Metabolic Syndrome and Neuroprotection

The role of the brain renin-angiotensin system in Parkinson´s disease

The renin-angiotensin system (RAS) was classically considered a circulating hormonal system that regulates blood pressure. However, different tissues and organs, including the brain, have a local paracrine RAS. Mutual regulation between the dopaminergic system and RAS has been observed in several tissues. Dysregulation of these interactions leads to renal and cardiovascular diseases, as well as progression of dopaminergic neuron degeneration in a major brain center of dopamine/angiotensin interaction such as the nigrostriatal system. A decrease in the dopaminergic function induces upregulation of the angiotensin type-1 (AT1) receptor activity, leading to recovery of dopamine levels. However, AT1 receptor overactivity in dopaminergic neurons and microglial cells upregulates the cellular NADPH-oxidase-superoxide axis and Ca2+ release, which mediate several key events in oxidative stress, neuroinflammation, and α-synuclein aggregation, involved in Parkinson's disease (PD) pathogenesis. An intraneuronal antioxidative/anti-inflammatory RAS counteracts the effects of the pro-oxidative AT1 receptor overactivity. Consistent with this, an imbalance in RAS activity towards the pro-oxidative/pro-inflammatory AT1 receptor axis has been observed in the substantia nigra and striatum of several animal models of high vulnerability to dopaminergic degeneration. Interestingly, autoantibodies against angiotensin-converting enzyme 2 and AT1 receptors are increased in PD models and PD patients and contribute to blood-brain barrier (BBB) dysregulation and nigrostriatal pro-inflammatory RAS upregulation. Therapeutic strategies addressed to the modulation of brain RAS, by AT1 receptor blockers (ARBs) and/or activation of the antioxidative axis (AT2, Mas receptors), may be neuroprotective for individuals with a high risk of developing PD or in prodromal stages of PD to reduce progression of the disease.

The role of autophagy in the treatment of type II diabetes and its complications: a review

Type II diabetes mellitus (T2DM) is a chronic metabolic disease characterized by prolonged hyperglycemia and insulin resistance (IR). Its incidence is increasing annually, posing a significant threat to human life and health. Consequently, there is an urgent requirement to discover effective drugs and investigate the pathogenesis of T2DM. Autophagy plays a crucial role in maintaining normal islet structure. However, in a state of high glucose, autophagy is inhibited, resulting in impaired islet function, insulin resistance, and complications. Studies have shown that modulating autophagy through activation or inhibition can have a positive impact on the treatment of T2DM and its complications. However, it is important to note that the specific regulatory mechanisms vary depending on the target organ. This review explores the role of autophagy in the pathogenesis of T2DM, taking into account both genetic and external factors. It also provides a summary of reported chemical drugs and traditional Chinese medicine that target the autophagic pathway for the treatment of T2DM and its complications.

Neuroprotection in metabolic syndrome by environmental enrichment. A lifespan perspective

Metabolic syndrome (MetS) is defined by the concurrence of different metabolic conditions: obesity, hypertension, dyslipidemia, and hyperglycemia. Its incidence has been increasingly rising over the past decades and has become a global health problem. MetS has deleterious consequences on the central nervous system (CNS) and neurological development. MetS can last several years or be lifelong, affecting the CNS in different ways and treatments can help manage condition, though there is no known cure. The early childhood years are extremely important in neurodevelopment, which extends beyond, encompassing a lifetime. Neuroplastic changes take place all life through - childhood, adolescence, adulthood, and old age - are highly sensitive to environmental input. Environmental factors have an important role in the etiopathogenesis and treatment of MetS, so environmental enrichment (EE) stands as a promising non-invasive therapeutic approach. While the EE paradigm has been designed for animal housing, its principles can be and actually are applied in cognitive, sensory, social, and physical stimulation programs for humans. Here, we briefly review the central milestones in neurodevelopment at each life stage, along with the research studies carried out on how MetS affects neurodevelopment at each life stage and the contributions that EE models can provide to improve health over the lifespan.

High glucose inhibits neural differentiation by excessive autophagy <em>via</em> peroxisome proliferator-activated receptor gamma

The high prevalence of prediabetes and diabetes globally has led to the widespread occurrence of severe complications, such as diabetic neuropathy, which is a result of chronic hyperglycemia. Studies have demonstrated that maternal diabetes can lead to neural tube defects by suppressing neurogenesis during neuroepithelium development. While aberrant autophagy has been associated with abnormal neuronal differentiation, the mechanism by which high glucose suppresses neural differentiation in stem cells remains unclear. Therefore, we developed a neuronal cell differentiation model of retinoic acid induced P19 cells to investigate the impact of high glucose on neuronal differentiation in vitro. Our findings indicate that high glucose (HG) hinders neuronal differentiation and triggers excessive. Furthermore, HG treatment significantly reduces the expression of markers for neurons (Tuj1) and glia (GFAP), while enhancing autophagic activity mediated by peroxisome proliferator-activated receptor gamma (PPARγ). By manipulating PPARγ activity through pharmacological approaches and genetically knocking it down using shRNA, we discovered that altering PPARγ activity affects the differentiation of neural stem cells exposed to HG. Our study reveals that PPARγ acts as a downstream mediator in high glucose-suppressed neural stem cell differentiation and that refining autophagic activity via PPARγ at an appropriate level could improve neuronal differentiation efficiency. Our data provide novel insights and potential therapeutic targets for the clinical management of gestational diabetes mellitus.

Molecular and neural roles of sodium-glucose cotransporter 2 inhibitors in alleviating neurocognitive impairment in diabetic mice

Diabetes causes a variety of molecular changes in the brain, making it a real risk factor for the development of cognitive dysfunction. Complex pathogenesis and clinical heterogeneity of cognitive impairment makes the efficacy of current drugs limited. Sodium-glucose cotransporter 2 inhibitors (SGLT2i) gained our attention as drugs with potential beneficial effects on the CNS. In the present study, these drugs ameliorated the cognitive impairment associated with diabetes. Moreover, we verified whether SGLT2i can mediate the degradation of amyloid precursor protein (APP) and modulation of gene expression (Bdnf, Snca, App) involved in the control of neuronal proliferation and memory. The results of our research proved the participation of SGLT2i in the multifactorial process of neuroprotection. SGLT2i attenuate the neurocognitive impairment through the restoration of neurotrophin levels, modulation of neuroinflammatory signaling, and gene expression of Snca, Bdnf, and App in the brain of diabetic mice. The targeting of the above-mentioned genes is currently seen as one of the most promising and developed therapeutic strategies for diseases associated with cognitive dysfunction. The results of this work could form the basis of a future administration of SGLT2i in diabetics with neurocognitive impairment.

AT1 receptor autoantibodies mediate effects of metabolic syndrome on dopaminergic vulnerability

The metabolic syndrome has been associated to chronic peripheral inflammation and related with neuroinflammation and neurodegeneration, including Parkinson's disease. However, the responsible mechanisms are unclear. Previous studies have involved the brain renin-angiotensin system in progression of Parkinson's disease and the angiotensin receptor type 1 (AT1) has been recently revealed as a major marker of dopaminergic vulnerability in humans. Dysregulation of tissue renin-angiotensin system is a key common mechanism for all major components of metabolic syndrome. Circulating AT1 agonistic autoantibodies have been observed in several inflammation-related peripheral processes, and activation of AT1 receptors of endothelial cells, dopaminergic neurons and glial cells have been observed to disrupt endothelial blood -brain barrier and induce neurodegeneration, respectively. Using a rat model, we observed that metabolic syndrome induces overactivity of nigral pro-inflammatory renin-angiotensin system axis, leading to increase in oxidative stress and neuroinflammation and enhancing dopaminergic neurodegeneration, which was inhibited by treatment with AT1 receptor blockers (ARBs). In rats, metabolic syndrome induced the increase in circulating levels of LIGHT and other major pro-inflammatory cytokines, and 27-hydroxycholesterol. Furthermore, the rats showed a significant increase in serum levels of proinflammatory AT1 and angiotensin converting enzyme 2 (ACE2) autoantibodies, which correlated with levels of several metabolic syndrome parameters. We also found AT1 and ACE2 autoantibodies in the CSF of these rats. Effects of circulating autoantibodies were confirmed by chronic infusion of AT1 autoantibodies, which induced blood-brain barrier disruption, an increase in the pro-inflammatory renin-angiotensin system activity in the substantia nigra and a significant enhancement in dopaminergic neuron death in two different rat models of Parkinson's disease. Observations in the rat models, were analyzed in a cohort of parkinsonian and non-parkinsonian patients with or without metabolic syndrome. Non-parkinsonian patients with metabolic syndrome showed significantly higher levels of AT1 autoantibodies than non-parkinsonian patients without metabolic syndrome. However, there was no significant difference between parkinsonian patients with metabolic syndrome or without metabolic syndrome, which showed higher levels of AT1 autoantibodies than non-parkinsonian controls. This is consistent with our recent studies, showing significant increase of AT1 and ACE2 autoantibodies in parkinsonian patients, which was related to dopaminergic degeneration and neuroinflammation. Altogether may lead to a vicious circle enhancing the progression of the disease that may be inhibited by strategies against production of these autoantibodies or AT1 receptor blockers (ARBs).

Factors Associated with Undertaking Health-Promoting Activities by Older Women at High Risk of Metabolic Syndrome

BACKGROUND

The complexity of health problems concerning women aged ≥60 years makes it necessary to develop effective, low-cost strategies involving biopsychosocial interventions. The aim of this study is to identify the factors associated with undertaking health-promoting activities by older women at high risk of metabolic syndrome (MetS) with or without depressive symptoms.

METHODS

The study group consisted of 70 older women (62-84 years old) undertaking regular physical activity. A self-developed questionnaire (used to determine the living situation, selected lifestyle components and health problems), the Perceived Stress Questionnaire (PSQ) and the Geriatric Depression Scale (GDS) were used.

RESULTS

In the study group undertaking regular physical activity, 40% had increased symptoms of depression (D group), and 60% were classified as non-depressed (ND group). The D group had a higher general stress level (t = -6.18, p = 0.001). Improving and/or maintaining physical fitness was identified as the greatest motivation in both groups. Willingness to spend time with other people significantly differed between the two groups (χ² = 4.148, p = 0.042). The sole factor significantly differentiating between both groups was lack of time (χ² = 8.777, p = 0.003).

CONCLUSIONS

Motivations and barriers to undertaking health-promoting activities and levels of perceived stress were significantly different between the depressed and non-depressed groups. It is important to encourage primary care physicians to perform screening tests for late-life depression and to provide information on where therapeutic interventions are available for patients with symptoms of MetS and coexisting depressive symptoms.

Brain sex-dependent alterations after prolonged high fat diet exposure in mice

We examined effects of exposing female and male mice for 33 weeks to 45% or 60% high fat diet (HFD). Males fed with either diet were more vulnerable than females, displaying higher and faster increase in body weight and more elevated cholesterol and liver enzymes levels. Higher glucose metabolism was revealed by PET in the olfactory bulbs of both sexes. However, males also displayed altered anterior cortex and cerebellum metabolism, accompanied by a more prominent brain inflammation relative to females. Although both sexes displayed reduced transcripts of neuronal and synaptic genes in anterior cortex, only males had decreased protein levels of AMPA and NMDA receptors. Oppositely, to anterior cortex, cerebellum of HFD-exposed mice displayed hypometabolism and transcriptional up-regulation of neuronal and synaptic genes. These results indicate that male brain is more susceptible to metabolic changes induced by HFD and that the anterior cortex versus cerebellum display inverse susceptibility to HFD.

Association of dyslipidemia and hypoxemia in patients with obstructive sleep apnea hypopnea syndrome: a cross-sectional study

OBJECTIVE

Studies have shown that dyslipidemia may contribute to chronic tissue hypoxia. However, it remains unclear whether dyslipidemia affects chronic hypoxia in patients with obstructive sleep apnea hypopnea syndrome (OSAHS). Therefore, from a clinical practice perspective, the purpose of this study was to investigate the effect of dyslipidemia on chronic hypoxia in OSAHS patients.

METHOD

In athis cross-sectional survey, 320 consecutive OSAHS patients were enrolled. By screening under different conditions, 211 patients were finally enrolled in the study. Patients were grouped according to apnea-hypopnea index (AHI), into a mild-to-moderate (AHI < 30) group and severe OSAHS group (AHI ≥ 30).

RESULTS

Comparative analysis shows that 45% of mild-to-moderate OSAHS patients had severe hypoxemia. Univariate and multivariate regression analyses showed that AHI, triglycerides (TG), and high-density lipoprotein cholesterol (HDL-C) had independent effects on lowest oxygen saturation (LSpO₂), and that AHI and TG levels had independent effects on mean oxygen saturation (MSpO₂). The patients were stratified by AHI and further grouped by TG and HDL-C abnormalities in each subgroup. A difference analysis showed that LSpO₂ and MSpO₂ were significantly decreased in OSAHS patients with dyslipidemia (high TG and low HDL-C levels) in the AHI ≥ 30 subgroup (P < 0.05). Finally, in order to further clarify the impact of the selected indicators of hypoxemia in OSAHS patients with different degrees of airway obstruction, subgroup analysis was conducted based on OSAHS severity. In the AHI < 30 subgroup, LSpO₂ was significantly decreased in patients with abnormal HDL-C.

CONCLUSION

The results of this study indicate that abnormalities in TG and HDL-C, in addition to upper airway obstruction, are among the factors that aggravate chronic hypoxia in tissues from OSAHS patients.

Accelerated amyloid angiopathy and related vascular alterations in a mixed murine model of Alzheimer´s disease and type two diabetes

BACKGROUND

While aging is the main risk factor for Alzheimer´s disease (AD), emerging evidence suggests that metabolic alterations such as type 2 diabetes (T2D) are also major contributors. Indeed, several studies have described a close relationship between AD and T2D with clinical evidence showing that both diseases coexist. A hallmark pathological event in AD is amyloid-β (Aβ) deposition in the brain as either amyloid plaques or around leptomeningeal and cortical arterioles, thus constituting cerebral amyloid angiopathy (CAA). CAA is observed in 85-95% of autopsy cases with AD and it contributes to AD pathology by limiting perivascular drainage of Aβ.

METHODS

To further explore these alterations when AD and T2D coexist, we have used in vivo multiphoton microscopy to analyze over time the Aβ deposition in the form of plaques and CAA in a relevant model of AD (APPswe/PS1dE9) combined with T2D (db/db). We have simultaneously assessed the effects of high-fat diet-induced prediabetes in AD mice. Since both plaques and CAA are implicated in oxidative-stress mediated vascular damage in the brain, as well as in the activation of matrix metalloproteinases (MMP), we have also analyzed oxidative stress by Amplex Red oxidation, MMP activity by DQ™ Gelatin, and vascular functionality.

RESULTS

We found that prediabetes accelerates amyloid plaque and CAA deposition, suggesting that initial metabolic alterations may directly affect AD pathology. T2D significantly affects vascular pathology and CAA deposition, which is increased in AD-T2D mice, suggesting that T2D favors vascular accumulation of Aβ. Moreover, T2D synergistically contributes to increase CAA mediated oxidative stress and MMP activation, affecting red blood cell velocity.

CONCLUSIONS

Our data support the cross-talk between metabolic disease and Aβ deposition that affects vascular integrity, ultimately contributing to AD pathology and related functional changes in the brain microvasculature.

Cognitive impairment and type 2 diabetes mellitus: Focus of SGLT2 inhibitors treatment

Gliflozins are a novel class of oral anti-diabetic drugs, acting as inhibitors of sodium-glucose co-transporters (SGLTs) through the proximal convoluted tubules (PCT) and intestinal epithelium. The sodium-glucose co-transporters 2 (SGLT2) are mainly expressed in S1 and S2 segments of the proximal convoluted tubule in the kidneys. Clinical guidelines recommend their use especially in Type 2 Diabetes mellitus (T2DM) patients with vascular complications and/or heart failure highlighting the importance of sodium-glucose co-transporter 2 inhibitors (SGLT2i) pleiotropic effects. Interestingly, cognitive decline is a widely recognized complication of T2DM and, in addition, to clarify its pathophysiology, there is an urgent need to understand how and if diabetes therapies can control diabetes-related cognitive dysfunction. At the time, although SGLT2 proteins are present in the Central Nervous System (CNS), the SGLT2i effects on cognitive impairments remain partly unknown. In pre-clinical studies, SGLT2i ameliorates cognitive dysfunction in obese and T2DM mice, reducing oxidative stress, neuroinflammation and improving neuronal plasticity and mitochondrial brain pathway. In addition, SGLT2i could bring back mTOR to a physiological state of activation, stopping neurodegenerative diseases' onset or progression. Instead, clinical studies on T2DM-related cognitive dysfunction treated by SGLT2i are much more limited. For these reasons, further studies are needed to better elucidate if SGLT2i therapy can affect T2DM-related cognitive decline. In this scenario, this review aims to summarize the state of knowledge on the role of SGLT2i in T2DM-related cognitive dysfunction and stimulate new clinical trials.

Imaging with [99mTc]HMPAO - a novel perspective: investigation of [99mTc]HMPAO leg muscle uptake in metabolic diseases

BACKGROUND

Sensitive imaging modalities in the diagnosis of microcircular complications of the lower extremities induced by metabolic diseases are becoming a focus of interest.

PURPOSE

To investigate the [^99mTc]HMPAO uptake of the legs in type 2 diabetes mellitus (T2DM) and obesity, and to search for associations with clinical parameters and nerve conducting studies.

MATERIAL AND METHODS

A total of 57 patients with controlled T2DM and 46 obese participants without DM were enrolled in the study. [^99mTc]HMPAO SPECT/CT examinations were performed to evaluate the radiopharmaceutical accumulation of the legs. For the quantitative assessment of tracer uptake, standardized uptake value (SUV_peak) was measured in fixed spheric volumes of interest placed on both sural muscles on the attenuation-corrected images. Measurement of current perception threshold applying Neurometer (NM-01/CPT) was used to evaluate peripheral nerve dysfunction. Laboratory parameters assessing the glucose homeostasis of the study participants were also measured.

RESULTS

In the diabetic group, significantly lower leg SUV values were detected compared to the non-DM obese group (median: 0.517 vs. 0.607; P < 0.001). Body mass index (BMI) (P < 0.0001), age (P = 0.0283), HbA1c (P = 0.0068), and glucose level (P = 0.0044) proved to be significant predictors of muscle tracer uptake. Neurometer studies showed positive correlation with HbA1c levels in the T2DM group (P = 0.0002).

CONCLUSION

We assume that [^99mTc]HMPAO uptake of leg muscles is associated with microcirculation, so quantitative [^99mTc]HMPAO SPECT/CT might be a sensitive method for evaluating lower limb microvascular alterations. BMI, age, HbA1c, and glucose level may be significant predictors of peripheral vascular abnormalities triggered by metabolic disturbances.

Impaired glucose metabolism reduces the neuroprotective action of adipocytokines in cognitively normal older adults with insulin resistance

Evidence suggests that aging-related dysfunctions of adipose tissue and metabolic disturbances increase the risk of diabetes and metabolic syndrome (MtbS), eventually leading to cognitive impairment and dementia. However, the neuroprotective role of adipocytokines in this process has not been specifically investigated. The present study aims to identify metabolic alterations that may prevent adipocytokines from exerting their neuroprotective action in normal ageing. We hypothesize that neuroprotection may occur under insulin resistance (IR) conditions as long as there are no other metabolic alterations that indirectly impair the action of adipocytokines, such as hyperglycemia. This hypothesis was tested in 239 cognitively normal older adults (149 females) aged 52 to 87 years (67.4 ± 5.9 yr). We assessed whether the homeostasis model assessment-estimated insulin resistance (HOMA-IR) and the presence of different components of MtbS moderated the association of plasma adipocytokines (i.e., adiponectin, leptin and the adiponectin to leptin [Ad/L] ratio) with cognitive functioning and cortical thickness. The results showed that HOMA-IR, circulating triglyceride and glucose levels moderated the neuroprotective effect of adipocytokines. In particular, elevated triglyceride levels reduced the beneficial effect of Ad/L ratio on cognitive functioning in insulin-sensitive individuals; whereas under high IR conditions, it was elevated glucose levels that weakened the association of the Ad/L ratio with cognitive functioning and with cortical thickness of prefrontal regions. Taken together, these findings suggest that the neuroprotective action of adipocytokines is conditioned not only by whether cognitively normal older adults are insulin-sensitive or not, but also by the circulating levels of triglycerides and glucose, respectively.

Caffeic Acid on Metabolic Syndrome: A Review

Metabolic syndrome (MetS) is a constellation of risk factors that may lead to a more sinister disease. Raised blood pressure, dyslipidemia in the form of elevated triglycerides and lowered high-density lipoprotein cholesterol, raised fasting glucose, and central obesity are the risk factors that could lead to full-blown diabetes, heart disease, and many others. With increasing sedentary lifestyles, coupled with the current COVID-19 pandemic, the numbers of people affected with MetS will be expected to grow in the coming years. While keeping these factors checked with the polypharmacy available currently, there is no single strategy that can halt or minimize the effect of MetS to patients. This opens the door for a more natural way of controlling the disease. Caffeic acid (CA) is a phytonutrient belonging to the flavonoids that can be found in abundance in plants, fruits, and vegetables. CA possesses a wide range of beneficial properties from antioxidant, immunomodulatory, antimicrobial, neuroprotective, antianxiolytic, antiproliferative, and anti-inflammatory activities. This review discusses the current discovery of the effect of CA against MetS.

Glucose-level dependent brain hypometabolism in type 2 diabetes mellitus and obesity

BACKGROUND

Metabolic syndrome and its individual components lead to wide-ranging consequences, many of which affect the central nervous system. In this study, we compared the [18F]FDG regional brain metabolic pattern of participants with type 2 diabetes mellitus (T2DM) and non-DM obese individuals.

METHODS

In our prospective study, 51 patients with controlled T2DM (ages 50.6 ± 8.0 years) and 45 non-DM obese participants (ages 52.0 ± 9.6 years) were enrolled. Glucose levels measured before PET/CT examination (pre-PET glucose) as well as laboratory parameters assessing glucose and lipid status were determined. NeuroQ application (NeuroQTM 3.6, Syntermed, Philips) was used to evaluate regional brain metabolic differences. [18F]FDG PET/CT (AnyScan PC, Mediso) scans, estimating brain metabolism, were transformed to MNI152 brain map after T1 registration and used for SPM-based group comparison of brain metabolism corrected for pre-PET glucose, and correlation analysis with laboratory parameters.

RESULTS

NeuroQ analysis did not reveal significant regional metabolic defects in either group. Voxel-based group comparison revealed significantly (PFWE<0.05) decreased metabolism in the region of the precuneus and in the right superior frontal gyrus (rSFG) in the diabetic group as compared to the obese patients. Data analysis corrected for pre-PET glucose level showed a hypometabolic difference only in the rSFG in T2DM. Voxel-based correlation analysis showed significant negative correlation of the metabolism in the following brain regions with pre-PET glucose in diabetes: precuneus, left posterior orbital gyrus, right calcarine cortex and right orbital part of inferior frontal gyrus; whilst in the obese group only the right rolandic (pericentral) operculum proved to be sensitive to pre-PET glucose level.

CONCLUSIONS

To our knowledge, this is the first study to perform pre-PET glucose level corrected comparative analysis of brain metabolism in T2DM and obesity. We also examined the pre-PET glucose level dependency of regional cerebral metabolism in the two groups separately. Large-scale future studies are warranted to perform further correlation analysis with the aim of determining the effects of metabolic disturbances on brain metabolism.

Cardiac Autonomic Neuropathy: A Progressive Consequence of Chronic Low-Grade Inflammation in Type 2 Diabetes and Related Metabolic Disorders

Cardiac autonomic neuropathy (CAN) is one of the earliest complications of type 2 diabetes (T2D), presenting a silent cause of cardiovascular morbidity and mortality. Recent research relates the pathogenesis of cardiovascular disease in T2D to an ensuing chronic, low-grade proinflammatory and pro-oxidative environment, being the hallmark of the metabolic syndrome. Metabolic inflammation emerges as adipose tissue inflammatory changes extending systemically, on the advent of hyperglycemia, to reach central regions of the brain. In light of changes in glucose and insulin homeostasis, dysbiosis or alteration of the gut microbiome (GM) emerges, further contributing to inflammatory processes through increased gut and blood-brain barrier permeability. Interestingly, studies reveal that the determinants of oxidative stress and inflammation progression exist at the crossroad of CAN manifestations, dictating their evolution along the natural course of T2D development. Indeed, sympathetic and parasympathetic deterioration was shown to correlate with markers of adipose, vascular, and systemic inflammation. Additionally, evidence points out that dysbiosis could promote a sympatho-excitatory state through differentially affecting the secretion of hormones and neuromodulators, such as norepinephrine, serotonin, and γ-aminobutyric acid, and acting along the renin-angiotensin-aldosterone axis. Emerging neuronal inflammation and concomitant autophagic defects in brainstem nuclei were described as possible underlying mechanisms of CAN in experimental models of metabolic syndrome and T2D. Drugs with anti-inflammatory characteristics provide potential avenues for targeting pathways involved in CAN initiation and progression. The aim of this review is to delineate the etiology of CAN in the context of a metabolic disorder characterized by elevated oxidative and inflammatory load.

Diet-dependent gut microbiota impacts on adult neurogenesis through mitochondrial stress modulation

The influence of dietary factors on brain health and mental function is becoming increasingly recognized. Similarly, mounting evidence supports a role for gut microbiota in modulating central nervous system function and behaviour. Still, the molecular mechanisms responsible for the impact of diet and associated microbiome in adult neurodegeneration are still largely unclear. In this study, we aimed to investigate whether and how changes in diet-associated microbiome and its metabolites impact on adult neurogenesis. Mice were fed a high-fat, choline-deficient diet, developing obesity and several features of the metabolic syndrome, including non-alcoholic steatohepatitis. Strikingly, our results showed, for the first time, that animals fed with this specific diet display premature increased neurogenesis, possibly exhausting the available neural stem cell pool for long-term neurogenesis processes. The high-fat, choline-deficient diet further induced neuroinflammation, oxidative stress, synaptic loss and cell death in different regions of the brain. Notably, this diet-favoured gut dysbiosis in the small intestine and cecum, up-regulating metabolic pathways of short-chain fatty acids, such as propionate and butyrate and significantly increasing propionate levels in the liver. By dissecting the effect of these two specific short-chain fatty acids in vitro, we were able to show that propionate and butyrate enhance mitochondrial biogenesis and promote early neurogenic differentiation of neural stem cells through reactive oxygen species- and extracellular signal-regulated kinases 1/2-dependent mechanism. More importantly, neurogenic niches of high-fat, choline-deficient-fed mice showed increased expression of mitochondrial biogenesis markers, and decreased mitochondrial reactive oxygen species scavengers, corroborating the involvement of this mitochondrial stress-dependent pathway in mediating changes of adult neurogenesis by diet. Altogether, our results highlight a mitochondria-dependent pathway as a novel mediator of the gut microbiota–brain axis upon dietary influences.

Exercise augments the modulatory effects of vitamin E on pre-diabetes-induced aortopathy: a potential role of adiponectin

Background: We tested the hypothesis that vitamin E may protect against pre-diabetes-induced aortic injury (aortopathy), and exercise can augment the action of vitamin E.Material and methods: Rats were either fed with a high fat and fructose diet (HFD) (model group) or a standard laboratory chow (control group) for 15 weeks before being sacrificed. The three protective groups were treated with vitamin E (HFD + Vit E), swimming exercises (HFD + Ex), and vitamin E plus swimming exercises (HFD + VitE + Ex), respectively.Results: Aortopathy was developed in the model group as demonstrated by substantial tissue ultrastructural alterations, which were partially protected by vitamin E and effectively protected with vitamin E plus swim exercise. Also, swimming exercises significantly (p < .05) increased the modulatory effects of vitamin E on dyslipidemia, insulin resistance, blood pressure, oxidative stress, inflammation, leptin, and adiponectin, except coagulation and thrombosis.Conclusions: Swim exercise augments the protective effects of vitamin E in a pre-diabetic animal model.

Obesity and Age-Related Changes in the Brain of the Zucker Lepr fa/fa Rats

Metabolic syndrome (MetS) is an association between obesity, dyslipidemia, hyperglycemia, hypertension, and insulin resistance. A relationship between MetS and vascular dementia was hypothesized. The purpose of this work is to investigate brain microanatomy alterations in obese Zucker rats (OZRs), as a model of MetS, compared to their counterparts lean Zucker rats (LZRs). 12-, 16-, and 20-weeks-old male OZRs and LZRs were studied. General physiological parameters and blood values were measured. Immunochemical and immunohistochemical techniques were applied to analyze the brain alterations. The morphology of nerve cells and axons, astrocytes and microglia were investigated. The blood-brain barrier (BBB) changes occurring in OZRs were assessed as well using aquaporin-4 (AQP4) and glucose transporter protein-1 (GLUT1) as markers. Body weight gain, hypertension, hyperglycemia, and hyperlipidemia were found in OZRs compared to LZRs. In the frontal cortex and hippocampus, a decrease of neurons was noticeable in the older obese rats in comparison to their age-matched lean counterparts. In OZRs, a reduction of neurofilament immunoreaction and gliosis was observed. The BBB of older OZRs revealed an increased expression of AQP4 likely related to the development of edema. A down-regulation of GLUT1 was found in OZRs of 12 weeks of age, whereas it increased in older OZRs. The behavioral analysis revealed cognitive alterations in 20-week-old OZRs. Based on these results, the OZRs may be useful for understanding the mechanisms through which obesity and related metabolic alterations induce neurodegeneration.

Water extract from processed Polygonum multiflorum modulate gut microbiota and glucose metabolism on insulin resistant rats

Background

The incidence of insulin resistance (IR) has rapidly increased worldwide over the last 20 years, no perfect solution has yet been identified. Finding new therapeutic drugs will help improve this situation. As a traditional Chinese medicine, PPM (processed Polygonum multiflorum) has widely been used in the clinic. Recently, other clinical functions of PPM have been widely analyzed.

Results

Administration of the water extract from PPM decreased the level of FBG, TC, and TG, and increased the level of FGC, thereby reducing the IR index and improving IR. Furthermore, Western blot analysis revealed that PPM significantly increased GPR43 and AMPK expression when compared with the MOD group, and GPR43, AMPK were known as glucose metabolism-related proteins. In addition, treatment with PPM can restore the balance of gut microbiota by adjusting the relative abundance of bacteria both at the phylum and genus level, and these changes have been reported to be related to IR.

Methods

Sprague Dawley (SD) rats were fed a high-fat diet and were gavaged daily with either normal saline solution or PPM for 12 weeks. Major biochemical indexes, such as fasting blood glucose (FBG), fasting glucagon (FGC), total cholesterol (TC), and triglyceride (TG) were measured. Then the protein expression of adenosine 5′-monophosphate -activated protein kinase (AMPK) and G protein-coupled receptor 43 (GPR43) was evaluated by using Western blot analysis. Moreover, the composition of gut microbiota was assessed by analyzing 16S rRNA sequences.

Conclusions

Our findings showed that PPM reversed the increasing of FBG and the decreasing of IRI, PPM accelerated the expression of glucose metabolism-related proteins and regulated the intestinal microecological balance. Therefore, we hold the opinion that PPM may be an effective option for treating IR.

Hypertension and progressive supranuclear palsy

BACKGROUND

The epidemiologic evidence of whether hypertension is associated with Progressive Supranuclear Palsy (PSP) is inconsistent. The ENGENE-PSP case-control study determined various PSP risk factors including whether hypertension preceded PSP onset.

METHODS

Incident PSP cases per NINDS-PSP criteria and age-, sex-, race- matched controls were recruited from similar North American geographic areas. All study participants were administered standardized interviews to obtain data on demographics, medical history and medications.

STATISTICS

We used univariate and multivariate conditional logistic regression models to measure the associations between PSP and the following predictor variables: education level, hypertension, comorbid vascular conditions (diabetes mellitus and hyperlipidemia), and classes of anti-hypertensive medications using odds ratios and 95% confidence intervals.

RESULTS

There were significant associations seen between PSP and hypertension (OR: 1.569; 95% CI 1.129-2.181; p-value = 0.007), education level (OR: 0.733; 95% CI 0.637-0.843; p-value<0.001) and beta-blocker use (OR: 2.000; 95% CI 1.053-3.799; p-value = 0.034). However, in the multi-variate analysis hypertension (OR: 1.492; 95% CI 1.045-2.129; p-value = 0.027) and education level (OR: 0.730; 95% CI 0.633-0.841; p-value<0.001) were the only significant associations.

CONCLUSION

These results suggest that there is a modest, yet significant association between hypertension and PSP. Further studies will be needed to better understand the pathophysiological basis for this finding.

Anxiety disorders in childhood are associated with youth IL-6 levels: A mediation study including metabolic stress and childhood traumatic events

Anxiety disorders (ADs) are chronic conditions that often have their onset in childhood and adolescence. Inflammation and oxidative stress markers have been associated with the vulnerability to ADs, however it is not known if ADs in childhood can influence these biomarkers levels longitudinally. This study aims to investigate a possible association between ADs and serum levels of IL-10, IL-6, IL-1β, TNF-α, BDNF, and protein carbonyl content, assessed after 5 years of follow-up. Moreover, we studied possible mediators for these associations, including physical activity, metabolic markers and childhood trauma. From 240 individuals evaluated at baseline, 73 were re-evaluated in the follow-up. Psychiatric diagnoses were assessed with the K-SADS or the MINI and child trauma questionnaire (CTQ) to evaluate presence of trauma. We searched serum levels of IL-10, IL-6, IL-1β and TNF-α (flow cytometry), BDNF (sandwich-ELISA) and carbonyl content in proteins (PCC method). We found a significant direct association between ADs at baseline and log IL-6 (B = 0.34, S.E. = 0.11, p = 0.002) and between AD and log BDNF (B = -0.10, S.E. = 0.05, p = 0.033) five years later. Searching for possible mediators of these association, we found that levels of HDL-cholesterol (ΔB = -0.148) partially mediated the association between ADs and IL-6. No significant mediators were found in the association between ADs and BDNF. Moreover, this association is no longer significant after controlling for the presence of depression. Our results demonstrated that previous AD diagnosis was associated with higher levels of IL-6 in the follow-up evaluation, suggesting that the presence of anxiety in childhood could influence altered inflammatory markers.

Metabolic Syndrome in Patients with Non-alcoholic Fatty Liver Disease: A Community Based Cross-sectional study

Background

Non-alcoholic fatty liver disease (NAFLD) is the deposition of fat inside liver cells in the absence of secondary causes. It is considered as a hepatic complication of metabolic syndrome. The metabolic syndrome consists of dyslipidemia, hypertension, diabetes, and obesity. This study aims to determine the prevalence of metabolic syndrome in Nepalese patients with NAFLD from mid-Western part of Nepal.

Method

This was a descriptive cross-sectional study. Three different sites were chosen in and around Butwal sub-metropolitan city of Rupandehi district, Nepal. A one-day health camp for the screening of fatty liver disease by ultrasonography (USG) was conducted at these sites. Participants with fatty liver were then classified into three grades by USG and the presence of metabolic syndrome was assessed by the National Cholesterol Education Program Adult Treatment Panel III (NCEP-ATPIII) criteria.

Results

A total of 385 participants with NAFLD were evaluated. Presence of metabolic syndrome by NCEP-ATPIII criteria was found to be in 57.6% participants; whereas, at least one component of metabolic syndrome was found in 91.4% of participants with radiologic features of fatty liver. Higher proportion of patients with NAFLD were males. Increased waist circumference followed by low high-density lipoprotein (HDL) level were the most common components of metabolic syndrome in participants with NAFLD.

Conclusions

Metabolic syndrome is common in Nepalese community patients with NAFLD.

The impact of exenatide (a GLP-1 agonist) on markers of inflammation and oxidative stress in normal human astrocytes subjected to various glycemic conditions

GLP-1 agonists such as exenatide and liraglutide are novel drugs for the treatment of diabetes and obesity. While improvements in glycemic control can rely on an incretin effect, the mechanisms behind the loss of weight following therapy have yet to be completely elucidated, and seem to be associated with alterations in eating habits, resulting from changes in cytokines e.g. interleukin 1β (IL-1β) and oxidative signaling in the central nervous system (CNS). Increased levels of IL-1β and reactive oxygen species have been demonstrated to exert anorexigenic properties, and astrocytes appear to actively participate in maintaining the integrity of the CNS, which includes the paracrine secretion of inflammatory cytokines and involvement in the redox status. Therefore, the present study decided to explore the influence of exenatide [a glucagon-like peptide 1 (GLP-1 agonist)] on inflammatory and oxidative stress markers in cultured human astrocytes as a potential target for weight reduction therapies. In an experimental setting, normal human astrocytes were subjected to various glycemic conditions, including 40 mg/dl-hypoglycemic, 100 mg/dl-normoglycemic and 400 mg/dl-hyperglycemic, and exenatide, which is a GLP-1 agonist. The involvement of intracellular signaling by a protein kinase A (PKA) in the action of exenatide was estimated using a specific PKA inhibitor-PKI (14-22). The expression levels of IL-1β, nuclear factor kappa κB (NFκB), glial-fibrillary acidic protein (GFAP), p22 NADPH oxidase, glutathione peroxidase, catalase, superoxide dismutase 1, and reactive oxidative species were measured. The present study demonstrated that varying glucose concentrations in the culture media did not affect the protein expression or the level of reactive oxygen species. Conversely, exenatide led to an increase in IL-1β in normoglycemic culture conditions, which was accompanied by the increased expression of p22, glutathione peroxidase and the reduced expression of GFAP. Changes in the expression of IL-1β and p22 were dependent on the activation of PKA. The present study concluded that exenatide predominantly affected astrocytes in normoglycemic conditions, and hypothesize that this impact demonstrated one of novel mechanisms associated with astrocyte signaling that may contribute to weight loss.

6-Hydroxydopamine induces different mitochondrial bioenergetics response in brain regions of rat

Mitochondrial dysfunction has been demonstrated to have a central role in Parkinson Disease (PD) pathophysiology. Some studies have indicated that PD causes an impairment in mitochondrial bioenergetics; however, the effects of PD on brain-region specific bioenergetics was never investigated before. This study aimed to evaluate mitochondrial bioenergetics in different rat brain structures in an in vitro model of PD using 6-OHDA. Rat brain slices of hippocampus, striatum, and cortex were exposed to 6-OHDA (100 μM) for 1 h and mitochondrial bioenergetic parameters, peroxide production, lactate dehydrogenase (LDH) and citrate synthase (CS) activities were analyzed. Hippocampus slices exposed to 6-OHDA presented increased peroxide production but, no mitochondrial adaptive response against 6-OHDA damage. Cortex slices exposed to 6-OHDA presented increased oxygen flux related to oxidative phosphorylation and energetic pathways exchange demonstrated by the increase in LDH activity, suggesting a mitochondrial compensatory response. Striatum slices exposed to 6-OHDA presented a decrease of oxidative phosphorylation and decrease of oxygen flux related to ATP-synthase indicating an impairment in the respiratory chain. The co-incubation of 6-OHDA with n-acetylcysteine (NAC) abolished the effects of 6-OHDA on mitochondrial function in all brain regions tested, indicating that the increased reactive oxygen species (ROS) production is responsible for the alterations observed in mitochondrial bioenergetics. The present results indicate a brain-region specific response against 6-OHDA, providing new insights into brain mitochondrial bioenergetic function in PD. These findings may contribute to the development of future therapies with a target on energy metabolism.