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An estimated 9% of the American population experiences type II diabetes mellitus (T2DM) due to diet or genetic predisposition. Recent reports indicate that patients with T2DM are at increased risk for cognitive dysfunctions, as observed in conditions like Alzheimer's disease (AD). In addition, AD is the leading cause of dementia, highlighting the urgency of developing novel therapeutic targets for T2DM-induced cognitive deficits. The peroxisome proliferator activated receptor-δ (PPAR-δ) is highly expressed in the brain and has been shown to play an important role in spatial memory and hippocampal neurogenesis. However, the effect of PPAR-δ agonists on T2DM-induced cognitive impairment has not been explored. In this study, the effects of GW0742 (a selective PPAR-δ agonist) on hippocampal synaptic transmission, plasticity, and spatial memory were investigated in the db/db mouse model of T2DM. Oral administration of GW0742 for 2 weeks significantly improved hippocampal long-term potentiation. In addition, GW0742 effectively prevented deficits in hippocampal dependent spatial memory in db/db mice. PPAR-δ-mediated improvements in synaptic plasticity and behavior were accompanied by a significant recovery in hippocampal α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor-mediated synaptic transmission. Our findings suggest that activation of PPAR-δ might ameliorate T2DM-induced impairments in hippocampal synaptic plasticity and memory.

Peroxisome proliferator-activated receptors (PPARs) are ligand-activated transcription factors of the nuclear hormone receptor superfamily comprising three subtypes: PPARα, PPARγ, and PPARβ/δ. The PPAR family of nuclear receptors is centrally involved in regulating whole-body energy homeostasis and metabolic function. Endogenous ligands include free fatty acids, eicosanoids, and leukotrienes. Synthetic ligands developed to serve as full agonists aim at treating diabetes type 2, hyperlipidemia, and other metabolic-related diseases. Further, there has been a developing interest in the role of PPAR agonist’s role in neurodegenerative disease. However, many of these clinically practical therapeutics are associated with harmful effects on human health. Therefore, new approaches have led to a new class of selective PPAR modulators (SPARMs), or partial agonists meet this challenge. In addition, these partial agonists have been observed to show a favorable impact on insulin sensitivity, blood glucose levels, and dyslipidemia with significantly reduced side effects on human health. Partial agonists have been found to display differences in transcriptional and cellular outcomes by acting through distinct structural and dynamic mechanisms within the ligand-binding region when compared to full agonists. Recently, a new focus on PPAR agonists’ class has intensified for neurodegenerative diseases, as new ligands and novel biological roles have emerged particularly for its therapeutic potential in Alzheimer’s disease (AD). The present chapter critically analyzes current PPAR ligands using in silico modeling and the implication of promising new therapeutics in neurodegenerative disorders.

Diabetes mellitus exists as a comorbidity with congestive heart failure (CHF). However, the exact molecular signaling mechanism linking CHF as the major form of mortality from diabetes remains unknown. Type 2 diabetic patients display abnormally high levels of metabolic products associated with gut dysbiosis. One such metabolite, trimethylamine N-oxide (TMAO), has been observed to be directly related with increased incidence of cardiovascular diseases (CVD) in human patients. TMAO a gut-liver metabolite, comes from the metabolic degenerative product trimethylamine (TMA) that is produced from gut microbial metabolism. Elevated levels of TMAO in diabetics and obese patients are observed to have a direct correlation with increased risk for major adverse cardiovascular events. The pro-atherogenic effect of TMAO is attributed to enhancing inflammatory pathways with cholesterol and bile acid dysregulation, promoting foam cell formation. Recent studies have revealed several potential therapeutic strategies for reducing TMAO levels and will be the central focus for the current review. However, few have focused on developing rational drug therapeutics and may be due to the gaps in knowledge for understanding the mechanism by which microbial TMA producing enzymes and hepatic flavin-containing monoxygenase (FMO) can work together in preventing elevation of TMAO levels. Therefore, it is critical to understand the advantages of developing a novel rational drug design strategy that manipulates FMO production of TMAO and TMA production by microbial enzymes. This review will focus on the inspection of FMO manipulation, as well as gut microbiota dysbiosis and its influence on metabolic disorders including cardiovascular disease and describe novel potential pharmacological therapeutic development.

Aims Inflammation is considered to be one of the crucial pathological factors associated with the development of Alzheimer's disease, although supportive experimental evidence remains undiscovered. Therefore, the current study was carried out to better understand and establish the pathophysiological involvement of chronic inflammation in a double transgenic mouse model of Alzheimer's disease. Main methods We analyzed amyloid-beta deposition, oxidative stress, biochemical, neurochemical and immunological markers in a 10 month old (APΔE9) mouse model. Memory functions were assessed by behavioral testing followed by measurement of synaptic plasticity via extracellular field recordings. Key findings Substantial increases in amyloid-beta levels, beta-secretase activity, and oxidative stress, along with significant neurochemical alterations in glutamate and GABA levels were detected in the brain of APΔE9 mice. Interestingly, marked elevations of pro-inflammatory cytokines in whole brain lysate of APΔE9 mice were observed. Flow cytometric analysis revealed a higher frequency of CD4 + IL-17a and IFN-γ secreting T-cells in APΔE9 brain, indicating a robust T-cell infiltration and activation. Behavioral deficits in learning and memory tasks, along with impairment in long-term potentiation and associated biochemical changes in the expression of glutamatergic receptor subunits were evident. Significance Thus, this study establishes the role by which oxidative stress, alterations in glutamate and GABA levels and inflammation increases hippocampal and cortical neurotoxicity resulting in the cognitive deficits associated with Alzheimer's disease.

Duchenne Muscular Dystrophy (DMD) is associated with progressive cardiac pathology; however, the SIRT1/PGC1-α activator quercetin may cardioprotect dystrophic hearts. We tested the extent to which long-term 0.2% dietary quercetin enrichment attenuates dystrophic cardiopathology in Mdx/Utrn+/− mice. At 2 mo, Mdx/Utrn+/− mice were fed quercetin-enriched (Mdx/Utrn+/−-Q) or control diet (Mdx/Utrn+/−) for 8 mo. Control C57BL/10 (C57) animals were fed a control diet for 10 mo. Cardiac function was quantified by MRI at 2 and 10 mo. Spontaneous physical activity was quantified during the last week of treatment. At 10 mo hearts were excised for histological and biochemical analysis. Quercetin feeding improved various physiological indexes of cardiac function in diseased animals. Mdx/Utrn+/−-Q also engaged in more high-intensity physical activity than controls. Histological analyses of heart tissues revealed higher expression and colocalization of utrophin and α-sarcoglycan. Lower abundance of fibronectin, cardiac damage (Hematoxylin Eosin-Y), and MMP9 were observed in quercetin-fed vs. control Mdx/Utrn+/− mice. Quercetin evoked higher protein abundance of PGC-1α, cytochrome c, ETC complexes I–V, citrate synthase, SOD2, and GPX compared with control-fed Mdx/Utrn+/−. Quercetin decreased abundance of inflammatory markers including NFκB, TGF-β1, and F4/80 compared with Mdx/Utrn+/−; however, P-NFκB, P-IKBα, IKBα, CD64, and COX2 were similar between groups. Dietary quercetin enrichment improves cardiac function in aged Mdx/Utrn+/− mice and increases mitochondrial protein content and dystrophin glycoprotein complex formation. Histological analyses indicate a marked attenuation in pathological cardiac remodeling and indicate that long-term quercetin consumption benefits the dystrophic heart. NEW & NOTEWORTHY The current investigation provides first-time evidence that quercetin provides physiological cardioprotection against dystrophic pathology and is associated with improved spontaneous physical activity. Secondary findings suggest that quercetin-dependent outcomes are in part due to PGC-1α pathway activation.

Rahul Rajesh Amin, Rohin Patel, Prashant Bamania Faculty of Medicine, Imperial College London, Kensington, London, UnitedKingdomWe read with great interest the study by McKenzie et al,1 which explores the impact of providing feedback to students on their ability to carry out a clinical procedure. This study was particularly interesting to us as fifth-year medical students at Imperial College London who have learnt several clinical skills during rotations. A noteworthy finding was that education involving providing feedback to students had a positive impact on their performance.1 Furthermore, the recommendation that clinical skills training be accompanied with feedback resonated strongly with us.Authors’ replySusan McKenzie1 Annette Burgess2 Craig Mellis11Central Clinical School, 2Education Office, Sydney Medical School, The University of Sydney, Sydney, NSW, AustraliaThank you for the opportunity to respond to the letter by Dr Amin and colleagues. We wish to thank Dr Amin and colleagues for their interest in our recent article1 and have found their feedback encouraging for our work. We find the use of electronic feedback to be of particular interest as we are currently developing a similar electronic application for the use of students’ “smart phones”. We anticipate by capturing feedback in this manner, students have a great opportunity to reflect on their procedural skills performance, and to be able to improve their skills when necessary.View the original paper by McKenzie and colleagues.

Alzheimer’s disease (AD) is a chronic neurodegenerative disease characterized by abnormal protein accumulation, synaptic dysfunction, and cognitive impairment. The continuous increase in the incidence of AD with the aged population and mortality rate indicates the urgent need for establishing novel molecular targets for therapeutic potential. Peroxisome proliferator-activated receptor gamma (PPARγ) agonists such as rosiglitazone and pioglitazone reduce amyloid and tau pathologies, inhibit neuroinflammation, and improve memory impairments in several rodent models and in humans with mild-to-moderate AD. However, these agonists display poor blood brain barrier permeability resulting in inadequate bioavailability in the brain and thus requiring high dosing with chronic time frames. Furthermore, these dosing levels are associated with several adverse effects including increased incidence of weight gain, liver abnormalities, and heart failure. Therefore, there is a need for identifying novel compounds which target PPARγ more selectively in the brain and could provide therapeutic benefits without a high incidence of adverse effects. This review focuses on how PPARγ agonists influence various pathologies in AD with emphasis on development of novel selective PPARγ modulators.

Adiponectin, the most abundant plasma adipokine, plays an important role in the regulation of glucose and lipid metabolism. Adiponectin also possesses insulin-sensitizing, anti-inflammatory, angiogenic, and vasodilatory properties which may influence central nervous system (CNS) disorders. Although initially not thought to cross the blood-brain barrier, adiponectin enters the brain through peripheral circulation. In the brain, adiponectin signaling through its receptors, AdipoR1 and AdipoR2, directly influences important brain functions such as energy homeostasis, hippocampal neurogenesis, and synaptic plasticity. Overall, based on its central and peripheral actions, recent evidence indicates that adiponectin has neuroprotective, antiatherogenic, and antidepressant effects. However, these findings are not without controversy as human observational studies report differing correlations between plasma adiponectin levels and incidence of CNS disorders. Despite these controversies, adiponectin is gaining attention as a potential therapeutic target for diverse CNS disorders, such as stroke, Alzheimer’s disease, anxiety, and depression. Evidence regarding the emerging role for adiponectin in these disorders is discussed in the current review.

Honokiol (poly-phenolic lignan from Magnolia grandiflora) is a Sirtuin-3 (SIRT3) activator which exhibit antioxidant activity and augment mitochondrial functions in several experimental models. Modern evidence suggests the critical role of SIRT3 in the progression of several metabolic and neurodegenerative diseases. Amyloid beta (Aβ), the precursor to extracellular senile plaques, accumulates in the brains of patients with Alzheimer's disease (AD) and is related to the development of cognitive impairment and neuronal cell death. Aβ is generated from amyloid-β precursor protein (APP) through sequential cleavages, first by β-secretase and then by γ-secretase. Drugs modulating this pathway are believed to be one of the most promising strategies for AD treatment. In the present study, we found that Honokiol significantly enhanced SIRT3 expression, reduced reactive oxygen species generation and lipid peroxidation, enhanced antioxidant activities, and mitochondrial function thereby reducing Aβ and sAPPβ levels in Chinese Hamster Ovarian (CHO) cells (carrying the amyloid precursor protein-APP and Presenilin PS1 mutation). Mechanistic studies revealed that Honokiol affects neither protein levels of APP nor α-secretase activity. In contrast, Honokiol increased the expression of AMPK, CREB, and PGC-1α, thereby inhibiting β-secretase activity leading to reduced Aβ levels. These results suggest that Honokiol is an activator of SIRT3 capable of improving antioxidant activity, mitochondrial energy regulation, while decreasing Aβ, thereby indicating it to be a lead compound for AD drug development.

Adiponectin has been reported to exert protective effects during pathological ventricular remodeling, but the role of adiponectin in volume overload-induced heart failure remains unclear. In this study we investigated the effect of adiponectin on cardiac myocyte contractile dysfunction following volume overload in rats.Volume overload was surgically induced in rats by infrarenal aorta-vena cava fistula. The rats were intravenously administered adenoviral adiponectin at 2-, 6- and 9-weeks following fistula. The protein expression of adiponectin, adiponectin receptors (AdipoR1/R2 and T-cadherin) and AMPK activity were measured using Western blot analyses. Isolated ventricular myocytes were prepared at 12 weeks post-fistula to examine the contractile performance of myocytes and intracellular Ca(2+) transient.A-V fistula resulted in significant reductions in serum and myocardial adiponectin levels, myocardial adiponectin receptor (AdipoR1/R2 and T-cadherin) levels, as well as myocardial AMPK activity. Consistent with these changes, the isolated myocytes exhibited significant depression in cell shortening and intracellular Ca(2+) transient. Administration of adenoviral adiponectin significantly increased serum adiponectin levels and prevented myocyte contractile dysfunction in fistula rats. Furthermore, pretreatment of isolated myocytes with recombinant adiponectin (2.5 μg/mL) significantly improved their contractile performance in fistula rats, but had no effects in control or adenoviral adiponectin-administered rats.These results demonstrate a positive correlation between adiponectin downregulation and volume overload-induced ventricular remodeling. Adiponectin plays a protective role in volume overload-induced heart failure.

Doxorubicin (DOX) is a highly effective anti-neoplastic agent; however, its cumulative dosing schedules are clinically limited by the development of cardiotoxicity. Previous studies have attributed the cause of DOX-mediated cardiotoxicity to mitochondrial iron accumulation and the ensuing reactive oxygen species (ROS) formation. The present study investigates the role of frataxin (FXN), a mitochondrial iron-sulfur biogenesis protein, and its role in development of DOX-mediated mitochondrial dysfunction. Athymic mice treated with DOX (5 mg/kg, 1 dose/wk with treatments, followed by 2-wk recovery) displayed left ventricular hypertrophy, as observed by impaired cardiac hemodynamic performance parameters. Furthermore, we also observed significant reduction in FXN expression in DOX-treated animals and H9C2 cardiomyoblast cell lines, resulting in increased mitochondrial iron accumulation and the ensuing ROS formation. This observation was paralleled in DOX-treated H9C2 cells by a significant reduction in the mitochondrial bioenergetics, as observed by the reduction of myocardial energy regulation. Surprisingly, similar results were observed in our FXN knockdown stable cell lines constructed by lentiviral technology using short hairpin RNA. To better understand the cardioprotective role of FXN against DOX, we constructed FXN overexpressing cardiomyoblasts, which displayed cardioprotection against mitochondrial iron accumulation, ROS formation, and reduction of mitochondrial bioenergetics. Lastly, our FXN overexpressing cardiomyoblasts were protected from DOX-mediated cardiac hypertrophy. Together, our findings reveal novel insights into the development of DOX-mediated cardiomyopathy.

Interleukin-6 (IL-6) is a pleiotropic cytokine that protects against cardiac ischemia-reperfusion (I/R) injury following pharmacological and ischemic preconditioning (IPC), but the affiliated role in exercise preconditioning is unknown. Our study purpose was to characterize exercise-induced IL-6 cardiac signaling ( aim 1) and evaluate myocardial preconditioning ( aim 2). In aim 1, C57 and IL-6−/− mice underwent 3 days of treadmill exercise for 60 min/day at 18 m/min. Serum, gastrocnemius, and heart were collected preexercise, immediately postxercise, and 30 and 60 min following the final exercise session and analyzed for indexes of IL-6 signaling. For aim 2, a separate cohort of exercise-preconditioned (C57 EX and IL-6−/− EX) and sedentary (C57 SED and IL-6−/− SED) mice received surgical I/R injury (30 min I, 120 min R) or a time-matched sham operation. Ischemic and perfused tissues were examined for necrosis, apoptosis, and autophagy. In aim 1, serum IL-6 and IL-6 receptor (IL-6R), gastrocnemius, and myocardial IL-6R were increased following exercise in C57 mice only. Phosphorylated (p) signal transducer and activator of transcription 3 was increased in gastrocnemius and heart in C57 and IL-6−/− mice postexercise, whereas myocardial iNOS and cyclooxygenase-2 were unchanged in the exercised myocardium. Exercise protected C57 EX mice against I/R-induced arrhythmias and necrosis, whereas arrhythmia score and infarct outcomes were higher in C57 SED, IL-6−/− SED, and IL-6−/− EX mice compared with SH. C57 EX mice expressed increased p-p44/42 MAPK (Thr202/Tyr204) and p-p38 MAPK (Thr180/Tyr182) compared with IL-6−/− EX mice, suggesting pathway involvement in exercise preconditioning. Findings indicate exercise exerts cardioprotection via IL-6 and strongly implicates protective signaling originating from the exercised skeletal muscle.

New Findings What is the central question of this study? Does the δ-opioid receptor trigger exercise-induced cardioprotection against ischaemia–reperfusion injury? What is the main finding and its importance? In exercised hearts, the δ-opioid receptor appears to trigger cardioprotection against ischaemia–reperfusion-induced tissue necrosis but not apoptosis. Abstract Endogenous opioids mediate exercise-induced cardioprotection against ischaemia–reperfusion (IR) injury, although the opioid receptor subtype mediating this effect is unknown. We investigated whether the δ-opioid receptor mediates exercise-induced cardioprotection against IR injury. Endogenous opioids are produced in various tissues, including the heart and skeletal muscle; therefore, we also sought to identify the effect of exercise on circulating endogenous opioid as well as transcript, protein and receptor expression in heart and skeletal muscle. Male Sprague–Dawley rats (n = 73) were assigned randomly to treadmill exercise or sedentary treatments. Cardiac tissue and serum were harvested 0, 20 and 120 min following exercise and from sedentary animals (n = 32) to quantify effects on proenkephalin and δ-opioid receptor mRNA and protein levels, as well as serum enkephalin. Skeletal muscle (soleus) was harvested at identical time points for determination of proenkephalin protein and mRNA. A separate group of rats (n = 41) were randomly assigned to sham operation (Sham; surgical control), sedentary (Sed), exercise (Ex) or exercise + δ-opioid receptor antagonist (ExD; naltrindole, 5 mg kg−1 i.p.) and received IR by left anterior descending coronary artery ligation in vivo. After IR, tissues were harvested to quantify treatment effects on necrosis and apoptosis. Cardiac proenkephalin mRNA expression increased following exercise (0 min, P = 0.03; 120 min, P = 0.021), while soleus expression was unaffected. Exercise-induced changes in serum enkephalin were undetectable. After IR, tissue necrosis was elevated in Sed and ExD hearts (P

New Findings What is the central question of this study? Does dietary quercetin enrichment improve biochemical and histological outcomes in hearts from mdx mice? What is the main finding and what is its importance? Biochemical and histological findings suggest that chronic quercetin feeding of mdx mice may improve mitochondrial function and attenuate tissue pathology. Patients with Duchenne muscular dystrophy suffer from cardiac pathology, which causes up to 40% of all deaths because of fibrosis and cardiac complications. Quercetin is a flavonol with anti-inflammatory and antioxidant effects and is also an activator of peroxisome proliferator-activated receptor γ coactivator 1α capable of antioxidant upregulation, mitochondrial biogenesis and prevention of cardiac complications. We sought to determine the extent to which dietary quercetin enrichment prevents (experiment 1) and rescues cardiac pathology (experiment 2) in mdx mice. In experiment 1, 3-week-old mdx mice were fed control chow (C3w6m, n = 10) or chow containing 0.2% quercetin for 6 months (Q3w6m, n = 10). In experiment 2, 3-month-old mdx mice were fed control chow (C3m6m, n = 10) or 0.2% chow containing 0.2% quercetin for 6 months (Q3m6m, n = 10). Hearts were excised for histological and biochemical analyses. In experiment 1, Western blot targets for mitochondrial biogenesis (cytochrome c, P = 0.007) and antioxidant expression (superoxide dismutase 2, P = 0.014) increased in Q3w6m mice compared with C3w6m. Histology revealed increased utrophin (P = 0.025) and decreased matrix metalloproteinase 9 abundance (P = 0.040) in Q3w6m mice compared with C3w6m. In experiment 2, relative (P = 0.023) and absolute heart weights (P = 0.020) decreased in Q3m6m mice compared with C3m6m. Indications of damage (Haematoxylin- and Eosin-stained sections, P = 0.007) and Western blot analysis of transforming growth factor β1 (P = 0.009) were decreased in Q3m6m mice. Six months of quercetin feeding increased a mitochondrial biomarker, antioxidant protein and utrophin and decreased matrix metalloproteinase 9 in young mice. Given that these adaptations are associated with attenuated cardiac pathology and damage, the present findings may indicate that dietary quercetin enrichment attenuates dystrophic cardiac pathology, but physiological confirmation is needed.

Previous studies from our group have demonstrated that sevoflurane post-conditioning (SPC) protects against myocardial ischemia reperfusion injury via elevating the intranuclear expression of hypoxia inducible factor-1 alpha (HIF-1α). However, diabetic SPC is associated with decreased myocardial protection and disruption of the HIF-1 signaling pathway. Previous studies have demonstrated that cobalt chloride (CoCl2) can upregulate HIF-1α expression under diabetic conditions, but whether myocardial protection by SPC can be restored afterward remains unclear. We established a rat model of type 2 diabetes and a Langendorff isolated heart model of ischemia-reperfusion injury. Prior to reperfusion, 2.4% sevoflurane was used as a post-conditioning treatment. The diabetic rats were treated with CoCl2 24 h before the experiment. At the end of reperfusion, tests were performed to assess myocardial function, infarct size, mitochondrial morphology, nitric oxide (NO), Mitochondrial reactive oxygen species (ROS), mitochondrial respiratory function and enzyme activity, HIF-1α, vascular endothelial growth factor (VEGF) and endothelial NO synthase (eNOS) protein levels. In addition, myocardial protection by SPC was monitored after the blood glucose levels were lowered by insulin. The diabetic state was associated with deficient SPC protection and decreased HIF-1α expression. After treating the diabetic rats with CoCl2, SPC significantly upregulated the expression of HIF-1α, VEGF and eNOS, which markedly improved cardiac function, NO, mitochondrial respiratory function, and enzyme activity and decreased the infarction areas and ROS. In addition, these effects were not influenced by blood glucose levels. This study proved that CoCl2activates the HIF-1α signaling pathway, which restores SPC-dependent myocardial protection under diabetic conditions, and the protective effects of SPC were independent of blood glucose levels.

Background Increased consumption of omega-3 (ω-3) fatty acids found in cold-water fish and fish oil has been reported to protect against obesity. A potential mechanism may be through reduction in adipocyte differentiation. Stearidonic acid (SDA), a plant-based ω-3 fatty acid, has been targeted as a potential surrogate for fish-based fatty acids; however, its role in adipocyte differentiation is unknown. This study was designed to evaluate the effects of SDA on adipocyte differentiation in 3T3-L1 cells. Methods 3T3-L1 preadipocytes were differentiated in the presence of SDA or vehicle-control. Cell viability assay was conducted to determine potential toxicity of SDA. Lipid accumulation was measured by Oil Red O staining and triglyceride (TG) quantification in differentiated 3T3-L1 adipocytes. Adipocyte differentiation was evaluated by adipogenic transcription factors and lipid accumulation gene expression by quantitative real-time polymerase chain reaction (qRT-PCR). Fatty acid analysis was conducted by liquid chromatography-mass spectrometry/mass spectrometry (LC-MS/MS). Results 3T3-L1 cells treated with SDA were viable at concentrations used for all studies. SDA treatment reduced lipid accumulation in 3T3-L1 adipocytes. This anti-adipogenic effect by SDA was a result of down-regulation of mRNA levels of the adipogenic transcription factors CCAAT/enhancer-binding proteins alpha and beta (C/EBPα, C/EBPβ), peroxisome proliferator-activated receptor gamma (PPARγ), and sterol-regulatory element binding protein-1c (SREBP-1c). SDA treatment resulted in decreased expression of the lipid accumulation genes adipocyte fatty-acid binding protein (AP2), fatty acid synthase (FAS), stearoyl-CoA desaturase (SCD-1), lipoprotein lipase (LPL), glucose transporter 4 (GLUT4) and phosphoenolpyruvate carboxykinase (PEPCK). The transcriptional activity of PPARγ was found to be decreased with SDA treatment. SDA treatment led to significant EPA enrichment in 3T3-L1 adipocytes compared to vehicle-control. Conclusion These results demonstrated that SDA can suppress adipocyte differentiation and lipid accumulation in 3T3-L1 cells through down-regulation of adipogenic transcription factors and genes associated with lipid accumulation. This study suggests the use of SDA as a dietary treatment for obesity. Electronic supplementary material The online version of this article (10.1186/s12944-017-0574-7) contains supplementary material, which is available to authorized users.

The World Health Organization and the National Institute of Mental Health (United States of America) states that neurodegenerative diseases leads to significant loss of regular activity of the patients, their family and the caretakers leading to a huge economic loss. Current treatments provide modest and temporary symptomatic relief, without altering the underlying mechanisms associated with the onset and the progression of the neurodegenerative diseases. Strong scientific evidence points to the involvement of oxidative stress in the pathogenesis of neurodegenerative diseases. Thus, the current therapeutic efforts have been directed to find beneficial agents that could reduce the oxidative damage and promote a functional recovery of neurons in degenerative disorders. Hydrogen peroxide is an endogenous neurotoxin which can initiate and propagate (promote) neurodegeneration. Hibiscus sabdariffa (roselle) exhibits multiple pharmacological activities. Hence in this study, the authors evaluated the neuroprotective effects and the possible mechanisms of action of Hibiscus sabdariffa (roselle) against the hydrogen peroxide-induced neurotoxicity. Hibiscus sabdariffa exhibited antioxidant and antiapoptotic effects and significantly attenuated the neurotoxicity of hydrogen peroxide. Hibiscus sabdariffa exhibits neuroprotective effects and can be an effective and novel alternative approach to reduce the risk of various neurodegenerative disorders.

Patients with diabetes exhibit significantly altered renin-angiotensin system (RAS) control. Recently, it has been determined that hyperglycemic conditions induce an increase in angiotensin II (AT II) expression; specifically by cardiomyocytes. Altered RAS has been shown to be associated with an increase in oxidative stress and cardiac dysfunction leading to the development of cardiac hypertrophy. The transient outward potassium current (I(to)) in cardiac myocytes is mainly mediated by members of the Kv subfamily of voltage gated potassium channels and has been shown to be altered in cellular localization and expression during the development of cardiac hypertrophy. However it is not clear as to how AT II affects the pore forming complex at the cell membrane and thus directly affects the I(to) current. In the current study, we explored the protective effect of PPARγ ligands on cardiomyocyte I(to) by preventing NADPH Oxidase activation and the ensuing ROS formation. Furthermore, short term PPARγ activation in diabetic leptin deficient db/db mice displayed improvements in the membrane association of the molecular components of I(to) as well as prolonged QT interval. These findings demonstrate that PPARγ agonists have the potential to attenuate cardiomyocyte dysfunction associated with diabetes.

Elevated blood branched-chain amino acids (BCAA) are often associated with insulin resistance and type 2 diabetes, which might result from a reduced cellular utilization and/or incomplete BCAA oxidation. White adipose tissue (WAT) has become appreciated as a potential player in whole body BCAA metabolism. We tested if expression of the mitochondrial BCAA oxidation checkpoint, branched-chain α-ketoacid dehydrogenase (BCKD) complex, is reduced in obese WAT and regulated by metabolic signals. WAT BCKD protein (E1α subunit) was significantly reduced by 35–50% in various obesity models ( fa/fa rats, db/db mice, diet-induced obese mice), and BCKD component transcripts significantly lower in subcutaneous (SC) adipocytes from obese vs. lean Pima Indians. Treatment of 3T3-L1 adipocytes or mice with peroxisome proliferator-activated receptor-γ agonists increased WAT BCAA catabolism enzyme mRNAs, whereas the nonmetabolizable glucose analog 2-deoxy-d-glucose had the opposite effect. The results support the hypothesis that suboptimal insulin action and/or perturbed metabolic signals in WAT, as would be seen with insulin resistance/type 2 diabetes, could impair WAT BCAA utilization. However, cross-tissue flux studies comparing lean vs. insulin-sensitive or insulin-resistant obese subjects revealed an unexpected negligible uptake of BCAA from human abdominal SC WAT. This suggests that SC WAT may not be an important contributor to blood BCAA phenotypes associated with insulin resistance in the overnight-fasted state. mRNA abundances for BCAA catabolic enzymes were markedly reduced in omental (but not SC) WAT of obese persons with metabolic syndrome compared with weight-matched healthy obese subjects, raising the possibility that visceral WAT contributes to the BCAA metabolic phenotype of metabolically compromised individuals.

Type 2 diabetes is at epidemic proportions and thus development of novel pharmaceutical therapies for improving insulin sensitivity has become of paramount importance. The objectives of the current study were to develop novel dual PPARγ/δ agonists without the deleterious side effects associated with full PPARγ agonists. Docking simulations of 23 novel compounds within the ligand binding domain of PPARγ/δ were performed using AutoDock Vina which consistently reproduced experimental binding poses from known PPAR agonists. Comparisons were made and described with other docking programs AutoDock and Surflex-Dock (from SYBYL-X). Biological evaluation of compounds was accomplished by transcriptional promoter activity assays, quantitative PCR gene analysis for known PPARγ/δ targets as well as in vitro assays for lipid accumulation and mitochondrial biogenesis verses known PPAR agonists. We found one (compound 9) out of the 23 compounds evaluated, to be the most potent and selective dual PPARγ/δ agonist which did not display the deleterious side effects associated with full PPARγ agonists.

Exercise is a potent stimulus against cardiac ischemia reperfusion (IR) injury, although the protective mechanisms are not completely understood. The study purpose was to examine whether the mitochondrial or sarcolemmal ATP-sensitive potassium channel (mito KATPor sarc KATP, respectively) mediates exercise-induced cardioprotection against post-IR cell death and apoptosis. Eighty-six, 4-mo-old male Sprague Dawley rats were randomly assigned to treadmill exercise (Ex; 30 m/min, 3 days, 60 min, ∼70 maximal oxygen uptake) and sedentary (Sed) treatments. Rats were exposed to regional cardiac ischemia (50 min) and reperfusion (120 min) or Sham (170 min; no ligation) surgeries. Exercise subgroups received placebo (saline), 5-hydroxydecanoate (5HD; 10 mg/kg ip), or HMR1098 (10 mg/kg ip) to inhibit mito KATPor sarc KATPchannel. Comprehensive outcome assessments included post-IR ECG arrhythmias, cardiac tissue necrosis, redox perturbations, and autophagy biomarkers. No arrhythmia differences existed between exercised and sedentary hearts following extended-duration IR ( P < 0.05). The sarc KATPchannel was confirmed essential ( P = 0.002) for prevention of antinecrotic tissue death with exercise (percent infarct, Sed = 42%; Ex = 20%; Ex5HD = 16%; ExHMR = 42%), although neither the mito KATP( P = 0.177) nor sarc KATP( P = 0.274) channel provided post-IR protection against apoptosis (terminal deoxynucleotidyl transferase deoxy UTP-mediated nick-end labeling-positive nuclei/mm2, Sham = 1.8 ± 0.5; Sed = 19.4 ± 6.7; Ex = 7.5 ± 4.6; Ex5HD = 14.0 ± 3.9; ExHMR = 11.1 ± 1.8). Exercise preconditioning also appears to preserve basal autophagy levels, as assessed by Beclin 1 ( P ≤ 0.001), microtubule-associated protein-1 light-chain 3B ratios ( P = 0.020), and P62 ( P ≤ 0.001), in the hours immediately following IR. Further research is needed to better understand these findings and corresponding redox changes in exercised hearts.

Rahul Rajesh Amin,Prashant Bamania Faculty of Medicine, Imperial College London, London, UKWe read with great interest the study by Van Wyk et al1 which explores the beliefs and opinions held by final-year medical students on the impact of gender on their training and the medical profession they were about to enter. As fifth year medical students ourselves, studying at Imperial College London, UK, this was a study we could strongly relate to and as such, we were particularly impressed by some of the findings.Vieworiginalpaper by Van Wyk et al

The nuclear receptor peroxisome proliferator-activated receptor (PPAR)gamma plays a key role in regulating whole body glucose homeostasis and insulin sensitivity. Although it is expressed most highly in adipose, it is also present at lower levels in many tissues, including skeletal muscle. The role muscle PPARgamma plays in metabolic regulation and in mediating the antidiabetic effects of the thiazolidinediones is not understood. The goal of this work was to examine the molecular and physiological effects of PPARgamma activation in muscle cells. We found that pharmacological activation of PPARgamma in primary cultured myocytes, and genetic activation of muscle PPARgamma in muscle tissue of transgenic mice, induced the production of adiponectin directly from muscle cells. This muscle-produced adiponectin was functional and capable of stimulating adiponectin signaling in myocytes. In addition, elevated skeletal muscle PPARgamma activity in transgenic mice provided a significant protection from high-fat diet-induced insulin resistance and associated changes in muscle phenotype, including reduced myocyte lipid content and an increase in the proportion of oxidative muscle fiber types. Our findings demonstrate that PPARgamma activation in skeletal muscle can have a significant protective effect on whole body glucose homeostasis and insulin resistance and that myocytes can produce and secrete functional adiponectin in a PPARgamma-dependent manner. We propose that activation of PPARgamma in myocytes induces a local production of adiponectin that acts on muscle tissue to improve insulin sensitivity.

The electrophysiological hallmark of the failing heart is the prolongation of action potential duration that induces arrhythmia and sudden death. Depressed outward potassium currents (Ito) has been implicated as the major cause of altered action potential during ventricular remodeling. The molecular mechanism underlying depressed Ito in the diseased heart is still poorly understood. Recent studies have demonstrated that adiponectin (APN) has a cardio-protective effect in response to various pathological stimuli; however, little information is available regarding the potential effects of APN on electrophysiological remodeling under pathological conditions. The present study were to determine the effect of adiponectin treatment on ventricular potassium channel function in a rat model of volume overload induced heart failure. Volume-overload was induced by surgical creation of an infrarenal aorta-vena cava fistula. Rats were administrated with or without adenovirus-mediated overexpression of adiponectin (Ad-APN) at 2-, 5- and 8- weeks post-fistula. In vivo ECGs were used to evaluate changes in QT interval in rats at 10 weeks post-fistula. Ventricular myocytes were isolated at 10 weeks post-fistula. Western blots were used to measure cytoplasmic and membrane protein expression of potassium channels Kv4.2 and Kv 4.3, as well as, KChIP2. Whole cell patch clamp was used to evaluate action potential and Ito currents. Results showed that adiponectin levels in serum and myocytes were significantly reduced following fistula. The duration of action potential was prolonged in ventricular myocytes following 10-week fistula, which was correlated with the in vivo QT interval prolongation, as well as a depression of functional Ito and decreased protein expression of Ito channel subunits in ventricular myocytes. In vivo supplementation of Ad-APN increased the protein levels of Ito channel subunits and prevented Ito depression in ventricular myocytes following 10-week fistula. This further restored the duration of action potential and the QT interval on the ECG back to the normal. These results indicate that adiponectin was able to prevent volume overload-induced ventricular electrophysiological remodeling.

Previous studies have demonstrated the protective signaling of hypoxia-inducible factor (HIF)-1 α against ischemia-reperfusion (I/R) injury in the heart. In the present study, we provide further evidence for a cardioprotective mechanism by HIF-1α against I/R injury exerted via the mitochondrial protein frataxin, which regulates mitochondrial Fe-S cluster formation. Disruption of frataxin has been found to induce mitochondrial iron overload and subsequent ROS production. We observed that frataxin expression was elevated in mice hearts subjected to I/R injury, and this response was blunted in cardiomyocyte-specific HIF-1α knockout (KO) mice. Furthermore, these HIF-1α KO mice sustained extensive cardiac damage from I/R injury compared with control mice. Similarly, reduction of HIF-1α by RNA inhibition resulted in an attenuation of frataxin expression in response to hypoxia in H9C2 cardiomyocytes. Therefore, we postulated that HIF-1α transcriptionally regulates frataxin expression in response to hypoxia and offers a cardioprotective mechanism against ischemic injury. Our promoter activity and chromatin immunoprecipitation assays confirmed the presence of a functional hypoxia response element in the frataxin promoter. Our data also suggest that increased frataxin mitigated mitochondrial iron overload and subsequent ROS production, thus preserving mitochondrial membrane integrity and viability of cardiomyocytes. We postulate that frataxin may exert its beneficial effects by acting as an iron storage protein under hypoxia and subsequently facilitates the maintenance of mitochondrial membrane potential and promotes cell survival. The findings from our study revealed that HIF-1α-frataxin signaling promotes a protective mechanism against hypoxic/ischemic stress.

We examined the effects of interleukin-1β (IL-1β) treatment on the distribution and degradation of lamin B in the nuclear fraction from insulin-secreting RINm5F cells. Western blot analysis indicated that IL-1β treatment caused significant alterations in the redistribution of lamin B, specifically between the Triton X-100-soluble (membrane) and -insoluble (matrix) fractions of the nucleus. IL-1β treatment also increased the lamin carboxymethyltransferase activity and the relative abundance of the carboxymethylated lamin in the nuclear fraction. A significant increase in the relative abundance of lamin B degradation products was also observed in the nuclear fraction from the IL-1β-treated cells. These findings are compatible with a measurable increase in the lamin-degrading caspase-6 activity in IL-1β-treated cells. Confocal microscopic observation of IL-1β-treated cells suggested a significant dissociation of lamin B from the nuclear lamina and its subsequent association with the DNA-rich elements within the nucleus. NG-monomethyl-l-arginine, a known inhibitor of inducible nitric oxide synthetase (iNOS), markedly inhibited IL-1β-induced iNOS gene expression, NO release, caspase-3 and caspase-6 activation, lamin B degradation, and loss of metabolic cell viability, indicating that the observed IL-1β-induced effects on nuclear lamin B involve the intermediacy of NO. Together, our data support the hypothesis that IL-1β treatment results in significant increase in the carboxymethylation of lamin B, which would place lamin B in a strategic location for its degradation mediated by caspases. This could possibly lead to dissolution of the nuclear envelope, culminating in the demise of the effete β-cell.

What is the central question of this study? Does the δ-opioid receptor trigger exercise-induced cardioprotection against ischaemia-reperfusion injury? What is the main finding and its importance? In exercised hearts, the δ-opioid receptor appears to trigger cardioprotection against ischaemia-reperfusion-induced tissue necrosis but not apoptosis.Endogenous opioids mediate exercise-induced cardioprotection against ischaemia-reperfusion (IR) injury, although the opioid receptor subtype mediating this effect is unknown. We investigated whether the δ-opioid receptor mediates exercise-induced cardioprotection against IR injury. Endogenous opioids are produced in various tissues, including the heart and skeletal muscle; therefore, we also sought to identify the effect of exercise on circulating endogenous opioid as well as transcript, protein and receptor expression in heart and skeletal muscle. Male Sprague-Dawley rats (n = 73) were assigned randomly to treadmill exercise or sedentary treatments. Cardiac tissue and serum were harvested 0, 20 and 120 min following exercise and from sedentary animals (n = 32) to quantify effects on proenkephalin and δ-opioid receptor mRNA and protein levels, as well as serum enkephalin. Skeletal muscle (soleus) was harvested at identical time points for determination of proenkephalin protein and mRNA. A separate group of rats (n = 41) were randomly assigned to sham operation (Sham; surgical control), sedentary (Sed), exercise (Ex) or exercise + δ-opioid receptor antagonist (ExD; naltrindole, 5 mg kg(-1) i.p.) and received IR by left anterior descending coronary artery ligation in vivo. After IR, tissues were harvested to quantify treatment effects on necrosis and apoptosis. Cardiac proenkephalin mRNA expression increased following exercise (0 min, P = 0.03; 120 min, P = 0.021), while soleus expression was unaffected. Exercise-induced changes in serum enkephalin were undetectable. After IR, tissue necrosis was elevated in Sed and ExD hearts (P 0.001 and P = 0.003, respectively) compared with the Sham group, while the Ex group was partly protected. After IR, apoptosis was evident in Sed hearts (P = 0.016), while Ex and ExD hearts were protected. Data suggest that cardioprotective opioids are produced by the heart, but not by the soleus. After IR, the δ-opioid receptor may mediate, in part, cardioprotection against necrosis but not apoptosis.

What is the central question of this study? Does dietary quercetin enrichment improve biochemical and histological outcomes in hearts from mdx mice? What is the main finding and what is its importance? Biochemical and histological findings suggest that chronic quercetin feeding of mdx mice may improve mitochondrial function and attenuate tissue pathology. Patients with Duchenne muscular dystrophy suffer from cardiac pathology, which causes up to 40% of all deaths because of fibrosis and cardiac complications. Quercetin is a flavonol with anti-inflammatory and antioxidant effects and is also an activator of peroxisome proliferator-activated receptor γ coactivator 1α capable of antioxidant upregulation, mitochondrial biogenesis and prevention of cardiac complications. We sought to determine the extent to which dietary quercetin enrichment prevents (experiment 1) and rescues cardiac pathology (experiment 2) in mdx mice. In experiment 1, 3-week-old mdx mice were fed control chow (C3w6m, n = 10) or chow containing 0.2% quercetin for 6 months (Q3w6m, n = 10). In experiment 2, 3-month-old mdx mice were fed control chow (C3m6m, n = 10) or 0.2% chow containing 0.2% quercetin for 6 months (Q3m6m, n = 10). Hearts were excised for histological and biochemical analyses. In experiment 1, Western blot targets for mitochondrial biogenesis (cytochrome c, P = 0.007) and antioxidant expression (superoxide dismutase 2, P = 0.014) increased in Q3w6m mice compared with C3w6m. Histology revealed increased utrophin (P = 0.025) and decreased matrix metalloproteinase 9 abundance (P = 0.040) in Q3w6m mice compared with C3w6m. In experiment 2, relative (P = 0.023) and absolute heart weights (P = 0.020) decreased in Q3m6m mice compared with C3m6m. Indications of damage (Haematoxylin- and Eosin-stained sections, P = 0.007) and Western blot analysis of transforming growth factor β1 (P = 0.009) were decreased in Q3m6m mice. Six months of quercetin feeding increased a mitochondrial biomarker, antioxidant protein and utrophin and decreased matrix metalloproteinase 9 in young mice. Given that these adaptations are associated with attenuated cardiac pathology and damage, the present findings may indicate that dietary quercetin enrichment attenuates dystrophic cardiac pathology, but physiological confirmation is needed.

Cardiotoxicity associated with the use of doxorubicin (DOX), and other chemotherapeutics, limits their clinical potential. This study determined the pharmacokinetics and antitumor and cardioprotective activity of free and liposome encapsulated phenyl-2-aminoethyl-selenide (PAESe).The pharmacokinetics of free PAESe and PAESe encapsulated in liposomes (SSL-PAESe) were determined in rats using liquid chromatography tandem mass-spectrometry. The antitumor and cardioprotective effects were determined in a mouse xenograft model of human prostate (PC-3) cancer and cardiomyocytes (H9C2).The encapsulation of PAESe in liposomes increased the circulation half-life and area under the drug concentration time profile, and decreased total systemic clearance significantly compared to free PAESe. Free- and SSL-PAESe improved survival, decreased weight-loss and prevented cardiac hypertrophy significantly in tumor bearing and healthy mice following treatment with DOX at 5 and 12.5 mg/kg. In vitro studies revealed PAESe treatment altered formation of reactive oxygen species (ROS), cardiac hypertrophy and gene expression, i.e., atrial natriuretic peptide and myosin heavy chain complex beta, in H9C2 cells.Treatment with free and SSL-PAESe exhibited antitumor activity in a prostate xenograft model and mitigated DOX-mediated cardiotoxicity.

Background The purpose of this study was to examine if L-leucine (Leu), β-hydroxy-β-methylbutyrate (HMB), or creatine monohydrate (Crea) prevented potential atrophic effects of myostatin (MSTN) on differentiated C2C12 myotubes. Methods After four days of differentiation, myotubes were treated with MSTN (10 ng/ml) for two additional days and four treatment groups were studied: 1) 3x per day 10 mM Leu, 2) 3x per day 10 mM HMB, 3) 3x per day 10 mM Crea, 4) DM only. Myotubes treated with DM without MSTN were analyzed as the control condition (DM/CTL). Following treatment, cells were analyzed for total protein, DNA content, RNA content, muscle protein synthesis (MPS, SUnSET method), and fiber diameter. Separate batch treatments were analyzed for mRNA expression patterns of myostatin-related genes (Akirin-1/Mighty, Notch-1, Ski, MyoD) as well as atrogenes (MuRF-1, and MAFbx/Atrogin-1). Results MSTN decreased fiber diameter approximately 30% compared to DM/CTL myotubes (p

Diabetes and Alzheimer's disease share pathologic links toward cognitive deficits. Pharmacologic agonist of the nuclear receptor, peroxisomal proliferator-activating receptor gamma (PPARγ), that is, rosiglitazone (rosi), are insulin sensitizing agents that improve memory in Alzheimer's disease. However, direct molecular signaling targets that improve memory by PPARγ in the hippocampus have not been investigated. We compared outcomes from oral versus intracerebroventricular (ICV) administration of rosi on memory and changes in synaptic plasticity in type 2 diabetic (db/db) mice. Db/db mice treated with rosi (ICV) showed significant improvement in memory, long-term potentiation, and post-tetanic potentiation but did not improve peripheral insulin sensitivity. Gene and protein analysis revealed increased brain-derived neurotrophic factor (BDNF) in db/db mice treated with rosi (ICV). Transcriptional activation of exon IX as determined by luciferase assays confirmed PPARγ regulation of BDNF promoter activity. Transient transfection of constitutively active PPARγ plasmid in hippocampal neuronal cells induced increased BDNF, AMPA, and NMDA receptors expression and spine formation. Findings from the present study implicate a novel PPARγ-BDNF molecular signaling mechanism as a potential therapeutic target for cognitive impairment.

Insulin is secreted from the β-cells of the pancreas and helps maintain glucose homeostasis. Although secreted peripherally, insulin also plays a profound role in cognitive function. Increasing evidence suggests that insulin signaling in the brain is necessary to maintain health of neuronal cells, promote learning and memory, decrease oxidative stress, and ultimately increase neuronal survival. This chapter summarizes the different facets of insulin signaling necessary for learning and memory and additionally explores the association between cognitive impairment and central insulin resistance. The role of impaired insulin signaling in the advancement of cognitive dysfunction is relevant to the current debate of whether the shared pathophysiological mechanisms between diabetes and cognitive impairment implicate a direct relationship. Here, we summarize a vast amount of literature that suggests a strong association between impaired brain insulin signaling and cognitive impairment.

In the present study, we have shown that exposure of insulin-secreting clonal beta (HIT-T15) cells to interleukin-1beta (IL-1beta) results in a time- and concentration-dependent increase in nitric oxide (NO) release. These effects by IL-1beta on NO release were mediated by induction of inducible nitric oxide synthase (iNOS) from the cells. Preincubation of HIT cells with Clostridium sordellii lethal toxin-82, which irreversibly glucosylates and inactivates small G-proteins, such as Ras, Rap, Ral, and Rac, but not Cdc42, completely abolished IL-1beta-induced NO release. Pre-exposure of HIT cells to C. sordellii lethal toxin-9048, which monoglucosylates and inhibits Ras, Cdc42, Rac, and Rap, but not Ral, also attenuated IL-1beta-mediated NO release. These data indicate that activation of Ras and/or Rac may be necessary for IL-1beta-mediated NO release. Preincubation of HIT cells with C. difficile toxin-B, which monoglucosylates Rac, Cdc42, and Rho, had no demonstrable effects on IL-mediated NO release, ruling out the possibility that Rac may be involved in this signaling step. Further, two structurally dissimilar inhibitors of Ras function, namely manumycin A and damnacanthal, inhibited, in a concentration-dependent manner, the IL-1beta-mediated NO release from these cells. Together, our data provide evidence, for the first time, that Ras activation is an obligatory step in IL-1beta-mediated NO release and, presumably, the subsequent dysfunction of the pancreatic beta cell. Our data also provide a basis for future investigations to understand the mechanism of cytokine-induced beta cell death leading to the onset of insulin-dependent diabetes mellitus.

Insulin is secreted from the β-cells of the pancreas and helps maintain glucose homeostasis. Although secreted peripherally, insulin also plays a profound role in cognitive function. Increasing evidence suggests that insulin signaling in the brain is necessary to maintain health of neuronal cells, promote learning and memory, decrease oxidative stress, and ultimately increase neuronal survival. This chapter summarizes the different facets of insulin signaling necessary for learning and memory and additionally explores the association between cognitive impairment and central insulin resistance. The role of impaired insulin signaling in the advancement of cognitive dysfunction is relevant to the current debate of whether the shared pathophysiological mechanisms between diabetes and cognitive impairment implicate a direct relationship. Here, we summarize a vast amount of literature that suggests a strong association between impaired brain insulin signaling and cognitive impairment.

PURPOSE: To test the hypothesis that neovascular age-related macular degeneration is related to oxidative stress involving the macular retinal pigment epithelium. This study investigated, as a function of age, levels of enzymes that defend tissues against oxidative stress in the macular retinal pigment epithelium of human eyes with this disease. METHODS: Surgical specimens of macular choroidal neovascular membranes from eyes with age-related macular degeneration and the macular regions of whole donor eyes with neovascular age-related macular degeneration or without evident ocular disease were studied by quantitative electron microscopic immunocytochemistry with colloidal gold–labeled second antibodies. Relative levels in retinal pigment epithelium cell cytoplasm and lysosomes were determined of five enzymes believed to protect cells from oxidative stress, as well as levels of the retinal pigment epithelium marker cytoplasmic retinaldehyde-binding protein, for comparison with the enzymes. RESULTS: Copper, zinc superoxide dismutase immunoreactivity increased and catalase immunoreactivity decreased with age in cytoplasm and lysosomes from macular retinal pigment epithelium cells of normal eyes and eyes with age-related macular degeneration. Cytoplasmic retinaldehyde-binding protein immunoreactivity showed no significant relationship to age or the presence of neovascular age-related macular degeneration. Glutathione peroxidase immunoreactivity was absent from human retinal pigment epithelium cells. Both heme oxygenase-1 and heme oxygenase-2 had highly significantly greater immunoreactivity in retinal pigment epithelium cell lysosomes than in cytoplasm, differing from the much greater cytoplasmic immunoreactivity of the other proteins studied. This immunoreactivity decreased with age, particularly in the lysosomes of retinal pigment epithelium cells from eyes with neovascular age-related macular degeneration. These decreases were of borderline significance ( P = .067 for heme oxygenase-1; P = .12 for heme oxygenase-2) when eyes with age-related macular degeneration were compared with normal eyes by multivariable logistic regression. CONCLUSIONS: The high heme oxygenase-1 and heme oxygenase-2 lysosomal antigen levels in macular retinal pigment epithelium cells of eyes with neovascular age-related macular degeneration suggest that oxidative stress causes a pathologic upregulation of these enzymes. Increased lysosomal disposal may indicate that the reparative functions of these enzymes are accompanied by deleterious effects, necessitating their rapid removal from the cell. The much higher heme oxygenase-1 and heme oxygenase-2 antigen levels in macular retinal pigment epithelium cells from younger individuals suggest that protective mechanisms against oxidation and, hence, presumably to the development of age-related macular degeneration, decrease with age.

Interaction between the γ subunit (Pγ) of cGMP phosphodiesterase and the α subunit (Tα) of transducin is a key step for the regulation of cGMP phosphodiesterase in retinal rod outer segments. Here we have utilized a combination of specific modification by an endogenous enzyme and site-directed mutagenesis of the Pγ polycationic region to identify residues required for the interaction with Tα. Pγ, free or complexed with the αβ subunit (Pαβ) of cGMP phosphodiesterase, was specifically radiolabeled by prewashed rod membranes in the presence of [adenylate-32P]NAD. Identification of ADP-ribose in the radiolabeled Pγ and radiolabeling of arginine-replaced mutant forms of Pγ indicate that both arginine 33 and arginine 36 are similarly ADP-ribosylated by endogenous ADP-ribosyltransferase, but only one arginine is modified at a time. Pγ complexed with Tα (both GTP- and GDP-bound forms) was not ADP-ribosylated; however, agmatine, which cannot interact with Tα, was ADP-ribosylated in the presence of Tα, suggesting that a Pγ domain containing these arginines is masked by Tα. A Pγ mutant (R33,36K), as well as wild type Pγ, inhibited both GTP hydrolysis of Tα and GTP binding to Tα. Moreover, GTP-bound Tα activated Pαβ that had been inhibited by R33,36K. However, another Pγ mutant (R33,36L) could not inhibit these Tα functions. In addition, GTP-bound Tα could not activate Pαβ inhibited by R33,36L. These results indicate that a Pγ domain containing these arginines is required for its interaction with Tα, but not with Pαβ, and that positive charges in these arginines are crucial for the interaction.

Purpose To determine whether vascular endothelial growth factor and basic fibroblast growth factor, which may be critical mitogens for neovascularization, are present together in human retinal and choroidal neovascular membranes. Methods Light microscopic immunocytochemistry using antibodies against vascular endothelial growth factor, basic fibroblast growth factor, and several cellular “oemarker” proteins on frozen sections from three choroidal neovascular membranes from patients with age-related macular degeneration, seven surgically excised epiretinal membranes from patients with proliferative diabetic retinopathy, and six epiretinal membranes from patients with nonischemic proliferative retinopathies. Results All three choroidal neovascular membranes and all seven epiretinal membranes stained positive for vascular endothelial growth factor. Two choroidal neovascular membranes and six of the epiretinal membranes were positive for basic fibroblast growth factor. The same cells were often positive for both antigens. None of the epiretinal membranes from patients with nonischemic proliferative retinopathies were positive for either growth factor. Many of the cells that demonstrated growth factors were glial cells, vascular endothelial cells, and retinal pigment epithelial cells. Conclusions Colocalization of two growth factors in the same cells of ocular neovascular membranes suggests that more than one growth factor may contribute to pathologic angiogenesis. Growth factors in neovascular tissues are not localized exclusively in the vascular endothelium. Because expression of some growth factors is stimulated by hypoxia, their localization within choroidal neovascular membranes suggests that hypoxia may be an etiologic factor for choroidal as well as for retinal neovascularization.

Adiponectin is an endogenous insulin-sensitizing hormone which has been found to regulate energy metabolism throughout the body, including the heart. However, low levels of adiponectin are found in patients with diabetes, hypertension and cardiovascular diseases. Thus it has been suggested to be an independent predictor for cardiovascular risk. Paradoxically, recent studies have also determined that adiponectin has cardioprotective effects against various cardiac related pathologies which lead to heart failure. These cardioprotective effects of adiponectin are attributed to its anti-inflammatory, anti-oxidant and anti-apoptotic properties. Further findings suggest that locally produced adiponectin in cardiomyocytes are functional and biologically significant. This ectopic derived adiponectin exerts its protective effects through an autocrine mechanism. These data suggest adiponectin may serve as a potential therapeutic target against the development of pathologies which develop into heart failure. The current manuscript has summarized the key findings to date which explore the cardioprotective mechanisms of adiponectin against various cardiac pathologies. Further we explore the roles of both circulating and endogenous heart specific adiponectin and their physiological importance in various heart diseases.

Patients with diabetes exhibit significantly altered renin-angiotensin system (RAS) control. Recently, it has been determined that hyperglycemic conditions induce an increase in angiotensin II (AT II) expression; specifically by cardiomyocytes. Altered RAS has been shown to be associated with an increase in oxidative stress and cardiac dysfunction leading to the development of cardiac hypertrophy. The transient outward potassium current (I(to)) in cardiac myocytes is mainly mediated by members of the Kv subfamily of voltage gated potassium channels and has been shown to be altered in cellular localization and expression during the development of cardiac hypertrophy. However it is not clear as to how AT II affects the pore forming complex at the cell membrane and thus directly affects the I(to) current. In the current study, we explored the protective effect of PPARγ ligands on cardiomyocyte I(to) by preventing NADPH Oxidase activation and the ensuing ROS formation. Furthermore, short term PPARγ activation in diabetic leptin deficient db/db mice displayed improvements in the membrane association of the molecular components of I(to) as well as prolonged QT interval. These findings demonstrate that PPARγ agonists have the potential to attenuate cardiomyocyte dysfunction associated with diabetes.

Diabetes associated heart disease is at epidemic proportions often manifesting as ischemic heart disease. Therapies which improve myocardial energy availability mitigate the development of myocardi...