An Unsuspected Metabolic Role for Atrial Natriuretic Peptides

The Role of Epicardial Adipose Tissue in Acute Coronary Syndromes, Post-Infarct Remodeling and Cardiac Regeneration

Epicardial adipose tissue (EAT) is a fat deposit surrounding the heart and located under the visceral layer of the pericardium. Due to its unique features, the contribution of EAT to the pathogenesis of cardiovascular and metabolic disorders is extensively studied. Especially, EAT can be associated with the onset and development of coronary artery disease, myocardial infarction and post-infarct heart failure which all are significant problems for public health. In this article, we focus on the mechanisms of how EAT impacts acute coronary syndromes. Particular emphasis was placed on the role of inflammation and adipokines secreted by EAT. Moreover, we present how EAT affects the remodeling of the heart following myocardial infarction. We further review the role of EAT as a source of stem cells for cardiac regeneration. In addition, we describe the imaging assessment of EAT, its prognostic value, and its correlation with the clinical characteristics of patients.

Atrial natriuretic peptide signaling co-regulates lipid metabolism and ventricular conduction system gene expression in the embryonic heart

It has been shown that atrial natriuretic peptide (ANP) and its high affinity receptor (NPRA) are involved in the formation of ventricular conduction system (VCS). Inherited genetic variants in fatty acid oxidation (FAO) genes are known to cause conduction abnormalities in newborn children. Although the effect of ANP on energy metabolism in noncardiac cell types is well documented, the role of lipid metabolism in VCS cell differentiation via ANP/NPRA signaling is not known. In this study, histological sections and primary cultures obtained from E11.5 mouse ventricles were analyzed to determine the role of metabolic adaptations in VCS cell fate determination and maturation. Exogenous treatment of E11.5 ventricular cells with ANP revealed a significant increase in lipid droplet accumulation, FAO and higher expression of VCS marker Cx40. Using specific inhibitors, we further identified PPARγ and FAO as critical downstream regulators of ANP-mediated regulation of metabolism and VCS formation.

MANP in Hypertension With Metabolic Syndrome: Proof-of-Concept Study of Natriuretic Peptide-Based Therapy for Cardiometabolic Disease

Hypertension and metabolic syndrome frequently coexist to increase the risk for adverse cardiometabolic outcomes. To date, no drug has been proven to be effective in treating hypertension with metabolic syndrome. M-atrial natriuretic peptide is a novel atrial natriuretic peptide analog that activates the particulate guanylyl cyclase A receptor. This study conducted a double-blind, placebo-controlled trial in 22 patients and demonstrated that a single subcutaneous injection of M-atrial natriuretic peptide was safe, well-tolerated, and exerted pleiotropic properties including blood pressure-lowering, lipolytic, and insulin resistance-improving effects. (MANP in Hypertension and Metabolic Syndrome [MANP-HTN-MS]; NCT03781739).

Role of Cardiac Natriuretic Peptides in Heart Structure and Function

Cardiac natriuretic peptides (NPs), atrial NP (ANP) and B-type NP (BNP) are true hormones produced and released by cardiomyocytes, exerting several systemic effects. Together with C-type NP (CNP), mainly expressed by endothelial cells, they also exert several paracrine and autocrine activities on the heart itself, contributing to cardiovascular (CV) health. In addition to their natriuretic, vasorelaxant, metabolic and antiproliferative systemic properties, NPs prevent cardiac hypertrophy, fibrosis, arrhythmias and cardiomyopathies, counteracting the development and progression of heart failure (HF). Moreover, recent studies revealed that a protein structurally similar to NPs mainly produced by skeletal muscles and osteoblasts called musclin/osteocrin is able to interact with the NPs clearance receptor, attenuating cardiac dysfunction and myocardial fibrosis and promoting heart protection during pathological overload. This narrative review is focused on the direct activities of this molecule family on the heart, reporting both experimental and human studies that are clinically relevant for physicians.

Ketogenic diets and Ketone suplementation: A strategy for therapeutic intervention

Ketogenic diets and orally administered exogenous ketone supplements are strategies to increase serum ketone bodies serving as an alternative energy fuel for high energy demanding tissues, such as the brain, muscles, and the heart. The ketogenic diet is a low-carbohydrate and fat-rich diet, whereas ketone supplements are usually supplied as esters or salts. Nutritional ketosis, defined as serum ketone concentrations of ≥ 0.5 mmol/L, has a fasting-like effect and results in all sorts of metabolic shifts and thereby enhancing the health status. In this review, we thus discuss the different interventions to reach nutritional ketosis, and summarize the effects on heart diseases, epilepsy, mitochondrial diseases, and neurodegenerative disorders. Interest in the proposed therapeutic benefits of nutritional ketosis has been growing the past recent years. The implication of this nutritional intervention is becoming more evident and has shown interesting potential. Mechanistic insights explaining the overall health effects of the ketogenic state, will lead to precision nutrition for the latter diseases.

The effect of adenosine monophosphate-activated protein kinase on lipolysis in adipose tissue: an historical and comprehensive review

CONTEXT

Lipolysis is one of the most important pathways for energy management, its control in the adipose tissue (AT) is a potential therapeutic target for metabolic diseases. Adenosine Mono Phosphate-activated Protein Kinase (AMPK) is a key regulatory enzyme in lipids metabolism and a potential target for diabetes and obesity treatment.

OBJECTIVE

The aim of this work is to analyse the existing information on the relationship of AMPK and lipolysis in the AT.

METHODS

A thorough search of bibliography was performed in the databases Scopus and Web of Knowledge using the terms lipolysis, adipose tissue, and AMPK, the unrelated publications were excluded, and the documents were analysed.

RESULTS

Sixty-three works were found and classified in 3 categories: inhibitory effects, stimulatory effect, and diverse relationships; remarkably, the newest researches support an upregulating relationship of AMPK over lipolysis.

CONCLUSION

The most probable reality is that the relationship AMPK-lipolysis depends on the experimental conditions.

Role of Distinct Fat Depots in Metabolic Regulation and Pathological Implications

People suffering from obesity and associated metabolic disorders including diabetes are increasing exponentially around the world. Adipose tissue (AT) distribution and alteration in their biochemical properties play a major role in the pathogenesis of these diseases. Emerging evidence suggests that AT heterogeneity and depot-specific physiological changes are vital in the development of insulin resistance in peripheral tissues like muscle and liver. Classically, AT depots are classified into white adipose tissue (WAT) and brown adipose tissue (BAT); WAT is the site of fatty acid storage, while BAT is a dedicated organ of metabolic heat production. The discovery of beige adipocyte clusters in WAT depots indicates AT heterogeneity has a more central role than hither to ascribed. Therefore, we have discussed in detail the current state of understanding on cellular and molecular origin of different AT depots and their relevance toward physiological metabolic homeostasis. A major focus is to highlight the correlation between altered WAT distribution in the body and metabolic pathogenesis in animal models and humans. We have also underscored the disparity in the molecular (including signaling) changes in various WAT tissues during diabetic pathogenesis. Exercise-mediated beneficial alteration in WAT physiology/distribution that protects against metabolic disorders is evolving. Here we have discussed the depot-specific biochemical adjustments induced by different forms of exercise. A detailed understanding of the molecular details of inter-organ crosstalk via substrate utilization/storage and signaling through chemokines provide strategies to target selected WAT depots to pharmacologically mimic the benefits of exercise countering metabolic diseases including diabetes.

Redox Regulation of Lipid Mobilization in Adipose Tissues

Lipid mobilization in adipose tissues, which includes lipogenesis and lipolysis, is a paramount process in regulating systemic energy metabolism. Reactive oxygen and nitrogen species (ROS and RNS) are byproducts of cellular metabolism that exert signaling functions in several cellular processes, including lipolysis and lipogenesis. During lipolysis, the adipose tissue generates ROS and RNS and thus requires a robust antioxidant response to maintain tight regulation of redox signaling. This review will discuss the production of ROS and RNS within the adipose tissue, their role in regulating lipolysis and lipogenesis, and the implications of antioxidants on lipid mobilization.

Influence of Aging and Menstrual Status on Subcutaneous Fat Cell Lipolysis

CONTEXT

Aging is accompanied by inhibited fat cell mobilization of fatty acids through lipolysis, which may contribute to decreased energy expenditure in elderly subjects. However, the influence of menstrual status is unknown.

OBJECTIVE

To investigate the role of menstrual status on changes in lipolysis induced by aging.

DESIGN

A longitudinal investigation with a mean 13-year interval.

SETTING

Ambulatory study at a clinical academic unit.

PARTICIPANTS

Eighty-two continuously recruited women between 24 and 62 years of age and with body mass index 21 to 48 kg/m2 at first examination. Twenty-nine women continued to have normal menstruation, 42 developed irregular menstruation/menopause, and 11 had a perimenstrual/menopausal phenotype already at the first examination.

MAIN OUTCOME MEASURE

Lipolysis measured as glycerol release from isolated subcutaneous fat cells incubated in vitro.

RESULTS

On average, body weight/body fat mass levels did not change over time. In all 3 groups, aging was associated with a similar decrease in spontaneous (basal) and catecholamine-stimulated lipolysis. The latter was due to decreased signal transduction through stimulatory beta adrenoceptors and increased alpha-2-adrenoceptor-mediated antilipolytic effects. Gene microarray data from adipose tissue at baseline and follow-up (n = 53) showed that a limited set of lipolysis-linked genes, including phosphodiesterase-3B, were altered over time, but this was independent of menstrual status. Fat cell size also decreased during aging, but this could not explain the decrease in lipolysis.

CONCLUSIONS

In women, the rate of fat cell lipolysis decreases during aging due to multiple alterations in spontaneous (basal) and catecholamine-induced lipolysis. This is independent of changes in menstrual status or fat cell size.

Interventions in the B-type natriuretic peptide signalling pathway as a means of controlling chronic itch

Chronic itch poses major health care and economic burdens worldwide. In 2013, B-type natriuretic peptide (BNP) was identified as an itch-selective neuropeptide and shown to be both necessary and sufficient to produce itch behaviour in mice. Since then, mechanistic studies of itch have increased, not only at central levels of the spinal relay of itch signalling but also in the periphery and skin. In this review, we have critically analysed recent findings from complementary pharmacological and physiological approaches, combined with genetic strategies to examine the role of BNP in itch transduction and modulation of other pruritic proteins. Additionally, potential targets and possible strategies against BNP signalling are discussed for developing novel therapeutics in itch. Overall, we aim to provide insights into drug development by altering BNP signalling to modulate disease symptoms in chronic itch, including conditions for which no approved treatment exists.

Plasma proatrial natriuretic peptide associates with lipid oxidation during exercise and cardiorespiratory fitness in healthy young adults

Atrial natriuretic peptide (ANP) is known for its natriuretic, diuretic, and vasodilatory properties. However, ANP also has metabolic effects stimulating lipolysis and lipid oxidation. Overweight individuals have decreased circulating ANP concentrations. It has been proposed that this potential ANP deficiency could have biological consequences in overweight-related disorders, including decreased lipolysis and lipid oxidation. The purpose of this study was to investigate the relationships between ANP, exercise-induced lipid oxidation, and cardiorespiratory fitness in 562 20-28-year-old healthy community-based women and men. We measured fasting plasma concentrations of mid-regional proANP (MR-proANP), a stable marker of ANP secretion, the respiratory exchange ratio (RER) during sub-maximal exercise, which provides an estimate of lipid oxidation, and maximal oxygen consumption (VO₂-max) at the end of a maximal exercise test, which is a measure of cardiorespiratory fitness. An increase of 10 pmol/L in fasting plasma MR-proANP concentrations was related to an increase in relative VO₂-max of 0.78 (95% CI 0.36-1.09) ml O₂/min/kg and a decrease in RER of -0.0094 (-0.014 to -0.0045) in age- and sex-adjusted analysis (P < 0.001). Further adjusted for body mass index, a rise of 10 pmol/L in fasting plasma MR-proANP concentrations was associated with a rise in relative VO₂-max of 0.60 (0.28-0.92) ml O₂/min/kg and a fall in RER of -0.0096 (-0.015 to -0.0048) (P < 0.001). Fasting plasma MR-proANP concentrations associate with lipid oxidation during exercise and cardiorespiratory fitness in healthy young adults. The data support the existence of important connections between the endocrine heart, hemodynamics, and metabolism.

Circulatory factors associated with function and prognosis in patients with severe heart failure

Background

Multiple circulatory factors are increased in heart failure (HF). Many have been linked to cardiac and/or skeletal muscle tissue processes, which in turn might influence physical activity and/or capacity during HF. This study aimed to provide a better understanding of the mechanisms linking HF with the loss of peripheral function.

Methods and results

Physical capacity measured by maximum oxygen uptake, myocardial function (measured by echocardiography), physical activity (measured by accelerometry), and mortality data was collected for patients with severe symptomatic heart failure an ejection fraction < 35% (n = 66) and controls (n = 28). Plasma circulatory factors were quantified using a multiplex immunoassay. Multivariate (orthogonal projections to latent structures discriminant analysis) and univariate analyses identified many factors that differed significantly between HF and control subjects, mainly involving biological functions related to cell growth and cell adhesion, extracellular matrix organization, angiogenesis, and inflammation. Then, using principal component analysis, links between circulatory factors and physical capacity, daily physical activity, and myocardial function were identified. A subset of ten biomarkers differentially expressed in patients with HF vs controls covaried with physical capacity, daily physical activity, and myocardial function; eight of these also carried prognostic value. These included established plasma biomarkers of HF, such as NT-proBNP and ST2 along with recently identified factors such as GDF15, IGFBP7, and TfR, as well as a new factor, galectin-4.

Conclusions

These findings reinforce the importance of systemic circulatory factors linked to hemodynamic stress responses and inflammation in the pathogenesis and progress of HF disease. They also support established biomarkers for HF and suggest new plausible markers.

Graphic abstract

Electronic supplementary material

The online version of this article (10.1007/s00392-019-01554-3) contains supplementary material, which is available to authorized users.

Development and Validation of Risk Prediction Models for Cardiovascular Events in Black Adults: The Jackson Heart Study Cohort

IMPORTANCE

Cardiovascular risk assessment is a fundamental component of prevention of cardiovascular disease (CVD). However, commonly used prediction models have been formulated in primarily or exclusively white populations. Whether risk assessment in black adults is dissimilar to that in white adults is uncertain.

OBJECTIVES

To develop and validate risk prediction models for CVD incidence in black adults, incorporating standard risk factors, biomarkers, and subclinical disease.

DESIGN, SETTING, AND PARTICIPANTS

The Jackson Heart Study (JHS), a longitudinal community-based study of 5301 black adults in Jackson, Mississippi. Inclusive study dates were the date of a participant's first visit (September 2000 to March 2004) to December 31, 2011. The median (75th percentile) follow-up was 9.1 (9.7) years. The dates of the analysis were August 2013 to May 2015. Measurements included standard risk factors, including age, sex, body mass index, systolic and diastolic blood pressure, ratio of fasting total cholesterol to high-density lipoprotein cholesterol, estimated glomerular filtration rate, antihypertensive therapy, diabetes mellitus, and smoking; blood biomarkers; and subclinical disease measures, including ankle-brachial index, carotid intimal-medial thickness, and echocardiographic left ventricular hypertrophy and systolic dysfunction.

MAIN OUTCOMES AND MEASURES

Incident CVD event was defined as the first occurrence of myocardial infarction, coronary heart disease death, congestive heart failure, stroke, incident angina, or intermittent claudication. Model performance was compared with the American College of Cardiology/American Heart Association (ACC/AHA) CVD risk algorithm and the Framingham Risk Score (FHS) refitted to the JHS data and evaluated in the Atherosclerosis Risk in Communities (ARIC) and Multi-Ethnic Study of Atherosclerosis cohorts.

RESULTS

The study cohort comprised 3689 participants with mean (SD) age at baseline was 53 (11) years, and 64.8% (n = 2390) were female. Over a median of 9.1 years, 270 participants (166 women) experienced a first CVD event. A simple combination of standard CVD risk factors, B-type natriuretic peptide, and ankle-brachial index (model 6) yielded modest improvement over a model without B-type natriuretic peptide and ankle-brachial index (C statistic, 0.79; 95% CI, 0.75-0.83 [relative integrated discrimination improvement, 0.22; 95% CI, 0.15-0.30]). However, the reclassification improvement was not substantially different between model 6 and the ACC/AHA CVD Pooled Cohort risk equations or between model 6 and the FHS. The models discriminated reasonably well in the ARIC and Multi-Ethnic Study of Atherosclerosis data (C statistic range, 0.70-0.77).

CONCLUSIONS AND RELEVANCE

Our findings using the JHS data in the present study are valuable because they confirm that current FHS and ACC/AHA risk algorithms work well in black individuals and are not easily improved on. A unique risk calculator for black adults may not be necessary.

Association of fat mass profile with natriuretic peptide receptor alpha in subcutaneous adipose tissue of medication-free healthy men: A cross-sectional study

Background: Atrial natriuretic peptide increases lipolysis in human adipocytes by binding to natriuretic peptide receptor-A (NPRA). The aim of the current study was to examine the associations of NPRA mRNA of subcutaneous adipose tissue with fat mass, fat-free mass, body mass index (BMI) and arterial blood pressure in medication-free healthy men. Method: Thirty-two volunteers [age (years): 36.06±7.36, BMI: 27.60±4.63 (kg/m 2)] underwent assessments of body height/weight, % fat mass, fat-free mass (kg), blood pressure, and a subcutaneous adipose tissue biopsy via a surgical technique. Results: We found that NPRA mRNA was negatively associated with % fat mass (r=-0.40, R 2=0.16, p=0.03) and BMI (r=-0.45, R 2=0.20, p=0.01). Cohen's f 2 effect size analyses showed a small effect size between NPRA mRNA and BMI ( f 2 =0.25). One-way analysis of variance with Bonferroni post-hoc tests showed a tendency for mean differences of NPRA mRNA across BMI categories (p=0.06). This was confirmed by Cohen's d effect size analyses revealing a large effect size of NPRA mRNA between obese individuals (BMI≥30 kg/m 2) and either normal weight (BMI=19-25 kg/m 2; d=0.94) or overweight (BMI=25-30 kg/m 2; d=1.12) individuals. Conclusions: NPRA mRNA is negatively associated with % fat mass and BMI in medication-free healthy men, suggesting a possible role of NPRA in the control of fat mass accumulation.

Cardiac natriuretic peptides promote adipose 'browning' through mTOR complex-1

OBJECTIVE

Activation of thermogenesis in brown adipose tissue (BAT) and the ability to increase uncoupling protein 1 (UCP1) levels and mitochondrial biogenesis in white fat (termed 'browning'), has great therapeutic potential to treat obesity and its comorbidities because of the net increase in energy expenditure. β-adrenergic-cAMP-PKA signaling has long been known to regulate these processes. Recently PKA-dependent activation of mammalian target of rapamycin complex 1 (mTORC1) was shown to be necessary for adipose 'browning' as well as proper development of the interscapular BAT. In addition to cAMP-PKA signaling pathways, cGMP-PKG signaling also promotes this browning process; however, it is unclear whether or not mTORC1 is also necessary for cGMP-PKG induced browning.

METHOD

Activation of mTORC1 by natriuretic peptides (NP), which bind to and activate the membrane-bound guanylyl cyclase, NP receptor A (NPRA), was assessed in mouse and human adipocytes in vitro and mouse adipose tissue in vivo.

RESULTS

Activation of mTORC1 by NP-cGMP signaling was observed in both mouse and human adipocytes. We show that NP-NPRA-PKG signaling activate mTORC1 by direct PKG phosphorylation of Raptor at Serine 791. Administration of B-type natriuretic peptide (BNP) to mice induced Ucp1 expression in inguinal adipose tissue in vivo, which was completely blocked by the mTORC1 inhibitor rapamycin.

CONCLUSION

Our results demonstrate that NP-cGMP signaling activates mTORC1 via PKG, which is a component in the mechanism of adipose browning.

Adipocyte-specific expression of C-type natriuretic peptide suppresses lipid metabolism and adipocyte hypertrophy in adipose tissues in mice fed high-fat diet

C-type natriuretic peptide (CNP) is expressed in diverse tissues, including adipose and endothelium, and exerts its effects by binding to and activating its receptor, guanylyl cyclase B. Natriuretic peptides regulate intracellular cGMP and phosphorylated vasodilator-stimulated phosphoprotein (VASP). We recently revealed that overexpression of CNP in endothelial cells protects against high-fat diet (HFD)-induced obesity in mice. Given that endothelial CNP affects adipose tissue during obesity, CNP in adipocytes might directly regulate adipocyte function during obesity. Therefore, to elucidate the effect of CNP in adipocytes, we assessed 3T3-L1 adipocytes and transgenic (Tg) mice that overexpressed CNP specifically in adipocytes (A-CNP). We found that CNP activates the cGMP–VASP pathway in 3T3-L1 adipocytes. Compared with Wt mice, A-CNP Tg mice showed decreases in fat weight and adipocyte hypertrophy and increases in fatty acid β-oxidation, lipolysis-related gene expression, and energy expenditure during HFD-induced obesity. These effects led to decreased levels of the macrophage marker F4/80 in the mesenteric fat pad and reduced inflammation. Furthermore, A-CNP Tg mice showed improved glucose tolerance and insulin sensitivity, which were associated with enhanced insulin-stimulated Akt phosphorylation. Our results suggest that CNP overexpression in adipocytes protects against adipocyte hypertrophy, excess lipid metabolism, inflammation, and decreased insulin sensitivity during HFD-induced obesity.

A favorable cardiometabolic profile is associated with the G allele of the genetic variant rs5068 in African Americans: The Multi-Ethnic Study of Atherosclerosis (MESA)

In whites, the minor G allele of the atrial natriuretic peptide (ANP) genetic variant rs5068 is associated with higher circulating levels of ANP and B-type natriuretic peptide (BNP), lower risk of hypertension, higher high-density lipoprotein (HDL) cholesterol plasma levels, and lower prevalence of obesity and metabolic syndrome. The observed phenotype is consistent with the blood pressure lowering and metabolic properties of ANP and BNP. The cardiovascular and metabolic phenotype associated with rs5068 genotypes in African Americans is undefined. We genotyped 1631 African Americans in the Multi-Ethnic Study of Atherosclerosis (MESA) for rs5068 and investigated their phenotype. Genotype frequencies of rs5068 were 93.2% AA (n = 1520), 6.7% AG (n = 110) and 0.1% GG (n = 1). All subsequent analyses are AG + GG versus AA genotype. Using a Bonferroni corrected level of significance of 0.005, the prevalence of metabolic syndrome (23% vs 38%, age-sex-adjusted p = 0.002) and triglycerides plasma values (76 vs 90 mg/dl, age-sex-BMI adjusted p = 0.004) were both significantly lower in the AG+GG genotypes. In the AG+GG genotypes, the prevalence of diabetes (8% vs 18%, age-sex-BMI-adjusted p = 0.02) and insulin plasma levels tended to be lower (4.8 vs 5.7 μU/ml, age-sex-BMI adjusted p = 0.04) whereas HDL-cholesterol levels tended to be higher (55 vs 50 mg/dl, age-sex-BMI-adjusted p = 0.04). No association was found with hypertension. The association between the rs5068 G allele and a favorable metabolic phenotype is now shown in African Americans. The rs5068 AG+GG genotypes are associated with lower prevalence of metabolic syndrome and lower triglycerides values.

Brain Natriuretic Peptide Counteracting the Renin-angiotensin-aldosterone System in Accelerated Malignant Hypertension

We describe 2 patients, a 52-year-old woman and a 57-year-old man, with rapidly progressive hypertension and marked elevation of brain natriuretic peptide who exhibited polyuria, natriuresis, hypokalemia, posterior reversible encephalopathy syndrome and left ventricular dysfunction together with retinopathy and nephropathy, which were attenuated in a short time span of 1-2 months with normalization of blood pressure after the antihypertensive treatment. The possible role of brain natriuretic peptide in the pathophysiology of accelerated malignant hypertension was discussed and a review of the literature was completed.

Deep analyses of the associations of a series of biomarkers with insulin resistance, metabolic syndrome, and diabetes risk in nondiabetic middle-aged and elderly individuals: results from a Chinese community-based study

OBJECTIVE

The current study was designed to perform deep analyses of the associations of biomarkers, including high-sensitivity C-reactive protein (hs-CRP), N-terminal prohormone of brain natriuretic peptide (NT-proBNP), and homocysteine (Hcy), with insulin resistance (IR), metabolic syndrome (MetS), and diabetes risk and evaluate the abilities of biomarkers to identify IR, MetS, and diabetes risk in Chinese community-dwelling middle-aged and elderly residents.

PARTICIPANTS AND METHODS

A total of 396 participants older than 45 years underwent physical examinations and laboratory analyses following standardized protocol.

RESULTS

Serum hs-CRP concentrations were able to identify MetS, Chinese diabetes risk score (CDRS) ≥4, high-density lipoprotein-cholesterol (HDL-c) <0.9/1.0 mmol/L, and HDL-c <1.0/1.3 mmol/L (P<0.05 for all). Serum NT-proBNP concentrations were able to identify homeostasis model assessment of IR >1.5, CDRS ≥4, overweight, and blood pressure (BP) ≥140/90 mmHg (P<0.05 for all). Serum Hcy concentrations were able to identify CDRS ≥4, general obesity, overweight, and BP ≥140/90 mmHg (P<0.05 for all). Serum hs-CRP concentrations were independently associated with MetS as well as HDL-c <1.0/1.3 mmol/L and HDL-c <0.9/1.0 mmol/L (P<0.05 for all). Serum NT-proBNP concentrations were independently associated with BP ≥140/90 mmHg (P<0.05). Serum Hcy concentrations were independently associated with CDRS ≥4 (P<0.05).

CONCLUSION

Serum HDL-c levels were the major determinant of the associations between serum hs-CRP levels and MetS and the key link between inflammation and MetS. There was no other association of these biomarkers with IR, MetS, and diabetes risk after full adjustment.

The Physiological Regulation of Skeletal Muscle Fatty Acid Supply and Oxidation During Moderate-Intensity Exercise

Energy substrates that are important to the working muscle at moderate intensities are the non-esterified fatty acids (NEFAs) taken up from the circulation and NEFAs originating from lipolysis of the intramuscular triacylglycerol (IMTAG). Moreover, NEFA from lipolysis via lipoprotein lipase (LPL) in the muscle of the very-low-density lipoproteins and in the (semi) post-prandial state chylomicrons may also contribute. In this review, the NEFA fluxes and oxidation by skeletal muscle during prolonged moderate-intensity exercise are described in terms of the integration of physiological systems. Steps involved in the regulation of the active muscle NEFA uptake include (1) increased energy demand; (2) delivery of NEFA to the muscle; (3) transport of NEFA into the muscle by NEFA transporters; and (4) activation of the NEFAs and either oxidation or re-esterification into IMTAG. The increased metabolic demand of the exercising muscle is the main driving force for all physiological regulatory processes. It elicits functional hyperemia, increasing the recruitment of capillaries and muscle blood flow resulting in increased NEFA delivery and accessibility to NEFA transporters and LPL. It also releases epinephrine that augments adipose tissue NEFA release and thereby NEFA delivery to the active muscle. Moreover, NEFA transporters translocate to the plasma membrane, further increasing the NEFA uptake. The majority of the NEFAs taken up by the active muscle is oxidized and a minor portion is re-esterified to IMTAG. Net IMTAG lipolysis occurs; however, the IMTAG contribution to total fat oxidation is rather limited compared to plasma-derived NEFA oxidation, suggesting a complex role and regulation of IMTAG utilization.

Integrated analysis of serum and intact muscle metabonomics identify metabolic profiles of cancer cachexia in a dynamic mouse model

An integrated analysis of 13 metabolites from the intact muscle gastrocnemius and 43 metabolites from the serum reveals five distinguishable metabolic features of cancer cachexia.

Exercise per se masks oral contraceptive-induced postprandial lipid mobilization

Because of their hormonal content, oral contraceptives may alter lipolytic activity under resting or exercise conditions in women. The aim of the present study was to compare lipid mobilization in a postprandial state at rest and during exercise in oral contraceptive users (OC+) versus nonusers (OC–). The metabolic (glucose, glycerol, free fatty acids) and hormonal (insulin, atrial natriuretic peptide (ANP), growth hormone, insulin-like growth factor-1 (IGF-1), and catecholamines) concentrations were determined in 11 OC+ (monophasic low-dose oral contraceptives) and 10 OC– during a resting and an exercise session (45 min at 65% maximal oxygen consumption). Results were expressed as plasma concentrations and area under the concentration versus time curve values. ANP concentrations were higher in OC+ compared with OC– women at baseline (p = 0.04). Plasma concentrations of glycerol (p = 0.04), free fatty acids (p = 0.04), ANP (p = 0.02), and noradrenaline (p = 0.04) were higher in OC+ compared with OC– when both sessions were pooled. The plasma growth hormone, IGF-1, and adrenaline concentrations were not significantly different between the 2 groups. When the effect of exercise was isolated to overcome food intake and daytime variations (exercise per se using the area under the curve), no difference was observed between groups for all metabolic and hormonal variables. Overall, oral contraceptives increased lipid mobilization in the postprandial state, but this effect was blunted when lipolytic activity was stimulated by exercise per se. Oral contraceptive-induced greater lipolytic mobilization could be partly explained by greater ANP levels in OC users.

Obesity and natriuretic peptides, BNP and NT-proBNP: mechanisms and diagnostic implications for heart failure

Many advances have been made in the diagnosis and management of heart failure (HF) in recent years. Cardiac biomarkers are an essential tool for clinicians: point of care B-type natriuretic peptide (BNP) and its N-terminal counterpart (NT-proBNP) levels help distinguish cardiac from non-cardiac causes of dyspnea and are also useful in the prognosis and monitoring of the efficacy of therapy. One of the major limitations of HF biomarkers is in obese patients where the relationship between BNP and NT-proBNP levels and myocardial stiffness is complex. Recent data suggest an inverse relationship between BNP and NT-proBNP levels and body mass index. Given the ever-increasing prevalence of obesity world-wide, it is important to understand the benefits and limitations of HF biomarkers in this population. This review will explore the biology, physiology, and pathophysiology of these peptides and the cardiac endocrine paradox in HF. We also examine the clinical evidence, mechanisms, and plausible biological explanations for the discord between BNP levels and HF in obese patients.

Fat mass localization alters fuel oxidation during exercise in normal weight women

PURPOSE

Abdominal and lower body fat mass tissues exhibit particular metabolic profiles at rest and during exercise. However, data are missing in normal weight women during exercise. The purpose of this study was to investigate the effect of low (LA/LB) and high (HA/LB) abdominal to lower body (A/LB) fat mass ratio on metabolic and hormonal responses during exercise in premenopausal normal weight women.

METHODS

After preliminary testing (V˙O2max and body composition assessment), substrate oxidation (RER, lipid, and carbohydrate oxidation rates), metabolic response (glycerol, free fatty acids, and glucose), and hormonal response (insulin, growth hormone, atrial natriuretic peptide, adrenaline, and noradrenaline) were determined during exercise (45 min at 65% of V˙O2max) in 21 premenopausal normal weight women (10 HA/LB women vs 11 LA/LB women).

RESULTS

Waist circumference was significantly higher in HA/LB women compared with LA/LB women (P < 0.01). No difference in other anthropometric characteristics, V˙O2max, and resting blood values was observed between the two groups. LA/LB subjects exhibited greater lipid oxidation rates compared with HA/LB women during exercise (P < 0.01). This occurred with lower plasma insulin (P < 0.05) and glucose (P < 0.05) concentrations and higher plasma free fatty acids (P < 0.05), glycerol (P < 0.05), growth hormone (P < 0.05), and atrial natriuretic peptide levels (P < 0.01) during exercise in the LA/LB group compared with the HA/LB group.

CONCLUSIONS

The present study demonstrated that LA/LB women exhibited an increase in whole-body lipid mobilization and use during exercise compared with HA/LB counterparts. This greater reliance on lipid as fuel metabolism during exercise could be explained by substrate availability and metabolic and hormonal responses. It appeared that LA/LB women exhibited greater metabolic flexibility during an exercise bout of 45 min at 65% of V˙O2max on cycle ergometer.

A systematic review of fetal genes as biomarkers of cardiac hypertrophy in rodent models of diabetes

Pathological cardiac hypertrophy activates a suite of genes called the fetal gene program (FGP). Pathological hypertrophy occurs in diabetic cardiomyopathy (DCM); therefore, the FGP is widely used as a biomarker of DCM in animal studies. However, it is unknown whether the FGP is a consistent marker of hypertrophy in rodent models of diabetes. Therefore, we analyzed this relationship in 94 systematically selected studies. Results showed that diabetes induced with cytotoxic glucose analogs such as streptozotocin was associated with decreased cardiac weight, but genetic or diet-induced models of diabetes were significantly more likely to show cardiac hypertrophy (P<0.05). Animal strain, sex, age, and duration of diabetes did not moderate this effect. There were no correlations between the heart weight:body weight index and mRNA or protein levels of the fetal genes α-myosin heavy chain (α-MHC) or β-MHC, sarco/endoplasmic reticulum Ca²⁺-ATPase, atrial natriuretic peptide (ANP), or brain natriuretic peptide. The only correlates of non-indexed heart weight were the protein levels of α-MHC (Spearman's ρ = 1, P<0.05) and ANP (ρ = −0.73, P<0.05). These results indicate that most commonly measured genes in the FGP are confounded by diabetogenic methods, and are not associated with cardiac hypertrophy in rodent models of diabetes.

Influence of lipolysis and fatty acid availability on fuel selection during exercise

The aim of the present study was to investigate the influence of substrate availability on fuel selection during exercise. Eight endurance-trained male cyclists performed 90-min exercise at 70% of their maximal oxygen uptake in a cross-over design, either in rested condition (CON) or the day after 2-h exercise practised at 70% of maximal oxygen uptake (EX). Subjects were given a sucrose load (0.75 g kg(-1) body weight) 45 min after the beginning of the 90-min exercise test. Lipolysis was measured in subcutaneous abdominal adipose tissue (SCAT) by microdialysis and substrate oxidation by indirect calorimetry. Lipid oxidation increased during exercise and tended to decrease during sucrose ingestion in both conditions. Lipid oxidation was higher during the whole experimental period in the EX group (p = 0.004). Interestingly, fuel selection, assessed by the change in respiratory exchange ratio (RER), was increased in the EX session (p = 0.002). This was paralleled by a higher rate of SCAT lipolysis reflected by dialysate glycerol, plasma glycerol, and fatty acids (FA) levels (p < 0.001). Of note, we observed a significant relationship between whole-body fat oxidation and dialysate glycerol in both sessions (r (2) = 0.33, p = 0.02). In conclusion, this study highlights the limiting role of lipolysis and plasma FA availability to whole-body fat oxidation during exercise in endurance-trained subjects. This study shows that adipose tissue lipolysis is a determinant of fuel selection during exercise in healthy subjects.

Serum atrial natriuretic peptide level inversely associates with metabolic syndrome in older adults

AIM

Atrial natriuretic peptide (ANP) is a potent lipolytic agent that acts in adipose tissue. Low levels of ANP might lead to reduced lipolysis and excessive weight gain, which could be one of the biological alterations that contribute to the development of obesity. The aim of the present study was to evaluate the relationship between metabolic syndrome and fasting serum ANP concentrations in older adults.

METHODS

Fasting blood samples were obtained from 90 older adults. Metabolic syndrome and its components were defined using diagnostic criteria from the International Diabetes Federation.

RESULTS

A total of 40 older adults (44.4%) had metabolic syndrome. Fasting ANP level was negatively correlated with metabolic syndrome (P = 0.015). Univariate linear regression analysis showed that high-density lipoprotein cholesterol (P < 0.001) was positively correlated with serum logANP levels, whereas waist circumference (P = 0.001) and body fat mass (P = 0.002) were negatively correlated with fasting serum logANP levels. Multivariate forward stepwise linear regression analysis of the significant variables showed that high-density lipoprotein cholesterol (β = 0.419, R(2) = 0.268, P < 0.001) and body fat mass (β = -0.396, R(2) = 0.154, P = 0.002) were independent predictors of fasting serum logANP levels in geriatric persons.

CONCLUSIONS

Serum ANP levels were reduced in geriatric persons affected by metabolic syndrome. Body fat mass and high-density lipoprotein cholesterol were independent predictors of fasting serum ANP levels in older adults.

Inverse association of long-acting natriuretic peptide with metabolic syndrome in congestive heart failure patients

AIMS

Long-acting natriuretic peptide (LANP) is one of the peptide hormones in atrial natriuretic peptide (ANP) pro-hormone. Low levels of natriuretic peptide may lead to reduced lipolysis and excessive weight gain in obese patients. The aim of this study was to investigate the relationship between fasting serum LANP level and the metabolic syndrome (MetS) among congestive heart failure (CHF) patients.

METHODS

Fasting blood samples were obtained from 186 patients with normal renal function in cardiac clinic outpatients. CHF defined by the American College of Cardiology Foundation and the American Heart Association 2005 Guidelines. MetS and its components were defined using diagnostic criteria from the International Diabetes Federation.

RESULTS

Ninety-eight patients (52.7%) had CHF. There was a tendency of increased fasting LANP levels as the NYHA CHF functional classes increased (p = 0.002). Forty-six of the CHF patients (46.9%) had MetS. Fasting LANP level negatively correlated with MetS among CHF patients (p < 0.001). Univariate linear regression analysis showed that BUN (p = 0.026) positively correlated with fasting serum LANP levels, while body weight (p = 0.009), BMI (p = 0.004), homeostasis model assessment of insulin resistance (HOMA-IR; p = 0.024) and HOMA-β (p = 0.001) negatively correlated with fasting serum LANP levels among the CHF patients. Multivariate forward stepwise linear regression analysis of the significant variables showed that the HOMA-β (R2 change = 0.292, p < 0.001) and HOMA-IR (R2 change = 0.081, p = 0.019) were independent predictors of fasting serum LANP levels in CHF patients.

CONCLUSIONS

LANP level is significantly reduced in CHF patients affected by MetS. HOMA-β and HOMA-IR were independent predictors of serum LANP levels in CHF patients.

Low serum long-acting natriuretic peptide level correlates with metabolic syndrome in hypertensive patients: a cross-sectional study

BACKGROUND AND AIMS

Long-acting natriuretic peptide (LANP) is one of the peptide hormones in atrial natriuretic peptide (ANP) prohormone. Its biological properties are blood pressure regulation, maintenance of plasma volume and anticancer effects. The aim of this study was to evaluate the relationship between metabolic syndrome (MetS) and fasting serum LANP concentration in hypertensive patients.

METHODS

Fasting blood samples were obtained from 224 patients with or without hypertension. MetS and its components were defined using diagnostic criteria from the International Diabetes Federation.

RESULTS

Eighty-eight hypertensive patients (59.5 %) had MetS. Hypertensive patients with MetS had higher body weight (p = 0.003), waist circumference (p = 0.003), body mass index (p = 0.002), triglyceride concentrations (p = 0.029), insulin levels (p = 0.001), HOMA-IR (p <0.003) and HOMA-β (p = 0.049) and lower HDL-C concentrations (p = 0.001), LANP levels (p = 0.012) than those without MetS. The univariable linear regression analysis showed that age (p = 0.038) and the BUN concentration (p = 0.022) were positively correlated with the serum LANP levels, whereas the insulin level (p = 0.001), HOMA-IR (p = 0.004), and HOMA-β (p = 0.001) were negatively correlated with the fasting serum LANP levels among the hypertensive patients. Multivariable forward stepwise linear regression analysis of the significant variables showed that the HOMA-β (β = -0.387, R(2) = 0.141, p <0.001) was an independent predictor of fasting serum LANP levels in hypertensive patients.

CONCLUSIONS

LANP level is significantly reduced in hypertensive patients affected by MetS and is negatively related to pancreatic beta cell function in hypertensive patients.

Adipose tissue biology and cardiomyopathy: translational implications

It is epidemiologically established that obesity is frequently associated with the metabolic syndrome and poses an increased risk for the development of type 2 diabetes mellitus and cardiovascular disease. The molecular links that connect the phenomenon of obesity, per se, with insulin resistance and cardiovascular disease are still not fully elucidated. It is increasingly apparent that fully functional adipose tissue can be cardioprotective by reducing lipotoxic effects in other peripheral tissues and by maintaining a healthy balance of critical adipokines, thereby allowing the heart to maintain its full metabolic flexibility. The present review highlights both basic and clinical findings that emphasize the complex interplay of adipose tissue physiology and adipokine-mediated effects on the heart exerted by either direct effects on cardiac myocytes or indirect actions via central mechanisms through sympathetic outflow to the heart.

Prospective evaluation of B-type natriuretic peptide concentrations and the risk of type 2 diabetes in women

BACKGROUND

Animal data suggest that natriuretic peptides play an important role in energy metabolism, but prospective studies evaluating a relationship between these peptides and type 2 diabetes mellitus (T2DM) in humans are few and results are conflicting.

METHODS

We used a prospective case-cohort approach (n = 491 T2DM cases, n = 561 reference subcohort) within the Women's Health Study to evaluate baseline N-terminal pro-B-type natriuretic peptide (NT-proBNP) concentrations and the risk of incident T2DM. We also tested for associations between 4 common variants in the natriuretic peptide A and B genes (NPPA and NPPB) and NT-proBNP concentrations (n = 458) and incident T2DM (n = 1372 cases among 22 607 women).

RESULTS

Case subjects had higher median baseline body mass index (29.4 vs 25.0 kg/m(2), P < 0.001) and lower baseline median (interquartile range) NT-proBNP concentrations [46.8 ng/L (26.1-83.2) vs 66.7 ng/L (39.3-124.7), P < 0.001]. In proportional hazards models adjusting for established diabetes risk factors, women in the highest quartile of baseline NT-proBNP concentration (≥ 117.4 ng/L) had a 49% reduction in risk of T2DM [hazard ratio (HR) 0.51, 0.30-0.86, P = 0.01] relative to those in the lowest quartile. Two of the 4 tested variants in NPPA and NPPB (rs632793, rs198389) were associated with increased NT-proBNP concentrations and reduced risk of T2DM. For example, each copy of the minor allele of rs632793 was associated with increased NT-proBNP [β (SE) = 0.201 (0.063), P < 0.01] and decreased T2DM risk (HR 0.91, 0.84-0.989, P = 0.026).

CONCLUSIONS

NT-proBNP concentrations that are high, but still within the reference interval, associate with reduced risk of incident diabetes in women and support a favorable role for natriuretic peptides in the prevention of T2DM.

Fasting long-acting natriuretic peptide correlates inversely with metabolic syndrome in kidney transplant patients

The metabolic syndrome (MetS) is a risk factor for posttransplant diabetes mellitus, chronic graft dysfunction, graft loss, occurrence of atherosclerotic events, and patient death among kidney transplantation patients. Long-acting natriuretic peptide (LANP) is among the peptide hormones in atrial natriuretic peptide prohormone. Low levels of natriuretic peptide may lead to reduced lipolysis and excessive weight gain in obese patients. This study was undertaken to evaluate the relationship between MetS and fasting serum LANP concentration among kidney transplanted patients. Fasting blood samples were obtained from 69 kidney recipients. The MetS and its components were defined using the diagnostic criteria of the International Diabetes Federation. Fasting LANP levels were measured using a commercial enzyme immunoassay kit. The prevalence rate of MetS was 20.3% (14/69). Fasting LANP level negatively correlated with MetS among these patients (P = .010). Using univariate linear regression analysis, serum LANP values were negatively correlated with hemoglobin (r = -0.252; P = .037), and positively correlated with blood urea nitrogen (r = 0.254; P = .035) and creatinine (r = 0.311; P = .009). Multivariate forward stepwise linear regression analysis of the significant variables revealed that creatinine (R(2) change = 0.097; P = .009) was an independent predictor of fasting serum LANP concentration among kidney transplanted patients. Serum LANP concentration correlates inversely with MetS; for these patients, creatinine is an independent predictor of the serum LANP value.

Association of 2238T>C polymorphism of the atrial natriuretic peptide gene with coronary artery disease in Afro-Caribbeans with type 2 diabetes

BACKGROUND

The atrial natriuretic peptide (ANP) is known mainly for its effects on kidney function and blood pressure homeostasis. We investigated the association between two ANP polymorphisms and pre-existing coronary artery disease (CAD) in patients of African descent with type 2 diabetes (T2D).

METHODS

We conducted a cross-sectional and retrospective study of 218 volunteer Afro-Caribbean patients with T2D. Two polymorphisms (rs5064, 708C>T; and rs5065, 2238T>C) of ANP were genotyped using PCR-restriction fragment length polymorphism analysis. ANCOVA, χ2-test, and logistic regression were used for statistical analysis.

RESULTS

Among these patients (92 men; 128 women), 67 (30.7%) had CAD, of whom 75% had had myocardial infarction. The frequency of rs5065-C carriers (TC/CC) was significantly lower in patients with CAD than in those without CAD (24 vs. 41%, P = 0.01). The frequency of hypertension did not differ significantly according to genotype. Univariate logistic regression revealed that male sex, age, dyslipidemia, hypertension, and rs5065-C carrier status were associated significantly with CAD. After adjustment for the variables of interest, the odds ratio (ORs) of CAD for rs5065-C carriers (TC/CC) was 0.50 (0.26-0.96; P = 0.038). No association was found between the rs5064 (708C>T) single-nucleotide polymorphisms (SNPs) and pre-existing CAD or cardiovascular risk factors.

CONCLUSIONS

The ANP rs5065 (2238T>C) C allele seems to exert a protective effect against CAD in T2D patients of African descent. The relevance of ANP polymorphisms for CAD should be determined in different populations.

Investigation on the protective effects of cranberry against the DNA damage induced by benzo[a]pyrene

There are few reports that demonstrate the antigenotoxic potential of cranberries. Although the types of berry fruits consumed worldwide are many, this paper focuses on cranberries that are commonly consumed in Mexico (Vaccinium macrocarpon species). The purpose of the present study is to determine whether cranberry ethanolic extract (CEE) can prevent the DNA damage produced by benzo[a]pyrene (B[a]P) using an in vivo mouse peripheral blood micronucleus assay. The experimental groups were organized as follows: a negative control group (without treatment), a positive group treated with B[a]P (200 mg/kg), a group administered with 800 mg/kg of CEE, and three groups treated with B[a]P and CEE (200, 400, and 800 mg/kg) respectively. The CEE and benzo[a]pyrene were administered orally for a week, on a daily basis. During this period the body weight, the feed intake, and the determination of antigenotoxic potential were quantified. At the end of this period, we continued with the same determinations for one week more (recovery period) but anymore administration of the substances. The animals treated with B[a]P showed a weight increase after the first week of administration. The same phenomenon was observed in the lots combined with B[a]P and CEE (low and medium doses). The dose of 800 mg/kg of CEE showed similar values to the control group at the end of the treatment period. In the second part of the assay, when the substances were not administered, these experimental groups regained their normal weight. The dose of CEE (800 mg/kg) was not genotoxic nor cytotoxic. On the contrary, the B[a]P increases the frequency of micronucleated normochromatic erythrocytes (MNNE) and reduces the rate of polychromatic erythrocytes (PE) at the end of the treatment period. With respect to the combined lots, a significant decrease in the MN rate was observed from the sixth to the eighth day of treatment with the two high doses applied; the highest protection (60%) was obtained with 800 mg/kg of CEE. The same dose showed an anticytotoxic effect which corresponded to an improvement of 62.5% in relation to the animals administered with the B[a]P. In the second period, all groups reached values that have been seen in the control group animals. Our results suggest that the inhibition of clastogenicity of the cranberry ethanolic extract against B[a]P is related to the antioxidant capacity of the combination of phytochemicals present in its chemical composition.

Effects of chronic elevation of atrial natriuretic peptide and free fatty acid levels in the induction of type 2 diabetes mellitus and insulin resistance in patients with mitral valve disease

BACKGROUND AND AIMS

The relationship between atrial natriuretic peptide (ANP), increased free fatty acid (FFA) and insulin resistance in patients with mitral valve disease (MVD), a group characterised by elevated atrial pressure and increased ANP levels, is not defined. The present study was performed to evaluate, in MVD patients, the relationship between increased ANP and FFA levels and insulin resistance and the role of mitral valve replacement/repair in ameliorating these metabolic alterations. Conversely, coronary heart disease (CHD) patients were evaluated before and after coronary artery bypass grafting (CABG), since they are known to be insulin resistant in the presence of chronic FFA increase.

METHODS AND RESULTS

Fifty MVD patients and 55 CHD patients were studied before and 2 months after surgery and compared with 166 normal subjects. Before surgery, 56% of MVD patients had impaired glucose tolerance or newly diagnosed type 2 diabetes after a standard oral glucose load and this percentage decreased to 46% after surgery. In CHD, impaired glucose tolerance (IGT) or newly diagnosed type 2 diabetic patients were 67% of patients before and after CABG. In MVD, left atrial (LA) volume, ANP, FFA incremental area and insulin levels were higher and Insulin Sensitivity (IS) index significantly reduced while after surgery, LA volume, ANP and FFA significantly decreased and IS index significantly improved. In CHD, insulin resistance and hyperinsulinaemia were present both before and after surgery with increased tumour necrosis factor (TNF)-α and interleukin (IL)-6 levels.

CONCLUSION

In MVD, a higher degree of abnormal glucose tolerance and insulin resistance are associated to increased levels of ANP and FFA, while these metabolic alterations are improved by mitral valve replacement/repair surgery. Clinical Trial.gov registration number NCT 00520962.

Cachexia and sarcopenia: emerging syndromes of importance in dogs and cats

Cachexia is the loss of lean body mass (LBM) that affects a large proportion of dogs and cats with congestive heart failure (CHF), chronic kidney disease (CKD), cancer, and a variety of other chronic diseases. Sarcopenia, the loss of LBM that occurs with aging, is a related syndrome, although sarcopenia occurs in the absence of disease. As many of the diseases associated with muscle loss are more common in aging, cachexia and sarcopenia often are concurrent problems. Both cachexia and sarcopenia have important clinical implications because they are associated with increased morbidity and mortality. The pathophysiology of these 2 syndromes is complex and multifactorial, but recent studies have provided new information that has helped to clarify mechanisms and identify potential new targets for treatment. Newly identified mechanisms and pathways that mediate cachexia appear to act by increasing energy requirements, decreasing energy intake, impairing nutrient absorption, and causing metabolic alterations. Whereas cachexia and sarcopenia are important areas of research for drug development in people, they are only beginning to be recognized in veterinary medicine. Greater awareness and earlier diagnosis will help provide practical approaches to managing body weight and lean tissue in dogs and cats, as well as more directed targets for treatment.

Overexpression of constitutively active PKG-I protects female, but not male mice from diet-induced obesity

Cyclic guanosine monophosphate (cGMP)-dependent protein kinase I (PKG-I) is a multifunctional protein. The direct effects of PKG-I activation on energy homeostasis and obesity development are not well understood. Herein, we generated transgenic mice with expression of the constitutively active PKG-I in adipose tissue as well as in other tissues. Male and female PKG-I overexpressing mice were fed a low-fat (LF) or high-fat (HF) diet for 16 weeks. HF-fed female PKG-I transgenic mice had decreased body weight gain, lower percentage of body fat, and improved glucose tolerance compared to HF-fed wild-type (WT) controls. In contrast, male transgenic PKG-I mice were not resistant to the development of HF-diet-induced obesity, and exhibited similar levels of adiposity and glucose intolerance as HF-fed WT controls. Furthermore, we found that HF-fed female transgenic PKG-I mice had increased energy expenditure and cold-induced adaptive thermogenesis compared to HF-fed WT controls, which was associated with increased expression of uncoupling protein-1 (UCP1) in brown adipose tissue (BAT). In addition, the rates of lipolysis in white adipose tissue (WAT) were also increased in female transgenic PKG-I mice compared to WT controls due to increased phosphorylation of hormone-sensitive lipase (HSL). However, in male mice, adaptive thermogenesis or WAT lipolysis was similar between transgenic PKG-I mice and WT controls. Together, these data demonstrate sex differences in effects of PKG-I activation on the regulation of adipose tissue function and its contribution to diet induced obesity.

Relationship between N-terminal pro-B-type natriuretic peptide levels and metabolic syndrome

INTRODUCTION

Previous studies have shown that obese individuals have reduced natriuretic peptide levels. But conflicting data exist on the relation of natriuretic peptide levels to other metabolic risk factors.

MATERIAL AND METHODS

We investigated the relationship between plasma N-terminal pro-B-type natriuretic peptide levels (NT-proBNP) and metabolic syndrome (MetS) and metabolic risk factors in 469 patients free of heart failure. Two hundred thirty diagnosed MetS cases and 239 non-MetS cases were included in this study. Echocardiography examinations were performed and left ventricular mass index was calculated according to the Devereux correction formula. NT-proBNP was measured by electrochemiluminescence. The log-transformed NT-proBNP levels were used for abnormal distribution. Multiple linear regression analysis was performed to assess the association between levels of NT-proBNP and metabolic factors. Covariance analysis was used for group comparisons.

RESULTS

Log NT-proBNP levels were independently related to age, gender, body mass index, systolic blood pressure, diastolic blood pressure, fasting blood glucose, triglyceride, high density lipoprotein cholesterol, low density lipoprotein cholesterol, left ventricular mass index and left ventricular ejection fraction in multiple linear regression analysis (p < 0.05). Adjusted log NT-proBNP levels were lower in persons with MetS compared with those without MetS (p < 0.05). Individuals with hyperlipidaemia, elevated body mass index, diastolic blood pressure and fasting plasma glucose had lower levels of log NT-proBNP than those without MetS (p < 0.05).

CONCLUSIONS

There is a relationship between metabolic components and lower plasma NT-proBNP concentration. These findings raise the possibility that reduced plasma NT-proBNP levels are a manifestation of MetS, which might possess significant clinical and pathophysiological implications.

Effect of a 1-hour single bout of moderate-intensity exercise on fat oxidation kinetics

The present study aimed to examine the effects of a prior 1-hour continuous exercise bout (CONT) at an intensity (Fat(max)) that elicits the maximal fat oxidation (MFO) on the fat oxidation kinetics during a subsequent submaximal incremental test (IncrC). Twenty moderately trained subjects (9 men and 11 women) performed a graded test on a treadmill (Incr), with 3-minute stages and 1-km.h(-1) increments. Fat oxidation was measured using indirect calorimetry and plotted as a function of exercise intensity. A mathematical model (SIN) including 3 independent variables (dilatation, symmetry, and translation) was used to characterize the shape of fat oxidation kinetics and to determine Fat(max) and MFO. On a second visit, the subjects performed CONT at Fat(max) followed by IncrC. After CONT performed at 57% +/- 3% (means +/- SE) maximal oxygen uptake (Vo(2max)), the respiratory exchange ratio during IncrC was lower at every stage compared with Incr (P < .05). Fat(max) (56.4% +/- 2.3% vs 51.5% +/- 2.4% Vo(2max), P = .013), MFO (0.50 +/- 0.03 vs 0.40 +/- 0.03 g.min(-1), P < .001), and fat oxidation rates from 35% to 70% Vo(2max) (P < .05) were significantly greater during IncrC compared with Incr. However, dilatation and translation were not significantly different (P > .05), whereas symmetry tended to be greater in IncrC (P = .096). This study showed that the prior 1-hour continuous moderate-intensity exercise bout increased Fat(max), MFO, and fat oxidation rates over a wide range of intensities during the postexercise incremental test. Moreover, the shape of the postexercise fat oxidation kinetics tended to have a rightward asymmetry.