Calorie restriction reduced blood pressure in obesity hypertensives by improvement of autonomic nerve activity and insulin sensitivity

Sodium intake and high blood pressure among adults on caloric deficit: a multi-year cross-sectional analysis of the U.S. population, 2007-2018

Small studies have shown reduced sodium-sensitivity of blood pressure in obese adolescents on a caloric deficit. We aimed to explore the association between mean daily sodium intake and prevalent hypertension among a nationally representative sample of U.S. adults on a calorie deficit. We used a design-based regression model to explore the association between sodium intake and prevalent hypertension. We also conducted sensitivity analyses using multiple imputation chained equations and propensity score matching. We also measured the effect of a binary exposure derived from the widely recommended threshold of 2.3 grams of sodium intake per day. Among 5756 individuals, we did not detect any significant association between increased sodium and the odds of hypertension (OR: 0.97; 95% CI: 0.90; 1.05). All our sensitivity analyses are consistent with our main findings. People on a calorie deficit-a component of healthy weight loss-without malnutrition saw no benefit in reduced sodium intake to lower blood pressure. These results highlight the need to explore new population-specific strategies for sodium intake reduction, including new dietary prescription approaches to improve dietary adherence and reduce the risk associated with sodium-deficient diets.

Assessing Genders Separately in Nondiabetic Persons Regarding Links Between Insulin Resistance and Fat Mass With Elements Related to the Metabolic Syndrome

OBJECTIVE

Initial results gathered from previously published observations dealing with nondiabetic volunteers reveal that both the fasting blood glucose (FBG) level employed as a surrogate for insulin resistance (IR) and the amount of body fat mass (FM) correlate significantly with the strength and pathological direction of many harmful elements making up the metabolic syndrome (MS). These initial results were obtained using combined data from both females and males. How the two markers correlate with specific metabolic parameters in each gender separately was not established.

METHOD

Baseline data from more than 700 volunteers were examined mainly using correlations to compare whether the breadth of IR estimated by FBG levels and/or the accumulation of body FM on the early development and progression of many chronic metabolic derangements differ to any meaningful extent between nondiabetic females and males.

RESULTS

The following significant positive correlations were found in the data on females employing either FBG or FM as independent variables regarding development of elements associated with MS: in body composition (scale weight, fat free mass [FFM]); in blood chemistries (triglycerides, high-sensitivity C-reactive protein [hsCRP], alanine aminotransferase [ALT]); and in blood counts (white blood cells [WBC], neutrophils). Also consistent with MS, high-density lipoprotein cholesterol levels declined significantly. In males, findings with FBG as the independent variable differ from females in some respects. These major exceptions are lack of significant correlations with FFM and high-density lipoprotein cholesterol as well as a weaker link with ALT. Despite a positive hsCRP linkage, a poorer response of WBC and neutrophils appeared in males when correlations were made. The latter disassociations disappeared when FM replaced FBG as the independent variable.

CONCLUSIONS

Progression of many chronic metabolic derangements differ only slightly in females and males.

Does bariatric surgery improve cardiac autonomic modulation assessed by heart rate variability? A systematic review

Our study aimed to explore the influence of bariatric surgery (BS) on heart rate (HR) variability (HRV) through a systematic review. Manuscripts were selected based on electronic searches of the MEDLINE, EMBASE, and CINAHL databases from the inception of each database up to year 2020, and followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) protocol. Searching of these studies was systematized using the Population Intervention Comparison Outcome Study Design strategy. We selected randomized and nonrandomized controlled trials and cohorts from prospective studies that reported the influence of BS on HRV. We assessed the quality rating using the Black and Downs questionnaire. Following the screening and eligibility stages, 14 studies were included in the review. All studies agreed that BS promotes an increase in parasympathetic HR control and HRV and a decrease in HR. Yet the literature does not provide evidence that these outcomes are directly caused by the surgical procedure. There is limited evidence to support that patients with type 2 diabetes have greater improvement in HRV as an interim measure, to individuals without. The decrease in insulin resistance was correlated with the increase in HRV in some studies, but, other studies are unsupportive of this outcome. Improvements in 2 metabolic parameters (e.g., leptin, N-terminal pro B-type natriuretic peptide) were connected with superior increases in HRV. This review demonstrated that BS promotes an increase in HRV, indicating improved autonomic control of HR.

Effects of Caloric Restriction Diet on Arterial Hypertension and Endothelial Dysfunction

The most common manifestation of cardiovascular (CV) diseases is the presence of arterial hypertension (AH), which impacts on endothelial dysfunction. CV risk is associated with high values of systolic and diastolic blood pressure and depends on the presence of risk factors, both modifiable and not modifiable, such as overweight, obesity, physical exercise, smoking, age, family history, and gender. The main target organs affected by AH are the heart, brain, vessels, kidneys, and eye retina. AH onset can be counteracted or delayed by adopting a proper diet, characterized by a low saturated fat and sodium intake, a high fruit and vegetable intake, a moderate alcohol consumption, and achieving and maintaining over time the ideal body weight. In this review, we analyzed how a new nutritional approach, named caloric restriction diet (CRD), can provide a significant reduction in blood pressure values and an improvement of the endothelial dysfunction. In fact, CRD is able to counteract aging and delay the onset of CV and neurodegenerative diseases through the reduction of body fat mass, systolic and diastolic values, free radicals production, and oxidative stress. Currently, there are few studies on CRD effects in the long term, and it would be advisable to perform observational studies with longer follow-up.

Pancreatic source of protease activity in the spontaneously hypertensive rat and its reduction during temporary food restriction

OBJECTIVE

The mechanisms underlying cell and organ dysfunctions in hypertension are uncertain. The spontaneously hypertensive rat (SHR) has elevated levels of unchecked degrading proteases compared to the control Wistar Kyoto (WKY) rat. The extracellular proteases destroy membrane receptors leading to cell dysfunctions, including arteriolar constriction and elevated blood pressure. Our goal was to identify potential sources of the uncontrolled enzymatic activity.

METHODS

Zymographic and digital immunohistochemical measurements in SHR pancreas and intestine were obtained as part of the digestive system with high levels of degrading enzymes.

OBJECTIVE

The results showed that SHRs have significantly higher protease activity than WKY in pancreas (22.04 ± 9.01 vs 13.02 ± 3.92 casein fluorescence intensity unit; P < 0.05) and pancreatic venules (0.011 ± 0.003 vs 0.005 ± 0.003 trypsin absorbance; P < 0.05) as well as in venous blood (71.07 ± 13.92 vs 36.44 ± 16.59 casein fluorescence intensity unit; P < 0.05). The enzymatic activity is contributed by trypsin and chymotrypsin. Furthermore, a decrease of these enzyme activity levels achieved during a short-term fasting period is associated with a reduction in systolic blood pressurein SHR (135 ± 8 mm Hg vs 124 ± 7 mm Hg; P < 0.05).

CONCLUSIONS

The results suggest the pancreas of the SHR is a potential source for serine proteases leaking into the circulation and contributing to its protease activity.

Caloric restriction improves glucose homeostasis, yet increases cardiometabolic risk in caveolin-1-deficient mice

BACKGROUND AND PURPOSE

The plasma membrane protein caveolin-1 (CAV-1) has been shown to be involved in modulating glucose homeostasis and the actions of the renin-angiotensin-aldosterone system (RAAS). Caloric restriction (CR) is widely accepted as an effective therapeutic approach to improve insulin sensitivity and reduce the severity of diabetes. Recent data indicate that polymorphisms of the CAV-1 gene are strongly associated with insulin resistance, hypertension and metabolic abnormalities in non-obese individuals. Therefore, we sought to determine whether CR improves the metabolic and cardiovascular (CV) risk factors in the lean CAV-1 KO mice.

MATERIALS/METHODS

Twelve- to fourteen-week-old CAV-1 knockout (KO) and genetically matched wild-type (WT) male mice were randomized by genotype to one of two dietary regimens: ad libitum (ad lib) food intake or 40% CR for 4 weeks. Three weeks following the onset of dietary restriction, all groups were assessed for insulin sensitivity. At the end of the study, all groups were assessed for fasting glucose, insulin, HOMA-IR, lipids, corticosterone levels and blood pressure (BP). Aldosterone secretion was determined from acutely isolated Zona Glomerulosa cells.

RESULTS

We confirmed that the CAV-1 KO mice on the ad lib diet display a phenotype consistent with the cardiometabolic syndrome, as shown by higher systolic BP (SBP), plasma glucose, HOMA-IR and aldosterone levels despite lower body weight compared with WT mice on the ad lib diet. CAV-1 KO mice maintained their body weight on the ad lib diet, but had substantially greater weight loss with CR, as compared to caloric restricted WT mice. CR-mediated changes in weight were associated with dramatic improvements in glucose and insulin tolerance in both genotypes. These responses to CR, however, were more robust in CAV-1KO vs. WT mice and were accompanied by reductions in plasma glucose, insulin and HOMA-IR in CAV-1KO but not WT mice. Surprisingly, in the CAV-1 KO, but not in WT mice, CR was associated with increased SBP and aldosterone levels, suggesting that in CAV-1 KO mice CR induced an increase in some CV risk factors.

CONCLUSIONS

CR improved the metabolic phenotype in CAV-1 KO mice by increasing insulin sensitivity; nevertheless, this intervention also increased CV risk by inappropriate adaptive responses in the RAAS and BP.

Caloric Restriction and Its Effect on Blood Pressure, Heart Rate Variability and Arterial Stiffness and Dilatation: A Review of the Evidence

Essential hypertension, fast heart rate, low heart rate variability, sympathetic nervous system dominance over parasympathetic, arterial stiffness, endothelial dysfunction and poor flow-mediated arterial dilatation are all associated with cardiovascular mortality and morbidity. This review of randomised controlled trials and other studies demonstrates that caloric restriction (CR) is capable of significantly improving all these parameters, normalising blood pressure (BP) and allowing patients to discontinue antihypertensive medication, while never becoming hypotensive. CR appears to be effective regardless of age, gender, ethnicity, weight, body mass index (BMI) or a diagnosis of metabolic syndrome or type 2 diabetes, but the greatest benefit is usually observed in the sickest subjects and BP may continue to improve during the refeeding period. Exercise enhances the effects of CR only in hypertensive subjects. There is as yet no consensus on the mechanism of effect of CR and it may be multifactorial. Several studies have suggested that improvement in BP is related to improvement in insulin sensitivity, as well as increased nitric oxide production through improved endothelial function. In addition, CR is known to induce SIRT1, a nutrient sensor, which is linked to a number of beneficial effects in the body.

Ursolic Acid and Chronic Disease: An Overview of UA's Effects On Prevention and Treatment of Obesity and Cancer

Chronic diseases pose a worldwide problem and are only continuing to increase in incidence. Two major factors contributing to the increased incidence in chronic disease are a lack of physical activity and poor diet. As the link between diet and lifestyle and the increased incidence of chronic disease has been well established in the literature, novel preventive, and therapeutic methods should be aimed at naturally derived compounds such as ursolic acid (UA), the focus of this chapter. As chronic diseases, obesity and cancer share the common thread of inflammation and dysregulation of many related pathways, the focus here will be on these two chronic diseases. Significant evidence in the literature supports an important role for natural compounds such as UA in the prevention and treatment of chronic diseases like obesity and cancer, and here we have highlighted many of the ways UA has been shown to be a beneficial and versatile phytochemical.

Effect of a weight reduction program on baseline and stress-induced heart rate variability in children with obesity

OBJECTIVE

Autonomic dysregulation is a well-established feature in adults with obesity but not in children. Since this dysregulation could contribute to weight dynamics, this study aimed to compare autonomic regulation in children with obesity and normal-weight peers and to track autonomic status during weight reduction.

METHODS

Sixty children with obesity and 27 age- and sex-matched normal-weight healthy participants were included. Heart rate variability (HRV) was assessed at baseline and during a mental stress test and a subsequent recovery period. Children with obesity were investigated both upon admission and discharge.

RESULTS

Upon admission, no significant differences in HRV parameters were found for normal-weight participants and those with obesity. Inpatient treatment led to significant changes in HRV with increase in general variability (standard deviation of the normal-to-normal interval (SDNN), P < 0.001) as well as of parasympathetic regulation (root mean square successive difference (RMSSD) and high frequency power (logHF), P < 0.01). Children with obesity had sympathetic activation similar to normal-weight controls during mental stress with subsequent return to baseline values, and weight loss did not affect this profile.

CONCLUSIONS

A weight reduction program induced a change in autonomic activity in children with obesity toward parasympathetic dominance but had no influence on autonomic nervous system reactivity during stress conditions.

Enhanced insulin sensitivity mediated by adipose tissue browning perturbs islet morphology and hormone secretion in response to autonomic nervous activation in female mice

Insulin resistance results in a compensatory increase in insulin secretion to maintain normoglycemia. Conversely, high insulin sensitivity results in reduced insulin secretion to prevent hypoglycemia. The mechanisms for this inverse adaptation are not well understood. We utilized highly insulin-sensitive mice, due to adipocyte-specific overexpression of the FOXC2 transcription factor, to study mechanisms of the reversed islet adaptation to increased insulin sensitivity. We found that Foxc2TG mice responded to mild hyperglycemia with insulin secretion significantly lower than that of wild-type mice; however, when severe hyperglycemia was induced, Foxc2TG mice demonstrated insulin secretion equal to or greater than that of wild-type mice. In response to autonomic nervous activation by 2-deoxyglucose, the acute suppression of insulin seen in wild-type mice was absent in Foxc2TG mice, suggesting impaired sympathetic signaling to the islet. Basal glucagon was increased in Foxc2TG mice, but they displayed severely impaired glucagon responses to cholinergic and autonomic nervous stimuli. These data suggest that the autonomic nerves contribute to the islet adaptation to high insulin sensitivity, which is compatible with a neuro-adipo regulation of islet function being instrumental for maintaining glucose regulation.

Calorie restriction attenuates cardiac remodeling and diastolic dysfunction in a rat model of metabolic syndrome

Calorie restriction (CR) can modulate the features of obesity-related metabolic and cardiovascular diseases. We have recently characterized DahlS.Z-Lepr(fa)/Lepr(fa) (DS/obese) rats, derived from a cross between Dahl salt-sensitive and Zucker rats, as a new animal model of metabolic syndrome. DS/obese rats develop hypertension and manifest left ventricular remodeling and diastolic dysfunction, as well as increased cardiac oxidative stress and inflammation. We have now investigated the effects of CR on cardiac pathophysiology in DS/obese rats. DS/obese rats were fed either normal laboratory chow ad libitum or a calorie-restricted diet (65% of the average food intake for ad libitum) from 9 to 13 weeks. Age-matched homozygous lean (DahlS.Z-Lepr(+)/Lepr(+) or DS/lean) littermates served as controls. CR reduced body weight in both DS/obese and DS/lean rats, as well as attenuated the development of hypertension in DS/obese rats without affecting blood pressure in DS/lean rats. CR also reduced body fat content, ameliorated left ventricular hypertrophy, fibrosis, and diastolic dysfunction, and attenuated cardiac oxidative stress and inflammation in DS/obese rats. In addition, it increased serum adiponectin concentration, as well as downregulated the expression of angiotensin-converting enzyme and angiotensin II type 1A receptor genes in the heart of DS/obese rats. Our results thus show that CR attenuated obesity and hypertension, as well as left ventricular remodeling and diastolic dysfunction in DS/obese rats, with these latter effects being associated with reduced cardiac oxidative stress and inflammation.

Neuroadrenergic dysfunction in obesity: an overview of the effects of weight loss

PURPOSE OF REVIEW

The prevalence of obesity is rising to epidemic proportions worldwide, and in tandem so is that of type 2 diabetes. Neuroadrenergic abnormalities, comprising increased resting sympathetic nervous system activity and blunted sympathetic neural responsiveness are recognized features of metabolic syndrome obesity, which contribute importantly to both the pathophysiology and adverse clinical prognosis of this high-risk population. Weight loss is recommended as first-line treatment for obesity. This review examines the effects of nonpharmacological weight loss on sympathetic nervous system function under basal and stimulated conditions.

RECENT FINDINGS

Human weight loss trials show that even moderate weight reduction is accompanied by significant attenuation in resting whole-body norepinephrine spillover rate and muscle sympathetic nerve activity, an improvement in cardiac autonomic modulation, and a reversal of blunted sympathetic responsiveness at both peripheral and central nervous system levels. Recent findings underscore the relevance of insulin resistance in mediating blunted sympathetic responsiveness to endogenous hyperinsulinemia induced by glucose ingestion. Impaired insulin transport across the blood-brain barrier may be one mechanism mediating these effects. Weight loss reverses blunted sympathetic responsiveness to glucose, which has implications for postprandial energy expenditure and body weight homeostasis.

SUMMARY

The autonomic dysfunction of obesity is reversible with weight loss, highlighting the importance of lifestyle intervention as a key therapeutic modality.

Associations between being overweight, variability in heart rate, and well-being in the young men

Abnormalities of the autonomic nervous system have been repeatedly shown in hypertension. We studied the associations between being overweight, blood pressure, cardiac vagal tone as measured by variability in heart rate, and well-being in a large cohort of young men. We hypothesised an inverse correlation between body mass index and the variability in heart rate. Further, we assessed systolic and diastolic blood pressure as traditional indicators of cardiovascular risk. Exclusion criteria were the use of drugs or pharmaceuticals. The following data from 786 men with a mean age of 19.4 years (standard deviation = 1.4, with a range from 16 to 24 years) were analysed in a cross-sectional study: body mass index, sleep duration, sporting activities, psychological well-being, blood pressure, heart rate, and variability in heart rate. Despite the young age of the men in this study, increased values for the body mass index were already associated with a shift in sympathovagal balance trending towards sympathetic dominance. There was also a significant positive correlation between body mass index and systolic and diastolic blood pressure. A multiple stepwise regression analysis showed that significant factors, which were associated with variability in heart rate, were body mass index and sporting activities. In addition, sporting activity and sleep duration had a significant positive impact on psychological well-being. Even in young men, being overweight is associated with increased cardiovascular risk, especially an increased sympathetic and/or lowered cardiovascular tone and increased blood pressure. Our study gives additional motivation for the early prevention and treatment of obesity in childhood and adolescence.

Aging and dietary restriction effects on ubiquitination, sumoylation, and the proteasome in the heart

Dietary restriction (DR), in the absence of malnutrition, is the only intervention known to reliably increase average and maximal lifespan in a variety of organisms including mammals. Because the effects of DR on the heart are poorly understood, in the present study we examined the effects of DR on the ubiquitin-proteasome pathway (UPP) in the heart. In these studies we observed that DR significantly reduced age-related impairments in proteasome-mediated protein degradation, and reduced age-related increases in ubiquitinated, oxidized, and sumoylated protein in the heart. Interestingly, DR did not significantly increase the expression of 20S proteasome subunits or the proteasome maturation factor (POMP-1). These data demonstrate for the first time the effects of aging and DR on proteasome biogenesis and sumoylation in the heart. Cumulatively, our data indicate that DR has many beneficial effects towards the UPP in the heart, and suggests that a preservation of the UPP may be a potential mechanism by which DR mediates beneficial effects on the cardiovascular system.

Alternate-day fasting and chronic disease prevention: a review of human and animal trials

Calorie restriction (CR) and alternate-day fasting (ADF) represent 2 different forms of dietary restriction. Although the effects of CR on chronic disease prevention were reviewed previously, the effects of ADF on chronic disease risk have yet to be summarized. Accordingly, we review here animal and human evidence concerning ADF and the risk of certain chronic diseases, such as type 2 diabetes, cardiovascular disease, and cancer. We also compare the magnitude of risk reduction resulting from ADF with that resulting from CR. In terms of diabetes risk, animal studies of ADF find lower diabetes incidence and lower fasting glucose and insulin concentrations, effects that are comparable to those of CR. Human trials to date have reported greater insulin-mediated glucose uptake but no effect on fasting glucose or insulin concentrations. In terms of cardiovascular disease risk, animal ADF data show lower total cholesterol and triacylglycerol concentrations, a lower heart rate, improved cardiac response to myocardial infarction, and lower blood pressure. The limited human evidence suggests higher HDL-cholesterol concentrations and lower triacylglycerol concentrations but no effect on blood pressure. In terms of cancer risk, there is no human evidence to date, yet animal studies found decreases in lymphoma incidence, longer survival after tumor inoculation, and lower rates of proliferation of several cell types. The findings in animals suggest that ADF may effectively modulate several risk factors, thereby preventing chronic disease, and that ADF may modulate disease risk to an extent similar to that of CR. More research is required to establish definitively the consequences of ADF.

ACE inhibitors and statins acutely improve endothelial dysfunction of human coronary arterioles

Long-term treatment with angiotensin-converting enzyme (ACE) inhibitors as well as angiotensin II type 1 (AT1) receptor antagonists and statins reduces cardiovascular mortality in patients with coronary artery disease as well as chronic heart failure. Little is known about the acute effects of these compounds on vascular reactivity of coronary resistance vessels. Coronary arterioles were obtained from patients undergoing coronary bypass operation (atherosclerosis group) or valve replacement (control group). Responses to endothelium-dependent agonists (histamine, serotonin, and acetylcholine) as well as to the endothelium-independent agonist sodium nitroprusside (SNP) were investigated under baseline conditions and after incubation (15 min) with lisinopril (ACE inhibitor), candesartan (AT1 receptor antagonist), or fluvastatin. In atherosclerotic vessels, vasorelaxation was significantly reduced to all endothelium-dependent agonists but not, however, to SNP (77 ± 8, –24 ± 16, –46 ± 24, and 98 ± 8% relaxation for histamine, serotonin, acetylcholine, and SNP, respectively). Lisinopril and fluvastatin but not candesartan significantly improved the responses to the endothelium-dependent agonists (lisinopril: 94 ± 4, 17 ± 22, and –20 ± 13%; fluvastatin: 96 ± 8, 23 ± 21, and –25 ± 18% relaxation for histamine, serotonin, and acetylcholine, repectively). The effect of lisinopril was prevented by pretreatment with a bradykinin antagonist (HOE-130) and dichloroisocoumarine, an inhibitor of kinine-forming enzymes. Pretreatment with a nitric oxide (NO) synthase inhibitor abolished the improvement of endothelial function by lisinopril and fluvastatin. Vascular reactivity in the control group was not influenced by any of the pharmacological interventions. The data demonstrate that in atherosclerosis, endothelium-dependent relaxation of coronary resistance arteries is severely compromised. The impairment can acutely be reversed by ACE inhibitors and statins via increasing the availability of NO.

Hypothesis: shifting the equilibrium from activity to food leads to autonomic unbalance and the metabolic syndrome

“The stability of the internal environment is the condition that life should be free and independent… So, far from the higher animal being indifferent to the external world, it is on the contrary in a precise and informed relation with it, in such a way that its equilibrium results from a continuous and delicate compensation, established as by the most sensitive of balances.”

Claude Bernard (1865)

Central nervous determination of food storage—a daily switch from conservation to expenditure: implications for the metabolic syndrome

Here, we present a neuroendocrine concept to review the circularly interacting energy homeostasis system between brain and body. Body-brain interaction is circular because the brain immediately integrates an input to an output, and because part of this response may be that the brain modulates the sensitivity of this perception. First, we describe how the brain senses the body through neurons and blood-borne factors. Direct neuronal connections report the state of various organs. In addition, humoral factors are perceived by the blood-brain barrier and circumventricular organs. We describe how circulating energy carriers are sensed and what signals reach the brain during food intake, exercise and an immune response. We describe that the brain regulates the homeostatic process at two fundamentally different levels during the active and inactive states. The unbalanced output of the brain in the metabolic syndrome is discussed in relation with such circadian rhythms and with regional activity of the autonomic nervous system. In line with the above, we suggest a new approach for the diagnosis and therapy of the metabolic syndrome.

Emerging concepts in the pathophysiology and treatment of obesity-associated hypertension

The dramatic increase in the prevalence of obesity is a global phenomenon associated with increased risk of the development of cardiovascular and renal disease. Changes in renal structure and function that occur early in the development of obesity may lead to urine outflow obstruction and increased intrarenal pressure, mechanisms sufficient to shift the pressure-natriuresis relation to higher blood pressure levels. Another important alteration that may lead to hypertension with obesity is the increase in sympathetic nervous system activity. Several studies point to higher leptin levels associated with hypertension in humans, and animal data now convincingly suggest that leptin has direct central effects that increase sympathetic outflow to the kidneys, associated with increases in blood pressure. Although understanding of the pathophysiology of obesity-associated hypertension has made substantial progress during the past years, treatment of obese hypertensives remains largely empirical and clearly deserves to be addressed in larger randomized, controlled trials.