 or above from the Korean National Health Insurance System. At baseline examinations in 2009 and 2010, subjects were categorized into four groups: the metabolically healthy non-obese (MHNO), metabolically healthy obese (MHO), metabolically unhealthy non-obese (MUNO), and metabolically unhealthy obese (MUO) groups. Based on the phenotypic transition after 2 years, the subjects were further categorized into 16 subgroups. They were followed from 2009 to 2015 to monitor for AD development. The MHO phenotype protected subjects from AD, relative to the MHNO phenotype (HR, 0.73; 95% CI, 0.65-0.81). Among subjects initially classified as MHO, 41.8% remained MHO, with a significantly lower risk of AD compared with the stable MHNO group (HR, 0.62; 95% CI, 0.50-0.77). Among MUO subjects at baseline, those who changed phenotype to MUNO were at higher risk of AD (HR, 1.47; 95% CI, 1.28-1.70), and the transition to the MHO phenotype protected subjects from AD (HR, 0.62; 95% CI, 0.50-0.78). The MHO phenotype conferred a decreased risk of AD. Maintenance or recovery of metabolic health might mitigate AD risk among obese individuals.

Association of dyslipidaemia with Alzheimer's disease in a cohort of postmenopausal women

Objective

To evaluate the association between dyslipidaemia and Alzheimer’s disease (AD) in a cohort of postmenopausal women.

Methods

This retrospective study analysed data from postmenopausal women with early AD (group AD) and a cohort of healthy age- and sex-matched control subjects (group NC) that were considered to be within standard limits according to a neuropsychological assessment between March 2010 and March 2019. The primary endpoints were body mass index and lipid-related laboratory parameters, including leptin, high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), total cholesterol, adiponectin, triglycerides, apolipoprotein A1, apolipoprotein B and apolipoprotein E4, which were evaluated using multivariate binary logistic analysis.

Results

The study enrolled 200 postmenopausal women with early AD (mean ± SD age 69.34 ± 6.25 years) and 180 control subjects (mean ± SD age 67.48 ± 7.42 years). Lower HDL-C and higher LDL-C were risk factors for AD. A multivariate binary logistic regression model demonstrated that lower HDL-C and higher LDL-C were the only variables associated with the development of AD (odds ratio [OR] 21.14, 95% confidence interval [CI] 2.47, 4.13; OR 36.35, 95% CI 1.24, 3.38; respectively).

Conclusion

Both low HDL-C and high LDL-C were associated with the occurrence of AD in a cohort of postmenopausal women.

Metabolically healthy obesity and lipids may be protective factors for pathological changes of alzheimer's disease in cognitively normal adults

The associations between obesity and Alzheimer's disease (AD) at different ages have been debated. Recent evidence implied the protective effects of metabolically healthy obesity on AD. We hypothesized that obesity and lipids could mitigate the detrimental impacts of AD pathological changes among metabolically healthy individuals in late life. In this study, a total of 604 metabolically healthy participants with normal cognition were included from the Chinese Alzheimer's Biomarker and LifestylE (CABLE) database. Multiple linear regression models were used to test the associations of body mass index (BMI) or lipids with cerebrospinal fluid (CSF) biomarkers after adjustment for age, gender, education, and Apolipoprotein E-ɛ4 (APOE-ɛ4). The results showed the lower CSF levels of total tau protein (t-tau: p = .0048) and phosphorylated tau protein (p-tau: p = .0035) in obese participants than in non-obese participants, even after correcting for covariates. Moreover in late life, higher BMI was associated with decreased CSF t-tau (β: -0.15, p = .0145) and p-tau (β: -0.17, p = .0052). As for lipids, higher levels of total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C) were associated with decreased CSF t-tau (TC: β: -0.16, p = .0115; LDL-C: β: -0.16, p = .0082) and p-tau (TC: β: -0.15, p = .0177; LDL-C: β: -0.14, p = .0225) in obese participants. Furthermore, these associations were only significant in participants with late-life obesity and APOE-ɛ4 non-carriers. Overall, in a cognitively normal population, we found metabolically healthy obesity and lipids in late life might be protective factors for neurodegenerative changes.

Associations Between Obesity and Alzheimer's Disease: Multiple Bioinformatic Analyses

BACKGROUND

Identifying modifiable risk factors, such as obesity, to lower the prevalence of Alzheimer's disease (AD) has gained much interest. However, whether the association is causal remains to be evaluated.

OBJECTIVE

The present study was designed: 1) to make a quantitative assessment of the association between obesity and AD; 2) to validate whether there was a causal association between them; and 3) to provide genetic clues for the association through a network-based analysis.

METHODS

Two-sample Mendelian randomization (2SMR) analysis, meta-analysis, and protein-protein interaction (PPI) network analysis, were employed.

RESULTS

Firstly, the meta-analysis based on 9 studies comprising 6,986,436 subjects indicated that midlife obesity had 33%higher AD odds than controls (OR = 1.33, 95%CI = [1.03, 1.62]), while late-life obesity were inversely associated with AD risk (OR = 0.57, 95%CI = [0.47, 0.68]). Secondly, 2SMR analysis indicated that there was no causal association between them. Thirdly, CARTPT was identified to be shared by the anti-obesity drug targets and AD susceptibility genes. Further PPI network analysis found that CARTPT interacted with CD33, a strong genetic locus linked to AD. Finally, 2SMR analysis showed that CNR1 could be a protective factor for AD.

CONCLUSION

Multiple bioinformatic analyses indicated that midlife obesity might increase the risk of AD, while current evidence indicated that there was no causal association between them. Further, CARTPT might be an important factor linking the two disease conditions. It could help to better understand the mechanisms underlying the associations between obesity and AD.

Circadian changes in Alzheimer's disease: Neurobiology, clinical problems, and therapeutic opportunities

The understanding of Alzheimer's disease (AD) pathophysiology is an active area of research, and the traditional focus on hippocampus, amyloid and tau protein, and memory impairment has been expanded with components like neuroinflammation, insulin resistance, and circadian rhythm alterations. The bidirectional vicious cycle of neuroinflammation and neurodegeneration on a molecular level may cause functional deficits already long before the appearance of overt clinical symptoms. Located at the crossroads of metabolic, circadian, and hormonal signaling, the hypothalamus has been identified as another brain region affected by AD pathophysiology. Current findings on hypothalamic dysfunction open a broader horizon for studying AD pathogenesis and offer new opportunities for diagnosis and therapy. While treatments with cholinomimetics and memantine form a first line of pharmacological treatment, additional innovative research is pursued toward the development of antiinflammatory, growth factor, or antidiabetic types of medication. Following recent epidemiological data showing associations of AD incidence with modern societal and "life-style"-related risk factors, also nonpharmacological interventions, including sleep optimization, are being developed and some have been shown to be beneficial. Circadian aspects in AD are relevant from a pathophysiological standpoint, but they can also have an important role in pharmacologic and nonpharmacologic interventions, and appropriate timing of sleep, meals, and medication may boost therapeutic efficacy.

Plasma Leptin Reflects Progression of Neurofibrillary Pathology in Animal Model of Tauopathy

The close relationship between Alzheimer's disease (AD) and obesity was recognized many years ago. However, complete understanding of the pathological mechanisms underlying the interactions between degeneration of CNS and fat metabolism is still missing. The leptin a key adipokine of white adipose tissue has been suggested as one of the major mediators linking the obesity and AD. Here we investigated the association between peripheral levels of leptin, general metabolic status and stage of the pathogenesis in rat transgenic model of AD. We demonstrate significantly decreased levels of plasma leptin in animals with experimentally induced progressive neurofibrillary pathology, which represents only 62.3% (P = 0.0015) of those observed in normal wild type control animals. More detailed analysis showed a strong and statistically significant inverse correlation between the load of neurofibrillary pathology and peripheral levels of leptin (r = - 0.7248, P = 0.0177). We also observed a loss of body weight during development of neurodegeneration (about 14% less than control animals, P = 0.0004) and decrease in several metabolic parameters such as glucose, insulin, triglycerides and VLDL in plasma of the transgenic animals. Our data suggest that plasma leptin could serve as a convenient peripheral biomarker for tauopathies and Alzheimer's disease. Decrease in gene expression of leptin in fat tissue and its plasma level was found as one of the consequences of experimentally induced neurodegeneration. Our data may help to design rational diagnostic and therapeutic strategies for patients suffering from Alzheimer's disease or other forms of tauopathy.

Adiponectin: The Potential Regulator and Therapeutic Target of Obesity and Alzheimer's Disease

Animal and human mechanistic studies have consistently shown an association between obesity and Alzheimer’s disease (AD). AD, a degenerative brain disease, is the most common cause of dementia and is characterized by the presence of extracellular amyloid beta (Aβ) plaques and intracellular neurofibrillary tangles disposition. Some studies have recently demonstrated that Aβ and tau cannot fully explain the pathophysiological development of AD and that metabolic disease factors, such as insulin, adiponectin, and antioxidants, are important for the sporadic onset of nongenetic AD. Obesity prevention and treatment can be an efficacious and safe approach to AD prevention. Adiponectin is a benign adipokine that sensitizes the insulin receptor signaling pathway and suppresses inflammation. It has been shown to be inversely correlated with adipose tissue dysfunction and may enhance the risk of AD because a range of neuroprotection adiponectin mechanisms is related to AD pathology alleviation. In this study, we summarize the recent progress that addresses the beneficial effects and potential mechanisms of adiponectin in AD. Furthermore, we review recent studies on the diverse medications of adiponectin that could possibly be related to AD treatment, with a focus on their association with adiponectin. A better understanding of the neuroprotection roles of adiponectin will help clarify the precise underlying mechanism of AD development and progression.

Neuroinflammation: An overview of neurodegenerative and metabolic diseases and of biotechnological studies

Neuroinflammation is an important factor contributing to cognitive impairment and neurodegenerative diseases, including Alzheimer's disease (AD), Parkinson's disease (PD), Amyotrophic lateral sclerosis (ALS), ischemic injury, and multiple sclerosis (MS). These diseases are characterized by inexorable progressive injury of neuron cells, and loss of motor or cognitive functions. Microglia, which are the resident macrophages in the brain, play an important role in both physiological and pathological conditions. In this review, we provide an updated discussion on the role of ROS and metabolic disease in the pathological mechanisms of activation of the microglial cells and release of cytotoxins, leading to the neurodegenerative process. In addition, we also discuss in vivo models, such as zebrafish and Caenorhabditis elegans, and provide new insights into therapeutics bioinspired by neuropeptides from venomous animals, supporting high throughput drug screening in the near future, searching for a complementary approach to elucidating crucial mechanisms associated with neurodegenerative disorders.

Relationship Between Psychological Distress and Cognitive Function Differs as a Function of Obesity Status in Inpatient Heart Failure

Heart failure (HF) is a chronic medical condition rapidly growing in prevalence. Evidence links HF to cognitive decline, obesity, and psychological distress. The current study examined the association between cognitive function and ejection fraction (EF%), anxiety, depression, and obesity in inpatient HF. Patients completed the Generalized Anxiety Disorder 7-Item Scale (GAD-7), Patient Health Questionnaire 9-Item Scale (PHQ-9), and Mini-Cog while hospitalized for HF. Additional demographic and medical information was gathered via chart review. All models controlled for age. Of 117 patients assessed (49% male), 55% (n = 64) were obese. ANCOVA analyses were conducted comparing those with obesity and without on cognitive function: model A included EF%, model B included depression, and model C included anxiety. All three models were significantly related to cognitive function. There was a significant interaction effect of EF% and obesity and of anxiety and obesity to predict Mini-Cog scores. Post hoc partial correlational analyses revealed that anxiety was negatively associated with Mini-Cog scores among only patients without obesity. Depression was not significantly related to cognitive function in either group. However, patients with obesity demonstrated higher depression and anxiety than patients without. Results suggest that at lower EF%, and with higher anxiety, patients without obesity may be at greater risk of cognitive dysfunction than those with obesity. Cognitive dysfunction among HF patients with obesity may be independent of psychological distress. These findings may reflect the “obesity paradox” observed among HF patients, in that patients with obesity may have a different biopsychosocial presentation, which may lead to unexpected clinical outcomes. Further research is necessary to articulate the relationship of obesity and cognitive function in HF.

Metabolically healthy obesity reduces the risk of Alzheimer's disease in elders: a longitudinal study

A subgroup of overweight/obese individuals, who had favorable metabolic profiles, was termed as metabolically healthy overweight/obese (MHO). Several studies suggested that MHO individuals were not at increased risk of cardiovascular disease and all-course mortality. However, whether MHO is associated with excess risk of Alzheimer’s disease (AD) in elders remains unclear. To explore the risk of AD among MHO phenotype and investigate whether MHO associates with neurodegenerative biomarkers of AD, we assessed body mass index-metabolic status phenotypes of 1199 longitudinal elders from the Alzheimer’s Disease Neuroimaging Initiative (ADNI) cohort using the Adult Treatment Panel-III (ATP- III) criteria. MHO subjects were at a significantly decreased risk for AD (adjusted HR=0.73, 95% CI: 0.54-0.97) compared with metabolically healthy normal weight (MHNW) subjects. In multivariable linear regression models, the cross-sectional associations of MHO with cerebrospinal fluid (CSF) biomarkers, brain Aβ load, and cortical structure were explored. MHO was positively correlated with CSF-Aβ (β=0.746, P=0.015), hippocampal volume (β=0.181, P=0.011), and whole brain volume (β=0.133, P=0.004). The MHO phenotype of the elder conferred a decreased risk of AD and its role may be driven by Aβ.

Combined effects of age and BMI are related to altered cortical thickness in adolescence and adulthood

Overweight and obesity are associated with functional and structural alterations in the brain, but how these associations change across critical developmental periods remains unknown. Here, we examined the relationship between age, body mass index (BMI) and cortical thickness (CT) in healthy adolescents (n = 70; 14-19 y) and adults (n = 75; 25-45 y). We also examined the relationship between adiposity, impulsivity, measured by delay discounting (DD), and CT of the inferior frontal gyrus (IFG), a region key to impulse control. A significant age-by-BMI interaction was observed in both adolescents and adults; however, the direction of this relationship differed between age groups. In adolescents, increased age-adjusted BMI Z-score attenuated age-related CT reductions globally and in frontal, temporal and occipital regions. In adults, increased BMI augmented age-related CT reductions, both globally and in bilateral parietal cortex. Although DD was unrelated to adiposity in both groups, increased DD and adiposity were both associated with reduced IFG thickness in adolescents and adults. Our findings suggest that the known age effects on CT in adolescence and adulthood are moderated by adiposity. The association between weight, cortical development and its functional implications would suggest that future studies of adolescent and adult brain development take adiposity into account.

Association between Peripheral Leptin and Adiponectin Levels and Cognitive Decline in Patients with Neurocognitive Disorders ≥65 Years

BACKGROUND

There is evidence that adipokines have roles in brain functioning and cognitive decline.

OBJECTIVE

Assess the role of leptin and adiponectin levels in predicting changes in neuro-cognitive disorders (NCD).

METHODS

The study included 205 patients over 65 years of age presenting for a one-day hospitalization for current assessment of cognitive function. Peripheral blood leptin and adiponectin levels were measured at admission. Demographic variables, body mass index (BMI), and history of hypertension were also recorded. Cognitive function was assessed by the Mini-Mental State Examination (MMSE) at admission and at later scheduled visits over a median follow-up period of 14.5 months. Conventional univariate comparisons were made between diagnosis groups (Alzheimer's disease (AD), mild NCD, vascular/mixed dementia). Changes in MMSE scores over time were examined with regard to the above variables using a linear mixed model.

RESULTS

The mean BMI was significantly lower (by 2 kg/m2, p = 0.01) in patients with AD than in patients with either mild-NCD or vascular/mixed dementia. Leptin levels were significantly higher (p = 0.043) and adiponectin levels significantly lower (p = 0.045) in patients with mild-NCD than in patients with major-NCD (AD or vascular/mixed dementia). However, the mixed model suggested no influence of the baseline levels of these two biomarkers on the course of cognitive decline.

CONCLUSION

The present study confirms the associations between leptin and adiponectin and AD or AD-related disorders but did not confirm that these peptides may be used as predictive biomarkers of cognitive decline.

Essential oil of Schisandra chinensis ameliorates cognitive decline in mice by alleviating inflammation

In this study, we aim to assess possible impacts of essential oil (SEO) from Schisandra chinensis (Turcz.) Baill. (S. chinensis) on mice with cognition impairment. Our data showed that SEO improved the cognitive ability of mice with Aβ_1-42 or lipopolysaccharides (LPS)-induced Alzheimer's disease (AD) and suppressed the production of tumor necrosis factor-a (TNF-a), interleukin-6 (IL-6), and interleukin-1β (IL-1β) in the hippocampus. Furthermore, SEO inhibited p38 activation, but had little effect on other signaling proteins in the MAPK family, such as extracellular signal-regulated kinase 1/2 (ERK1/2) and c-Jun N-terminal kinase 1/2 (JNK). The SEO and BV-2 microglia co-culture was performed to further confirm the anti-inflammatory activity of SEO. The data showed that SEO decreased nitric oxide (NO) levels in LPS-stimulated BV-2 microglia and significantly blocked LPS-induced MAPKs activation. Taken together, these findings suggested that SEO produces anti-AD effects on AD mice partly by modulating neuroinflammation through the NF-κB/MAPK signaling pathway.

Lipid-Associated Macrophages Control Metabolic Homeostasis in a Trem2-Dependent Manner

Immune cells residing in white adipose tissue have been highlighted as important factors contributing to the pathogenesis of metabolic diseases, but the molecular regulators that drive adipose tissue immune cell remodeling during obesity remain largely unknown. Using index and transcriptional single-cell sorting, we comprehensively map all adipose tissue immune populations in both mice and humans during obesity. We describe a novel and conserved Trem2+ lipid-associated macrophage (LAM) subset and identify markers, spatial localization, origin, and functional pathways associated with these cells. Genetic ablation of Trem2 in mice globally inhibits the downstream molecular LAM program, leading to adipocyte hypertrophy as well as systemic hypercholesterolemia, body fat accumulation, and glucose intolerance. These findings identify Trem2 signaling as a major pathway by which macrophages respond to loss of tissue-level lipid homeostasis, highlighting Trem2 as a key sensor of metabolic pathologies across multiple tissues and a potential therapeutic target in metabolic diseases.

Prospective of managing impaired brain insulin signalling in late onset Alzheimers disease with excisting diabetic drugs

Late onset Alzheimer's disease (AD) is the most common cause of dementia among elderly. The exact cause of the disease is until now unknown and there is no complete cure for the disease. Growing evidence suggest that AD is a metabolic disorder associated with impairment in brain insulin signalling. These findings enriched the scope for the repurposing of diabetic drugs in AD management. Even though many of these drugs are moving in a positive direction in the ongoing clinical studies, the extent of the success has seen to influence by several properties of these drugs since they were originally designed to manage the peripheral insulin resistance. In depth understandings of these properties is hence highly significant to optimise the use of diabetic drugs in the clinical management of AD; which is the primary aim of the present review article.

Risk of Incident Dementia According to Metabolic Health and Obesity Status in Late Life: A Population-Based Cohort Study

CONTEXT

The risk for dementia among subjects who are obese with normal metabolic profiles, or called metabolically healthy obese (MHO), remains uninvestigated.

OBJECTIVE

To determine the association between late-life metabolic health and obesity status and risk of incident dementia.

DESIGN

Retrospective cohort study.

SETTING

The National Health Insurance System, Republic of Korea.

PATIENTS

A total of 12,296,863 adults >50 years old who underwent health examinations from 2009 to 2012 without baseline history of dementia.

MAIN OUTCOME MEASURE

Incident overall dementia, Alzheimer's disease (AD), and vascular dementia (VaD).

RESULTS

Among subjects ≥60 years old, 363,932 (6.4%) developed dementia during a median follow-up of 65 months (interquartile range 51 to 74 months). The MHO group showed the lowest incidence of overall dementia [hazard ratio (HR) 0.85; 95% CI, 0.84 to 0.86] and AD (HR 0.87; 95% CI, 0.86 to 0.88), but not VaD, compared with the metabolically healthy nonobese group. All components of metabolic syndrome except obesity significantly elevated the risk of dementia, and these associations were more pronounced in VaD. In particular, being underweight dramatically increased the risk of dementia.

CONCLUSIONS

The MHO phenotype in late life demonstrated lower risk of overall dementia and AD but not VaD. Additional studies in other populations are warranted to elucidate current results and may predict individuals most at risk for developing dementia.

Polysaccharide of Schisandra Chinensis Fructus ameliorates cognitive decline in a mouse model of Alzheimer's disease

ETHNOPHARMACOLOGICAL RELEVANCE

Polysaccharides is an important ingredient of Schisandra Chinensis Fructus which often appears in ancient prescriptions for forgetfulness or dementia.

AIM OF THE STUDY

The purpose of our study is to investigate the effects of polysaccharides of Schisandra Chinensis Fructus (SCP) on animal model of Alzheimer's disease (AD), which is a common disease of dementia, to elucidate the traditional medical theories with modern pharmacological methods and provide a reference for further clarifying its active mechanisms.

MATERIALS AND METHODS

Hydrolysates of SCP were analyzed by HPLC. Y-maze, Morris water maze (MWM) were used for evaluating cognition processes of mice. Immunohistochemistry (IHC) was used to detect the deposition of Aβ. The levels of cytokine expression including Tumor Necrosis Factor α (TNF-α), interleukin-1β (IL-1β) and interleukin-6 (IL-6) in the hippocampus were detected by ELISA kits. Activation of astrocytes and microglia was assessed by immunofluorescence labeling GFAP and Iba-1. The phosphorylated state of various mitogen-activated protein kinase (MAPKs) signaling molecules (p38 MAPK, ERK 1/2, and JNK) and activation of nuclear factor κB (NF-κB) was studied by western blot. Histopathological changes were observed by H.E. straining.

RESULTS

SCP could significantly improve the cognition and histopathological changes of AD mice, reduce the deposition of Aβ, downregulate the expression of pro-inflammatory cytokines and the activation of glial cells in the hippocampus. Further, SCP decreased nuclear displacement of NF-κB and MAPKs phosphorylation.

CONCLUSIONS

SCP could improve the cognition of mice, and it may play an anti-AD role by activating the NF-κB/MAPK pathway to alleviate neuroinflammation.

The cause-effect relationship between bone loss and Alzheimer's disease using statistical modeling

BACKGROUND

Animal studies provide strong evidence that the CNS directly regulates bone remodeling through the actions of the hypothalamus via two distinct pathways, the neural (mediated by leptin) arm and neurohumoral (mediated by neurohormones and growth factors) arm. The impact of AD on central regulatory mechanisms of bone mass is not known.

OBJECTIVES

To test a model that assesses the relationship between hypothalamic atrophy and bone loss in Alzheimer's disease (AD) and potential mediation through neural (leptin) and neurohumoral (insulin-like growth factor -1, IGF-1) mechanisms.

HYPOTHESES

AD-related hypothalamic structural change alters neural and neurohumoral regulatory systems of bone remodeling and contributes to bone loss in early AD.

DESIGN

A secondary data analysis of data obtained in a two-year longitudinal study with path analysis and longitudinal mediation modeling.

PARTICIPANTS

The data were collected as a part of the University of Kansas Brain Aging Project, a two-year observational study of 71 older adults with early stage AD and 69 non-demented controls.

MEASUREMENTS

Demographic characteristics and measures of bone density, body composition, and hypothalamic volume, serum levels of leptin, growth hormone, and IGF-1 were collected.

RESULTS

Hypothalamic atrophy and bone loss were observed in AD group and were associated. Data modeling suggests that bone loss may precede measurable changes in the brain. Leptin increased over two years in AD and the increase in leptin was associated with hypothalamic atrophy. However, changes in leptin or IGF-1 levels did not mediate the relationship between hypothalamic atrophy and bone loss.

CONCLUSIONS

This study extends previous findings by suggesting that bone loss in AD may be related to neurodegenerative changes (atrophy) in the hypothalamus. Further studies are needed to explore the role of brain atrophy and mediating mechanisms in bone loss. Further exploring temporal relationship between bone loss and AD may have an important diagnostic value.

Leptin: role over central nervous system in epilepsy

Adipose tissue is a dynamic organ with different effects on the body. Many of these effects are mediated by leptin, a hormone strongly involved in regulation of feeding and energy metabolism. It has an important role as a mediator of neuronal excitatory activity and higher brain functions. The aim of this study was to review the association between leptin and cerebral neuronal function, in particular its anticonvulsant or convulsant effects and the possible therapeutic role for treating epilepsy. For this purpose, the databases Pubmed, Science Direct, Elsevier, ResearchGate and Scielo were searched to identify experimental studies, reviews and systematic review articles, published in English, Spanish or Portuguese. Experimental studies and the presence of leptin receptors in nervous system sites other than the hypothalamus suggest an influence on higher brain functions. Indeed several animal studies have demonstrated a role of these channels in epileptiform activity as both anticonvulsive and convulsive effects have been found. The reason for these discrepancies is unclear but provides clear evidence of a potential role of leptin and leptin therapy in epileptiform activity. The association between leptin and brain function demonstrates the importance of peripheral metabolic hormones on central nervous system and opens a new way for the development of novel therapeutic interventions in diseases like epilepsy. Nevertheless further investigations are important to clarify the dynamics and diverse actions of leptin on excitatory regulation in the brain.

The Relation of Circulating Levels of Leptin with Cognition in Patients with Alzheimer's Disease

INTRODUCTION

To investigate the relation of circulating levels of leptin with cognition in Alzheimer's disease (AD) patients.

METHODS

Thirty patients meeting the clinical diagnostic criteria for AD, and twenty-five healthy controls were enrolled into the study. At baseline, all patients underwent standing height, weight measurements, and waist circumference (in centimeters) using a standard scale. Body mass index (BMI) was then calculated as weight (in kilograms). A single 5-ml fasting blood sample was obtained from each patient. All subjects were evaluated by Turkish version of Mini Mental State Examination (MMSE), Clinical Dementia Rating (CDR) and Global Deterioration Scale (GDS).

RESULTS

The mean age of patients and controls were 72.33±10.11 and 67.20±8.95, respectively. There was not any significant difference between age of the patients and the controls (p=0.054). Both patient and control groups consisted of mostly women (60% and 56% respectively). The mean waist circumferences (WC) of patients and controls were 95.46±10.87 and 97.76±10.07, respectively and was not statistically different (p=0.424). The mean serum leptin levels in patients and controls were 5.49±4.06 ng/dL 5.71±4.45 ng/dL, respectively. Leptin levels were not statistically different between patients and controls (p=0.84). The mean MMSE scores of AD patients and controls were 17±6.54 and 27.32±2.15 respectively, and AD patients had significantly lower MMSE scores than the controls (p=0.000). The mean BMI of patients and controls were 25.72±3.98 and 27.92±3.08 respectively. The BMI of controls were higher than patients and there was statistically significant difference between two groups (p=0.029). In the patient group, there were no correlations between leptin levels and age (p=0.067), BMI (p=0.098), WC (p=0.113), MMSE (p=0.203), CDR (p=0.519) and GDS (p=0.587). Similarly in control group leptin levels were not correlated with BMI (p=0.718), WC (p=0.755) and MMSE (p=0.859).

CONCLUSION

In the present study, we could not find any relation between blood leptin levels and cognition in AD patients.

A Natural Dietary Supplement with a Combination of Nutrients Prevents Neurodegeneration Induced by a High Fat Diet in Mice

Obesity and metabolic disorders can be risk factors for the onset and development of neurodegenerative diseases. The aim of the present study was to investigate the protective effects of a natural dietary supplement (NDS), containing Curcuma longa, silymarin, guggul, chlorogenic acid and inulin, on dysmetabolism and neurodegeneration in the brains of high fat diet (HFD)-fed mice. Decrease in the expression of FACL-4, CerS-1, CerS-4, cholesterol concentration and increase in the insulin receptor expression and insulin signaling activation, were found in brains of NDS-treated HFD brains in comparison with HFD untreated-mice, suggesting that NDS is able to prevent brain lipid accumulation and central insulin resistance. In the brains of NDS-treated HFD mice, the levels of RNS, ROS and lipid peroxidation, the expression of p-ERK, H-Oxy, i-NOS, HSP60, NF-kB, GFAP, IL-1β, IL-6 and CD4 positive cell infiltration were lower than in untreated HFD mice, suggesting antioxidant and anti-inflammatory effects of NDS. The decreased expression of p-ERK and GFAP in NDS-treated HFD mice was confirmed by immunofluorescence. Lastly, a lower number of apoptotic nuclei was found in cortical sections of NDS-treated HFD mice. The present data indicate that NDS exerts neuroprotective effects in HFD mice by reducing brain fat accumulation, oxidative stress and inflammation and improving brain insulin resistance.

Mechanisms of DHA-enriched phospholipids in improving cognitive deficits in aged SAMP8 mice with high-fat diet

Recent studies have shown that a high-fat diet (HFD) is involved in both metabolic dysfunction and cognitive deficiency and that docosahexaenoic-acid-enriched phospholipids (DHA-PLs) have beneficial effects on obesity and cognitive impairment. However, there are only a few studies comparing differences between DHA-PC and DHA-PS in HFD-induced Alzheimer's disease (AD) models. After 8 weeks feeding with HFD, 10-month-old SAMP8 mice were fed with 1% (w/w) DHA-PC or 1% DHA-PS (biosynthesized from DHA-PC) for 8 weeks; we then tested the behavioral performances in the Barnes maze test and Morris maze test. The changes of the generation and accumulation of Aβ, oxidative stress, apoptosis, neuroinflammation and neurotrophic factors were also measured. The results indicated that both DHA-PC and DHA-PS significantly improved the metabolic disorders and cognitive deficits. Both DHA-PC and DHA-PS could ameliorate oxidative stress, and DHA-PS presented more notable benefits than DHA-PC on Aβ pathology, mitochondrial damage, neuroinflammation and neurotrophic factors; DHA-PS was for the first time found to increase the production of insoluble Aβ (less pathogenic) in this AD model. These data suggest that DHA-PLs can significantly improve cognitive deficiency, and the molecular mechanisms for this closely relate to the phospholipid polar groups.

Low Plasma Leptin and High Soluble Leptin Receptor Levels Are Associated With Mild Cognitive Impairment in Type 2 Diabetic Patients

Background: Metabolic disturbances, such as hyperglycemia, hyperlipidemia, and obesity, are thought to be risk factors for Alzheimer's disease.

Objective: This study aimed to investigate whether adipokine leptin and soluble leptin receptor (sOBR) levels are correlated with mild cognitive impairment (MCI) and metabolic status of the patients of type 2 diabetes mellitus (T2DM).

Methods: Total of 169 T2DM patients were recruited and divided according to the Montreal Cognitive Assessment (MoCA) score. Their cognition and metabolic parameters were extensively assessed. Plasma leptin and sOBR levels were determined by RIA and ELISA, respectively. Free leptin index (FLI) was calculated.

Results: Of 124 enrolled T2DM patients, 61 were diagnosed with MCI (MoCA < 26). In MCI group and female subgroup, leptin levels and FLI were significantly lower and sOBR concentrations were higher when compared with their respective health cognition controls (all p < 0.05). Leptin levels and FLI were positively associated with the most cognitive domains and their Waist-to-Hip Ratio (WHR), a traditional index of central obesity. Leptin, sOBR, and WHR were independent variables of MCI in all individuals (all p < 0.05). For the females, MoCA was also positively correlated with leptin (β = 0.893, p < 0.001) and negatively correlated with WHR (β = −0.363, p = 0.014). Leptin was positively correlated only with WHR (β = 0.441, p = 0.025).

Conclusions: This study showed that a high level of leptin and low level of sOBR are associated with the improved cognitive function in T2DM patients and more significantly in female individuals, while WHR, as an indicator of the visceral obesity, contributes to cognitive deficits.

Trial registration: Advanced Glycation End Products Induced Cognitive Impairment in Diabetes: BDNF Signal Meditated Hippocampal Neurogenesis ChiCTR-OCC-15006060; http://www.chictr.org.cn/showproj.aspx?proj=10536.

Intracerebroventricular Streptozotocin Induces Obesity and Dementia in Lewis Rats

BACKGROUND

Animal models of dementia associated with metabolic abnormalities play an important role in understanding the bidirectional relationships between these pathologies. Rodent strains develop cognitive dysfunctions without alteration of peripheral metabolism following intracerebroventricular administration of streptozotocin (icv-STZ).

OBJECTIVE

We aimed to estimate the effect of icv-STZ on cognitive functions and peripheral metabolism in Lewis rats, which are rarely used for the induction of cognitive abnormalities.

METHODS

Inbred adult Lewis rats were treated with single icv-STZ (3 mg/kg). Cognitive functions were assessed using Morris water maze (MWM) test and locomotion by the Open Field test. Metabolic alterations were studied using histological and biochemical analysis of brain and peripheral tissues.

RESULTS

The icv-STZ induced rapid weight decline during the first two weeks. Thereafter, the rats showed an accelerated weight gain. Three months after the icv-STZ treatment, the rats were severely obese and revealed fatty liver, pancreatic islet hypertrophy, significantly elevated levels of blood insulin, leptin, and adiponectin, but intact peripheral glucose homeostasis. The icv-STZ rats expressed amyloid-β deposits in blood vessels of leptomeningeal area, microgliosis, astrogliosis, and spongiosis in fimbria-fornix area of hippocampus. Locomotor activities of icv-STZ treated and sham-operated rats were similar. In the MWM test, the icv-STZ treated rats demonstrated severely impaired spatial learning during both acquisition and reversal phases.

CONCLUSIONS

Icv-STZ treated Lewis rats develop severe dementia associated with obesity and peripheral metabolic abnormalities. This animal model may be useful for exploring the pathophysiological relationship between obesity and dementia and provides a new tool for development of effective therapy.

Increasing Body Mass Index at Midlife is Associated with Increased Cortical Thinning in Alzheimer's Disease-Vulnerable Regions

Higher body mass index (BMI) at midlife is associated with greater decreases in cognitive function at older age as well as increased Alzheimer's disease (AD) risk, compared to those with normal BMI. Here, we tested whether BMI at midlife was associated with cortical thinning in brain regions known to be affected in early AD. We examined a large sample (n = 404) of midlife individuals (44-49 years) from the PATH population-based study. Individuals were scanned with magnetic resonance imaging (1.5T) on up to three occasions over eight years. Change in cortical thickness was modeled as a linear function of BMI and change in BMI longitudinally. Being obese was associated with thinner right frontal cortex at baseline (44-49 years). Across all individuals, increasing BMI over the 8-year study period was associated with increased cortical thinning in posterior cingulate bilaterally, as well as right lingual gyrus, anterior cingulate, and the peri-calcarine sulcus. Accelerated age-related cortical atrophy at midlife, particularly in posterior cingulate, is consistent with increased risk of AD in individuals with high BMI at this age. The findings suggest that management of body weight at midlife could reduce the risk of AD.

Animal Toxins as Therapeutic Tools to Treat Neurodegenerative Diseases

Neurodegenerative diseases affect millions of individuals worldwide. So far, no disease-modifying drug is available to treat patients, making the search for effective drugs an urgent need. Neurodegeneration is triggered by the activation of several cellular processes, including oxidative stress, mitochondrial impairment, neuroinflammation, aging, aggregate formation, glutamatergic excitotoxicity, and apoptosis. Therefore, many research groups aim to identify drugs that may inhibit one or more of these events leading to neuronal cell death. Venoms are fruitful natural sources of new molecules, which have been relentlessly enhanced by evolution through natural selection. Several studies indicate that venom components can exhibit selectivity and affinity for a wide variety of targets in mammalian systems. For instance, an expressive number of natural peptides identified in venoms from animals, such as snakes, scorpions, bees, and spiders, were shown to lessen inflammation, regulate glutamate release, modify neurotransmitter levels, block ion channel activation, decrease the number of protein aggregates, and increase the levels of neuroprotective factors. Thus, these venom components hold potential as therapeutic tools to slow or even halt neurodegeneration. However, there are many technological issues to overcome, as venom peptides are hard to obtain and characterize and the amount obtained from natural sources is insufficient to perform all the necessary experiments and tests. Fortunately, technological improvements regarding heterologous protein expression, as well as peptide chemical synthesis will help to provide enough quantities and allow chemical and pharmacological enhancements of these natural occurring compounds. Thus, the main focus of this review is to highlight the most promising studies evaluating animal toxins as therapeutic tools to treat a wide variety of neurodegenerative conditions, including Alzheimer’s disease, Parkinson’s disease, brain ischemia, glaucoma, amyotrophic lateral sclerosis, and multiple sclerosis.

An overview of complications affecting the Central Nervous System following bariatric surgery

Bariatric surgery has been considered as an effective treatment for morbid obesity. Apart from procedures related complications, a broad spectrum of neurological disorders affecting any part of neuraxis has been reported following BS. Central nervous system complications, although less common than peripheral nervous system complications, carry significant morbidity and potential mortality. Encephalopathy, behavioral and psychiatric disorders, myelopathy and optic neuropathy are the most frequently reported CNS complications. Early detection and prompt management may improve or completely reverse these neurological complications. It is essential that the treating physicians must be aware of their clinical manifestations and management, so early diagnosis and treatment can prevent patients from suffering significant neurological deficits and even death. This review discusses the clinical manifestations of these complications in detail which will help concerned physician in earlier recognition and hence prevent the delay in specific treatment.

Obesity and neurological disorders: Dietary perspective of a global menace

Obesity is considered a major public health concern throughout the world among children, adolescents, as well as adults and several therapeutic, preventive and dietary interventions are available. In addition to life style changes and medical interventions, significant milestones have been achieved in the past decades in the development of several functional foods and dietary regimens to reduce this menace. Being a multifactorial phenomenon and related to increased fat mass that adversely affects health, obesity has been associated with the development of several other co-morbidities. A great body of research and strong scientific evidence identifies obesity as an important risk factor for onset and progression of several neurological disorders. Obesity induced dyslipidaemia, metabolic dysfunction, and inflammation are attributable to the development of a variety of effects on central nervous system (CNS). Evidence suggests that neurological diseases such as Parkinson's disease and Alzheimer's disease could be initiated by various metabolic changes, related to CNS damage, caused by obesity. These metabolic changes could alter the synaptic plasticity of the neurons and lead to neural death, affecting the normal physiology of CNS. Dietary intervention in combination with exercise can affect the molecular events involved in energy metabolism and synaptic plasticity and are considered effective non-invasive strategy to counteract cognitive and neurological disorders. The present review gives an overview of the obesity and related neurological disorders and the possible dietary interventions.

Neurocalcin-delta: a potential memory-related factor in hippocampus of obese rats induced by high-fat diet

Introduction

Aberrant protein expression within the hippocampus has recently been implicated in the pathogenesis of obesity-induced memory impairment.

Objectives

The objective of the current study was to search for specific memory-related factors in the hippocampus in obese rats.

Methods

Sprague-Dawley (SD) rats were fed either a high-fat (HF) diet or normal-fat (NF) diet for 10 weeks to obtain the control (CON), diet-induced obese rats (DIO) and diet-resistant (DR) rats. D-galactose was injected subcutaneously for 10 weeks to establish model (MOD) rats with learning and memory impairment. After the hippocampus of the rats sampling, the proteome analysis was conducted using two-dimensional get electrophoresis (2-DE) combined with peptide mass fingerprinting (PMF).

Results

We found 15 differential proteins that expressed in the hippocampus in rats induced by HF diet from the 2-DE map. In addition, Neurocalcin-delta (NCALD) was nearly down-regulated in the DR rats compared with CON rats and MOD rats, which was further confirmed by Western blot, real-time PCR and ELISA results.

Conclusion

Our data demonstrates that the differential memory-related proteins were a reflection of the HF diet, but not potential factors in obesity proneness or obesity resistance. Furthermore, NCALD is proved to be a potential hippocampus-memory related factor related to obesity.

The impact of obesity on neurodegenerative diseases

Neurodegenerative diseases are a growing health concern. The increasing incidences of these disorders have a great impact on the patients' quality of life. Although the mechanisms of neurodegenerative diseases are still far from being clarified, several studies look for new discoveries about their pathophysiology and prevention. Furthermore, evidence has shown a strong correlation between obesity and the development of Alzheimer's disease (AD) and Parkinson's disease (PD). Metabolic changes caused by overweight are related to damage to the central nervous system (CNS), which can lead to neural death, either by apoptosis or cell necrosis, as well as alter the synaptic plasticity of the neuron. This review aims to show the association between neurodegenerative diseases, focusing on AD and PD, and metabolic alterations.

Geniposide attenuates the level of Aβ1-42 via enhancing leptin signaling in cellular and APP/PS1 transgenic mice

An large body of evidence indicates that leptin has protective role against Alzheimer's disease, where it reduces β-amyloid (Aβ) production in both cell culture and animal models. Our previous studies revealed that geniposide could attenuate the production of Aβ_1-42 and antagonize the neurotoxicity of Aβ_1-42 in neurons. However, the mechanism that underlies these effects remains to be clarified. To investigate whether leptin signaling is involved in regulating the production of Aβ_1-42 by geniposide, we treated primary neurons with leptin antagonist (LA), and determined the influence of LA on the activities of leptin signaling molecules and the expressions of secretases associated with the production of Aβ_1-42. The finding showed that, accompanied with the inhibition on the level of Aβ_1-42 in primary neurons and APP/PS1 transgenic mice, geniposide induced the phosphorylation of JAK2 and STAT3, regulated the expression level of α- and β-secretase, and all of these could be prevented by the pre-incubation with LA. The results of this study suggest that geniposide may regulate the production of Aβ_1-42 via leptin signaling.

Relationship of galectin-3 with obesity, IL-6, and CRP in women

PURPOSE

To evaluate the association of galectin-3 (Gal3) with obesity and inflammatory status in a cohort of metabolically healthy, predominantly African-American women with varying cardiovascular disease (CVD) risk as determined by CRP levels.

METHODS

We assessed the association between BMI and serum levels of Gal3, IL-6, CRP, and adiponectin in metabolically healthy women (N = 97) to determine the overall association between Gal3, obesity, and inflammation in groups at different CVD risk.

RESULTS

Obese women had significantly higher serum Gal3 compared to non-obese participants (P = 0.0016), although Gal3 levels were comparable among different classes of obesity. BMI (R ² = 0.1406, P = 0.0013), IL-6 (R ² = 0.0689, P = 0.035), and CRP (R ² = 0.0468, P = 0.0419), but not adiponectin, positively predicted the variance of Gal3 levels in the total study population. However, the predicting effect of BMI (R ² = 0.2923, P = 0.0125) and inflammation (R ² = 0.3138, P = 0.038) on Gal3 was only present in women at low/moderate risk of CVD (CRP ≤ 3 µg/mL).

CONCLUSIONS

Gal3 is positively correlated with obesity and inflammation in women, while the presence of elevated CVD risk may disturb the strength of Gal3 as a biomarker of inflammation.

Relationship between adipokines and lipid profile in postmenopausal women with different apolipoprotein E genotypes

The aim of the authors of this study was to clarify the relationships among apolipoprotein E (ApoE) genotype, blood pressure, lipid profile, serum leptin, and adiponectin in healthy postmenopausal women. The study was conducted between March 2011 and December 2012 on 266 participants aged 50-65 years from the Institute of Rural Health in Lublin, Poland. Results showed that women had four combinations of genotypes: ɛ2/ɛ3, ɛ3/ɛ3, ɛ3/ɛ4, and ɛ4/ɛ4. Carriers of different genotypes did not differ in terms of age, body mass index (BMI), blood pressure, total cholesterol, high-density lipoprotein (HDL) cholesterol, and adiponectin levels. Mean low-density lipoprotein (LDL) cholesterol levels were higher in ε4 carriers compared to non-carriers. Fasting serum leptin concentrations were higher in homozygotes ɛ4/ɛ4. Leptin correlated positively with BMI in all study groups and with LDL in ɛ2/ɛ3, ɛ3/ɛ3, and ɛ3/ɛ4. Adiponectin correlated negatively with triglycerides in ɛ2/ɛ3, ɛ3/ɛ3, and ɛ3/ɛ4 and positively with HDL in ɛ2/ɛ3 carriers. Adipokines were not associated with blood pressure. Multiple regression analyses demonstrated associations among leptin, ApoE ɛ4/ɛ4, BMI, and LDL, and among adiponectin, BMI, and triglycerides. In healthy postmenopausal women ɛ4/ɛ4 genotype was associated with lower leptin levels. Homozygosity ɛ4/ɛ4 was associated with a more atherogenic lipid profile and possibly dysregulation of leptin and adiponectin signaling in lipid metabolism.

Insulin resistance, dyslipidemia, and apolipoprotein E interactions as mechanisms in cognitive impairment and Alzheimer's disease

An increased risk for Alzheimer's disease is associated with dyslipidemia and insulin resistance. A separate literature shows the genetic risk for developing Alzheimer's disease is strongly correlated to the presence of the E4 isoform of the apolipoprotein E carrier protein. Understanding how apolipoprotein E carrier protein, lipids, amyloid β peptides, glucose, central nervous system insulin, and peripheral insulin interact with one another in Alzheimer's disease is an area of increasing interest. Here, we will review the evidence relating apolipoprotein E carrier protein, lipids, and insulin action to Alzheimer's disease and Aβ peptides and then propose mechanisms as to how these factors might interact with one another to impair cognition and promote Alzheimer's disease.

Low Leptin Availability as a Risk Factor for Dementia in Chilean Older People

OBJECTIVE

The aim was to study the role of leptin in the development of dementia.

METHODS

Follow-up of the ALEXANDROS cohorts, with baseline measurements in 2000. From 1,136 available subjects free of dementia at baseline, 667 subjects had frozen baseline blood samples for measuring leptin and soluble leptin receptor (sOB-R). The free leptin index (FLI) was calculated as the ratio of leptin to sOB-R. Dementia was defined as an MMSE score <22 and a score >5 in the Pfeffer Activities Questionnaire.

RESULTS

After 15 years of follow-up, 42 incident cases of dementia were identified. No difference in serum leptin was observed between people with and without dementia, but sOB-R was higher in demented than in nondemented subjects (sOB-R: 44.94 ± 23.97 vs. 33.73 ± 21.13 ng/ml). The adjusted risk for dementia increased, the higher the log sOB (hazard ratio = 3.58; 95% CI 1.72-7.45, p = 0.001).

CONCLUSION

Lower availability of free leptin was found in demented than in nondemented people, suggesting a role of leptin in cognition.

Secret talk between adipose tissue and central nervous system via secreted factors-an emerging frontier in the neurodegenerative research

First seen as a storage organ, the white adipose tissue (WAT) is now considered as an endocrine organ. WAT can produce an array of bioactive factors known as adipokines acting at physiological level and playing a vital role in energy metabolism as well as in immune response. The global effect of adipokines in metabolic activities is well established, but their impact on the physiology and the pathophysiology of the central nervous system (CNS) remains poorly defined. Adipokines are not only produced by the WAT but can also be expressed in the CNS where receptors for these factors are present. When produced in periphery and to affect the CNS, these factors may either cross the blood brain barrier (BBB) or modify the BBB physiology by acting on cells forming the BBB. Adipokines could regulate neuroinflammation and oxidative stress which are two major physiological processes involved in neurodegeneration and are associated with many chronic neurodegenerative diseases. In this review, we focus on four important adipokines (leptin, resistin, adiponectin, and TNFα) and one lipokine (lysophosphatidic acid-LPA) associated with autotaxin, its producing enzyme. Their potential effects on neurodegeneration and brain repair (neurogenesis) will be discussed. Understanding and regulating these adipokines could be an interesting lead to novel therapeutic strategy in order to counteract neurodegenerative disorders and/or promote brain repair.

Obesity, diabetes, and leptin resistance promote tau pathology in a mouse model of disease

Obesity and type 2 diabetes mellitus (T2DM) convey an increased risk for developing dementia. The microtubule-associated protein tau is implicated in neurodegenerative disease by undergoing hyperphosphorylation and aggregation, leading to cytotoxicity and neurodegeneration. Enzymes involved in the regulation of tau phosphorylation, such as GSK3β, are tightly associated with pathways found to be dysregulated in T2DM. We have shown previously that leptin-resistant mice, which develop obesity and a diabetic phenotype, display elevated levels of tau phosphorylation. Here we show cells cultured with leptin, an adipokine shown to have neuroprotective effects, reduces tau phosphorylation. To explore how this mechanism works in vivo we transduced an existing diabetic mouse line (Lepr(db/db)) with a tau mutant (tau(P301L)) via adeno-associated virus (AAV). The resulting phenotype included a striking increase in tau phosphorylation and the number of neurofibrillary tangles (NFTs) found within the hippocampus. We conclude that leptin resistance-induced obesity and diabetes accelerates the development of tau pathology. This model of metabolic dysfunction and tauopathy provides a new system in which to explore the mechanisms underlying the ways in which leptin resistance and diabetes influence development of tau pathology, and may ultimately be related to the development of NFTs.

Efficient Test and Visualization of Multi-Set Intersections

Identification of sets of objects with shared features is a common operation in all disciplines. Analysis of intersections among multiple sets is fundamental for in-depth understanding of their complex relationships. However, so far no method has been developed to assess statistical significance of intersections among three or more sets. Moreover, the state-of-the-art approaches for visualization of multi-set intersections are not scalable. Here, we first developed a theoretical framework for computing the statistical distributions of multi-set intersections based upon combinatorial theory, and then accordingly designed a procedure to efficiently calculate the exact probabilities of multi-set intersections. We further developed multiple efficient and scalable techniques to visualize multi-set intersections and the corresponding intersection statistics. We implemented both the theoretical framework and the visualization techniques in a unified R software package, SuperExactTest. We demonstrated the utility of SuperExactTest through an intensive simulation study and a comprehensive analysis of seven independently curated cancer gene sets as well as six disease or trait associated gene sets identified by genome-wide association studies. We expect SuperExactTest developed by this study will have a broad range of applications in scientific data analysis in many disciplines.

Leptin in Alzheimer's disease

Alzheimer's disease (AD) is the most common cause of progressive dementia in the elderly population. AD is histologically characterized by accumulation of amyloid-β protein (Aβ) on extracellular plaques and deposition of hyperphosphorylated tau protein in intracellular neurofibrillary tangles. Several studies have shown that obesity may precede dementia and that lifestyle factors play a critical role in the onset of AD. Furthermore, accumulating evidence indicates that obesity is an independent risk factor for developing AD. In this scenario, the understanding of the role of adipose tissue in brain health is essential to clarify the establishment of demential processes. The objective of this work was to review studies regarding leptin, an anorexigenic peptide hormone synthesized in adipocytes, in the context of dementia. Some authors proposed that leptin evaluation might be a better predictor of dementia than traditional anthropometric measures. Leptin, once established as a biomarker, could enhance the understanding of late-onset AD risk over the life course, as well as the clinical progression of prodromal state to manifested AD. Other studies have proposed that leptin presents neuroprotective activities, which could be explained by inhibiting the amyloidogenic process, reducing the levels of tau protein phosphorylation and improving the cognitive function.