Hyperinsulinemia correlates with low levels of plasma B-type natriuretic peptide in Japanese men irrespective of fat distribution

Effect of insulin on natriuretic peptide gene expression in porcine heart

Gut hormones affect cardiac function and contractility. In this study, we examined whether insulin affects the cardiac atrial natriuretic peptide (ANP) and B-type natriuretic peptide (BNP) gene expression and release of proANP-derived peptides in pigs. Anaesthetized pigs were included in an experimental study comparing the effect of hyperinsulinemia in 15 pigs submitted to two different protocols versus 11 control pigs receiving saline infusion. Phosphorylation of Akt on Thr308 was determined by western blotting with a pAkt-Thr308 antibody. The mRNA contents of ANP and BNP were determined with real-time PCR; plasma and cardiac tissue proANP was measured with an immunoluminometric assay targeted against the mid-region of the propeptide and a processing-independent assay. Insulin stimulation increased phosphorylation of Akt Thr308 in both left atrium and left ventricle of porcine hearts (p < 0.005). No change was observed in ANP and BNP mRNA contents in the right or left atrium. BNP mRNA contents in the left ventricle, however, decreased 3-fold (p = 0.02) compared to control animals, whereas the BNP mRNA content in the right ventricle as well as ANP mRNA content in the right and left ventricle did not change following hyperinsulinemia. Moreover, the peptide contents did not change in the four cardiac chambers. Finally, proANP concentrations in plasma did not change during the insulin infusion compared to the control animals. These results suggest that insulin does not have direct effect on atrial natriuretic peptide expression but may have a role in the left ventricle.

Association Between Cardiac Natriuretic Peptides and Lipid Profile: a Systematic Review and Meta-Analysis

Cardiac natriuretic peptides (NPs) play a fundamental role in maintaining cardiovascular (CV) and renal homeostasis. Moreover, they also affect glucose and lipid metabolism. We performed a systematic review and meta-analysis of studies investigating the association of NPs with serum lipid profile. A PubMed and Scopus search (2005–2018) revealed 48 studies reporting the association between NPs and components of lipid profile [total cholesterol (TC), low-density lipoprotein cholesterol (LDLc), high-density lipoprotein cholesterol (HDLc) and triglycerides (TG)]. Despite high inconsistency across studies, NPs levels were inversely associated with TC [k = 32; pooled r = −0.09; I² = 90.26%], LDLc [k = 31; pooled r = −0.09; I² = 82.38%] and TG [k = 46; pooled r = −0.11; I² = 94.14%], while they were directly associated with HDLc [k = 41; pooled r = 0.06; I² = 87.94%]. The relationship with LDLc, HDLc and TG lost significance if only studies on special populations (works including subjects with relevant acute or chronic conditions that could have significantly affected the circulating levels of NPs or lipid profile) or low-quality studies were taken into account. The present study highlights an association between higher NP levels and a favorable lipid profile. This confirms and extends our understanding of the metabolic properties of cardiac NPs and their potential in CV prevention.

Regulation of B-type natriuretic peptide synthesis by insulin in obesity in male mice

Human studies suggest that insulin resistance and obesity are associated with a decrease in B-type natriuretic peptide (BNP) plasma concentrations. The objective of the study was to gain insights into the mechanisms involved in the association between insulin resistance and decreased BNP plasma concentrations. Mice fed a high-fat, high-fructose (HFHF) diet for 4 weeks developed mild obesity and systemic insulin resistance. Elevated plasma concentrations of insulin, glucose and triglycerides were noted. The HFHF diet was also associated with myocardial insulin resistance, characterized by an impaired response of the phosphoinositide 3-kinase-AKT (PI3K-AKT) pathway to insulin in the left ventricle. Myocardial BNP expression and protein were decreased in HFHF-fed mice compared with control animals. Exposure of cardiomyocytes to 100 nm insulin activated PI3K-AKT signalling (15 min) and induced a 1.9 ± 0.3-fold increase in BNP gene expression (6 h). Prolonged exposure of cardiomyocytes to a high insulin concentration (100 nm) for 48 h induced insulin resistance, characterized by an impaired response of the PI3K-AKT signalling pathway and a decreased response of the BNP gene expression to insulin. The decreased response in BNP gene expression was reproduced by treating cardiomyocytes for 7 h with a PI3-kinase inhibitor (wortmannin). In conclusion, HFHF diet in vivo, prolonged exposure to an elevated concentration of insulin or inhibition of the PI3K-AKT pathway in vitro all decrease BNP mRNA levels; this decrease may in turn contribute to the decreased BNP peptide concentrations in plasma observed in insulin-resistant individuals.

Examination of the brain natriuretic peptide rs198389 single-nucleotide polymorphism on type 2 diabetes mellitus and related phenotypes in an Algerian population

BACKGROUND

In European populations, the NPPB rs198389 single nucleotide polymorphism (SNP) is associated with a reduced risk of type 2 diabetes mellitus (T2DM). We investigated the putative associations between NPPB rs198389, the T2DM risk and quantitative metabolic traits in an Algerian population.

METHODS

The association analysis was performed as a T2DM case-control study (with 78 cases and 645 controls) nested into the ISOR population-based study.

RESULTS

The NPPB rs198389 SNP was not associated with T2DM (odds ratio (OR) [95% confidence interval (CI)]=0.73 [0.51-1.04], p=0.08). However, the C allele was associated with lower fasting plasma insulin levels (p=0.05) and a lower homeostatic model assessment insulin resistance index (p=0.05) in non-diabetic individuals.

CONCLUSION

The NPPB rs198389 SNP might modulate fasting insulin levels in an Algerian population.

Metabolic rather than body composition measurements are associated with lower serum natriuretic peptide concentrations in normal weight and obese men

BACKGROUND

Several studies have shown that obese persons have lower circulating natriuretic peptide (NP) concentrations. The cause of the relative NP deficiency seen in obese persons is poorly understood, although variation in body composition and metabolic abnormalities has been suggested to play a role. Thus, the aim of this study was to assess whether variation in circulating NP concentrations would be associated with differences in metabolic disturbances rather than with differences in body composition.

METHODS

In 27 normal weight men (body mass index (BMI) = 20.0-24.9kg/m(2)) and 103 obese men (BMI ≥ 30kg/m(2)), we determined body composition (total, android, and gynoid fat mass) by dual energy x-ray absorptiometry scanning, and we measured fasting serum concentrations of midregional proatrial NP (MR-proANP) and insulin, as well as fasting plasma glucose concentrations.

RESULTS

Mean weight ± SD was 74.9±6.7kg in the normal weight men and 106.1±10.8kg in obese men. Applying multiple regressions, adjusting for age and weight status (normal weight vs. obese), serum MR-proANP concentrations were significantly inversely associated with serum insulin concentrations (β = -0.39; P < 0.0001) and plasma glucose concentrations (β = -0.21; P = 0.02) but not with total (β = 0.00), android (β = -0.01), or gynoid (β = 0.03) fat mass percentage (P > 0.76). No significant interaction effects between metabolic measurements or body composition measurements and weight status on MR-proANP concentrations were found (P > 0.08).

CONCLUSIONS

In normal weight and obese men, lower circulating NP concentrations are associated with higher insulin and glucose concentrations and not with the proportion of total fat mass or the distribution of fat mass.

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.

Cardiac production of B-type natriuretic peptide is inversely related to the plasma level of free fatty acids in obese individuals - possible involvement of the insulin resistance -

B-type natriuretic peptide (BNP) is produced by the heart and its plasma level is increased with the severity of left ventricular (LV) dysfunction/hypertrophy. The normal heart preferentially utilizes fatty acids as energy substrates. Plasma BNP levels are reported to be lower in obese individuals. We examined the relationship between BNP production and plasma free fatty acids (FFA), homeostasis model assessment of insulin resistance (HOMA-IR), and LV dysfunction/ hypertrophy. We examined the plasma BNP levels and FFA at the aortic root (AO) and coronary sinus (CS) as well as hemodynamic parameters in 62 patients (38 men and 24 women, 62.5±11.7 yrs) who underwent cardiac catheterization. Log BNP (AO) had a significant positive correlation with log BNP (CS-AO) (r=0.877, P<0.001). Log BNP(CS-AO) had a significant negative correlation with BMI (r=-0.558, P<0.001), waist circumference (WC) (r=-0.574, P<0.001), log FFA(AO) (r=-0.643, P<0.001), log triglyceride (r=-0.431, P<0.001), and log HOMA-IR (r=-0.463, P<0.001) and a significant positive correlation with left ventricular mass index (LVMI) (r=0.403, P=0.001). The multivariable regression analyses including log HOMA-IR, LVMI, and age as an independent variable revealed that HOMA-IR and LVMI were significant predictors of log BNP (CS-AO) or BNP production (P=0.001 and 0.004, respectively). We conclude that plasma BNP levels are determined primarily by cardiac production and that insulin resistance is a significant predictor of cardiac BNP production independent of LV hypertrophy in obese individuals.

Plasma NT-proBNP and white matter hyperintensities in type 2 diabetic patients

Abstract

Elevated plasma N-terminal (NT)-proBNP from the heart as well as white matter hyperintensities (WMH) in the brain predict cardiovascular (CV) mortality in the general population. The cause of poor prognosis associated with elevated P-NT-proBNP is not known but WMH precede strokes in high risk populations. We assessed the association between P-NT-proBNP and WMH or brain atrophy measured with magnetic resonance imaging (MRI) in type 2 diabetic patients, and age-matched controls.

Methods and results

We measured P-NT-proBNP(ng/l) in 20 diabetic patients without prior stroke but with(n = 10) or without(n = 10) asymptomatic coronary artery disease(CAD) in order to include patients with a wide-ranging CV risk profile. All patients and 26 controls had a 3D MRI and brain volumes(ml) with WMH and brain parenchymal fraction(BPF), an indicator of brain atrophy, were determined.

P-NT-proBNP was associated with WMH in linear regression analysis adjusted for CV risk factors(r = 0.94, p = 0.001) and with BPF in univariate analysis(r = 0.57, p = 0.009). Patients divided into groups of increased P-NT-proBNP levels were paralleled with increased WMH volumes(geometric mean[SD];(2.86[5.11] ml and 0.76[2.49] ml compared to patients with low P-NT-proBNP 0.20[2.28] ml, p = 0.003)) and also when adjusted for age, sex and presence of CAD(p = 0.017). The association was strengthened by CV risk factors and we did not find a common heart or brain specific driver of both P-NT-proBNP and WMH. Patients and particular patients with CAD had higher WMH, however no longer after adjustment for age and sex.

Conclusion

P-NT-proBNP was associated with WMH in type 2 diabetic patients, suggesting a linkage between heart and brain disease.