The Role of Sympatho-Inhibition in Combination Treatment of Obesity-Related Hypertension

Caloric restriction improves inflammation in different tissues of the Wistar rats with obesity and 2K1C renovascular hypertension

Renovascular hypertension (RHV) is the cause of high blood pressure due to left renal ischemia, and obesity and hypertension cause an inflammatory response. This work analyzed the inflammatory and tissue repair profile in renal, hepatic, and cardiac tissues in an animal model of RVH associated with a high-fat diet and caloric restriction. The expressions of RORγ-t, IL-17, T-bet, and TNF-α decreased and IFN-γ increased in the right kidney. In relation to the left kidney, caloric restriction decreased the expression of IFN-γ. In the liver, caloric restriction decreased RORγ-t, IL-17, and T-bet. Hypertension associated with obesity decreased the expression of IFN-γ, while caloric restriction increased. In the right kidney, hypertension and obesity, associated or not with caloric restriction, increased the area of collagen fibers. In the heart and liver, caloric restriction reduced the area of collagen fibers. Caloric restriction increased vascular endothelial growth factor, reduced levels of growth transformation factor-β1 (TGF-β), and increased collagen I in the left kidney. Hypertension/obesity, submitted or not having caloric restriction, increased TGF-β in liver. The results suggest that caloric restriction has beneficial effects in lowering blood pressure and regulating tissue proinflammatory cytokines. However, there was no change in the structure and composition of tissue repair markers.

Manifestations of Liver Impairment and the Effects of MH-76, a Non-Quinazoline α1-Adrenoceptor Antagonist, and Prazosin on Liver Tissue in Fructose-Induced Metabolic Syndrome

Excessive fructose consumption may lead to metabolic syndrome, metabolic dysfunction-associated fatty liver disease (MAFLD) and hypertension. α1-adrenoceptors antagonists are antihypertensive agents that exert mild beneficial effects on the metabolic profile in hypertensive patients. However, they are no longer used as a first-line therapy for hypertension based on Antihypertensive and Lipid-Lowering Treatment to Prevent Heart Attack Trial (ALLHAT) outcomes. Later studies have shown that quinazoline-based α1-adrenolytics (prazosin, doxazosin) induce apoptosis; however, this effect was independent of α1-adrenoceptor blockade and was associated with the presence of quinazoline moiety. Recent studies showed that α1-adrenoceptors antagonists may reduce mortality in COVID-19 patients due to anti-inflammatory properties. MH-76 (1-[3-(2,6-dimethylphenoxy)propyl]-4-(2-methoxyphenyl)piperazine hydrochloride)) is a non-quinazoline α1-adrenoceptor antagonist which, in fructose-fed rats, exerted anti-inflammatory, antihypertensive properties and reduced insulin resistance and visceral adiposity. In this study, we aimed to evaluate the effect of fructose consumption and treatment with α1-adrenoceptor antagonists of different classes (MH-76 and prazosin) on liver tissue of fructose-fed rats. Livers were collected from four groups (Control, Fructose, Fructose + MH-76 and Fructose + Prazosin) and subjected to biochemical and histopathological studies. Both α1-adrenolytics reduced macrovesicular steatosis and triglycerides content of liver tissue and improved its antioxidant capacity. Treatment with MH-76, contrary to prazosin, reduced leucocytes infiltration as well as decreased elevated IL-6 and leptin concentrations. Moreover, the MH-76 hepatotoxicity in hepatoma HepG2 cells was less than that of prazosin. The use of α1-adrenolytics with anti-inflammatory properties may be an interesting option for treatment of hypertension with metabolic complications.

Keeping obesity status is a risk factor of hypertension onset: evidence from a community-based longitudinal cohort study in North China

Objective

The purpose of our study was to investigate the association of obesity status change with hypertension onset based on a community-based longitudinal cohort study in North China.

Methods

This longitudinal study included 3,581 individuals free of hypertension at baseline in the first survey (2011-2012). All participants were followed up (2018-2019). According to the criteria, a total of 2,618 individuals were collected for analysis. We used adjusted Cox regression models and Kaplan-Meier survival analysis to estimate the association between obesity status change and hypertension onset. Additionally, we applied the forest plot to visualize the subgroup analysis including age, gender, and the differences in some variables between baseline and follow-up. Finally, we conducted a sensitivity analysis to examine the stability of our results.

Results

Over nearly 7 years of follow-up, a total of 811 (31%) developed hypertension. The new hypertension incidence was mostly observed in those who were obese all the time (P for trend < 0.01). In the fully adjusted Cox regression model, being obese all the time increased the risk of hypertension by 30.10% [HR 4.01 (95% CI 2.20-7.32)]. The Kaplan-Meier survival analysis revealed the change in obesity status as an important feature to predict the occurrence of hypertension. Sensitivity analysis shows a consistent trend between the change in obesity status and hypertension onset in all populations. Subgroup analysis showed that age above 60 years was an important risk factor for hypertension onset, that men were more likely than women to develop hypertension, and that weight control was beneficial in avoiding future hypertension in women. There were statistically significant differences in ΔBMI, ΔSBP, ΔDBP, and ΔbaPWV between the four groups, and all variables, except baPWV changes, increased the risk of future hypertension.

Conclusion

Our study shows that obese status was notably associated with a significant risk of hypertension onset among the Chinese community-based cohort.

Metabolic associated fatty liver disease is a disease related to sympathetic nervous system activation

Strong evidence from animal and human studies shows that sympathetic nervous system (SNS) activation is a key factor in the development of metabolic associated fatty liver disease (MAFLD). Activation of the sympathetic nervous system plays an important role in the pathogenesis of obesity, metabolic syndrome, diabetes, hypertension, and MAFLD. When genetically susceptible subjects are exposed to a variety of epigenetic changes, their liver damage may develop into MAFLD. Thus, the pathogenesis of MAFLD is complex, involving the complex interaction of insulin resistance, abnormal hormone secretion, obesity, diet, genetic factors, immune activation, gut microbiota, and other factors. In these processes, the role of sympathetic nerves cannot be underestimated. Notably, SNS has been proposed as a therapeutic target for MAFLD by inhibiting sympathetic nerves. It is worthy of further discussion and research.

Preserved β-adrenergic-mediated vasodilation in skeletal muscle of young adults with obesity despite shifts in cyclooxygenase and nitric oxide synthase

Central adiposity is associated with greater sympathetic support of blood pressure. β-adrenergic receptors (β-AR) buffer sympathetically mediated vasoconstriction and β-AR-mediated vasodilation is attenuated in preclinical models of obesity. With this information, we hypothesized β-AR vasodilation would be lower in obese compared with normal weight adults. Because β-AR vasodilation in normal weight adults is limited by cyclooxygenase (COX) restraint of nitric oxide synthase (NOS), we further explored the contributions of COX and NOS to β-AR vasodilation in this cohort. Forearm blood flow (FBF, Doppler ultrasound) and mean arterial blood pressure (MAP, brachial arterial catheter) were measured and forearm vascular conductance (FVC) was calculated (FVC = FBF/MAP). The rise in FVC from baseline (ΔFVC) was quantified during graded brachial artery infusion of isoproterenol (Iso, 1-12 ng/100 g/min) in normal weight (n = 36) and adults with obesity (n = 22) (18-40 yr old). In a subset of participants, Iso-mediated vasodilation was examined before and during inhibition of NOS [NG-monomethyl-l-arginine (l-NMMA)], COX (ketorolac), and NOS + COX (l-NMMA + ketorolac). Iso-mediated increases in FVC did not differ between groups (P = 0.57). l-NMMA attenuated Iso-mediated ΔFVC in normal weight (P = 0.03) but not adults with obesity (P = 0.27). In normal weight adults, ketorolac increased Iso-mediated ΔFVC (P < 0.01) and this response was lost with concurrent l-NMMA (P = 0.67). In contrast, neither ketorolac (P = 0.81) nor ketorolac + l-NMMA (P = 0.40) altered Iso-mediated ΔFVC in adults with obesity. Despite shifts in COX and NOS, β-AR vasodilation is preserved in young adults with obesity. These data highlight the presence of a compensatory shift in microvascular control mechanisms in younger humans with obesity.NEW & NOTEWORTHY We examined β-adrenergic receptor-mediated vasodilation in skeletal muscle of humans with obesity and normal weight. Results show that despite shifts in the contribution of cyclooxygenase and nitric oxide synthase, β-adrenergic-mediated vasodilation is relatively preserved in young, otherwise healthy adults with obesity. These data highlight the presence of subclinical changes in microvascular control mechanisms early in the obesity process and suggest duration of obesity and/or the addition of primary aging may be necessary for overt dysfunction.

Female Gender Is Associated with Higher Susceptibility of Weight Induced Arterial Stiffening and Rise in Blood Pressure

Arterial stiffness is an important predictor of cardiovascular events, independent of traditional risk factors. Stiffening of arteries, though an adaptive process to hemodynamic load, results in substantial increase in the pulsatile hemodynamic forces that detrimentally affects the microcirculation perfusing the vital organs such as the brain, heart and kidneys. Studies have proposed that arterial stiffness precedes and may contribute to the development of hypertension in individuals with obesity. Our study sought to determine the gender-based effects on arterial stiffening in obesity which may predispose to the development of hypertension. We found female sex is associated with higher susceptibility of weight-related arterial stiffening and rise in blood pressure in obesity. Women had significantly higher carotid-femoral pulse wave velocity (CF-PWV) with higher body mass index (BMI) status (normal: 7.9 ± 2 m/s; overweight: 9.1 ± 2 m/s; obese: 9 ± 2 m/s, p < 0.001), whereas it was similar in males across all BMI categories. The linear association between arterial stiffness and BMI following adjustment for age and brachial systolic and diastolic blood pressure (BP), remained significant in females (β = 0.06; 95% CI 0.01 to 0.1; p < 0.05) but not in males (β = 0.04; 95% CI -0.01 to 0.1; p > 0.05). The mean CF-PWV values increased by 0.1 m/s for every 1 kg/m² increase in BMI in the female subjects in the age adjusted linear model, while such effect was not seen in the male subjects. In line with arterial stiffening, the overweight and obese females demonstrated significantly higher systolic brachial BP. (BP difference: ΔBP 9-11 mmHg, p < 0.01) and central systolic pressure (ΔBP 8-10 mmHg, p < 0.05) compared to their lean counterparts, unlike the male subjects. Our results suggest that female gender is associated with higher susceptibility of weight-related arterial stiffening and rise in blood pressure.

Metabolic Dysfunction-Associated Fatty Liver Disease (MAFLD)-A Condition Associated with Heightened Sympathetic Activation

Metabolic dysfunction-associated fatty liver disease (MAFLD) is the most common liver disease affecting a quarter of the global population and is often associated with adverse health outcomes. The increasing prevalence of MAFLD occurs in parallel to that of metabolic syndrome (MetS), which in fact plays a major role in driving the perturbations of cardiometabolic homeostasis. However, the mechanisms underpinning the pathogenesis of MAFLD are incompletely understood. Compelling evidence from animal and human studies suggest that heightened activation of the sympathetic nervous system is a key contributor to the development of MAFLD. Indeed, common treatment strategies for metabolic diseases such as diet and exercise to induce weight loss have been shown to exert their beneficial effects at least in part through the associated sympathetic inhibition. Furthermore, pharmacological and device-based approaches to reduce sympathetic activation have been demonstrated to improve the metabolic alterations frequently present in patients with obesity, MetSand diabetes. Currently available evidence, while still limited, suggests that sympathetic activation is of specific relevance in the pathogenesis of MAFLD and consequentially may offer an attractive therapeutic target to attenuate the adverse outcomes associated with MAFLD.

Arterial Stiffness Predicts General Anesthesia-Induced Vasopressor-Resistant Hypotension in Patients Taking Angiotensin-Converting Enzyme Inhibitors

OBJECTIVES

Patients chronically treated with angiotensin-converting enzyme inhibitors (ACEIs) may develop hypotension after induction of general anesthesia. A fraction of these patients are resistant to therapeutic doses of vasopressors, which poses serious concerns for hemodynamic management. The authors hypothesized that the patients who develop refractory hypotension, compared with those who do not, show lower central arterial stiffness due to the profound effect of ACEIs.

DESIGN

Prospective observational study.

SETTING

Single tertiary center.

INTERVENTIONS

Fifty surgical patients chronically treated with ACEIs were enrolled. Prior to surgery, all the patients had central arterial stiffness assessment measured by carotid-femoral pulse-wave velocity. Patients were categorized into 2 groups according to the systolic blood pressure response during the first 10 minutes after induction of general anesthesia: a vasopressor-resistant hypotension group requiring more than 200 µg phenylephrine, or a control group requiring no more than 200 µg of phenylephrine to maintain systolic blood pressure above 90 mmHg during the study period.

MEASUREMENTS AND MAIN RESULTS

Carotid-femoral pulse-wave velocity was significantly lower in the vasopressor-resistant hypotension group compared to the control group (7.6 [7.2-8.3] m/s v 9.9 [8.7-12.0] m/s, p = 0.001 [Hodges-Lehman median difference 2.2, 95% confidence interval = 1.1-4.4]).

CONCLUSION

These findings suggested that preoperative measurement of carotid-femoral pulse-wave velocity in patients chronically treated with ACEIs could help identify patients at increased risk of developing hypotension refractory to vasopressors after induction of general anesthesia.

HuoXue QianYang QuTan Recipe attenuates left ventricular hypertrophy in obese hypertensive rats by improving mitochondrial function through SIRT1/PGC-1α deacetylation pathway

Mitochondrial dysfunction plays a vital role in the progression of left ventricular hypertrophy (LVH). Previous studies have confirmed that the disorder of SIRT1/PGC-1α deacetylation pathway aggravated mitochondrial dysfunction. HuoXue QianYang QuTan Recipe (HQQR) is a commonly used prescription that has shown therapeutic effects on obesity hypertension and its complications. However, the potential mechanisms are still unclear. In the present study, obesity hypertension (OBH) was established in rats and we investigated the efficacy and mechanisms of HQQR on LVH. Rats were divided into the five groups: (1) WKY-ND group, (2) SHR-ND group, (3) OBH-HF group, (4) OBH-HF/V group and (5) OBH-HF/H group. We evaluated body weight, Lee index and blood pressure (BP) before and every 2 weeks after treatment. After 10 weeks of treatment, we mainly detected glycolipid metabolic index, the severity of LVH, mitochondrial function along with SIRT1/PGC-1α deacetylation pathway. Our results showed that HQQR significantly lowered body weight, Lee index, BP and improved the disorder of glycolipid metabolism in OBH rats. Importantly, we uncovered HQQR could alleviate mitochondrial dysfunction in OBH rats by regulating SIRT1/PGC-1α deacetylation pathway. These changes could be associated with the inhibition of LVH.

Cardiac β-adrenergic responsiveness of obese Zucker rats: The role of AMPK

NEW FINDINGS

What is the central question of the study? Is the reduced signalling of AMP-activated protein kinase (AMPK), a key regulator of energy homeostasis in the heart, responsible for the reduced β-adrenergic responsiveness of the heart in obesity? What is the main finding and its importance? Inhibition of AMPK in isolated hearts prevented the reduced cardiac β-adrenergic responsiveness of obese rats, which was accompanied by reduced phosphorylation of AMPK, a proxy of AMPK activity. This suggests a direct functional link between β-adrenergic responsiveness and AMPK signalling in the heart, and it suggests that AMPK might be an important target to restore the β-adrenergic responsiveness in the heart in obesity.

ABSTRACT

The obesity epidemic impacts heavily on cardiovascular health, in part owing to changes in cardiac metabolism. AMP-activated protein kinase (AMPK) is a key regulator of energy homeostasis in the heart and is regulated by β-adrenoceptors (β-ARs) in normal conditions. In obesity, chronic sympathetic overactivation leads to impaired cardiac β-AR responsiveness, although it is unclear whether AMPK signalling, downstream of β-ARs, contributes to this dysfunction. Therefore, we aimed to determine whether reduced AMPK signalling is responsible for the reduced β-AR responsiveness in obesity. In isolated hearts of lean and obese Zucker rats, we tested β-AR responsiveness to the β₁ -AR agonist isoprenaline (ISO, 1 × 10^-10 to 5 × 10^-8  m) in the absence and presence of the AMPK inhibitor, compound C (CC, 10 μm). The β₁ -AR expression and AMPK phosphorylation were assessed by Western blot. β-Adrenergic responsiveness was reduced in the hearts of obese rats (logEC₅₀ of ISO-developed pressure dose-response curves: lean -8.53 ± 0.13 × 10^x  m versus obese -8.35 ± 0.10 × 10^x  m ; P < 0.05 lean versus obese, n = 6 per group). This difference was not apparent after AMPK inhibition (logEC₅₀ of ISO-developed pressure curves: lean CC -8.19 ± 0.12 × 10^x  m versus obese CC 8.17 ± 0.13 × 10^x  m, P < 0.05, n = 6 per group). β₁ -Adrenergic receptor expression and AMPK phosphorylation were reduced in hearts of obese rats (AMPK at Thr¹⁷² : lean 1.73 ± 0.17 a.u. versus lean CC 0.81 ± 0.13 a.u., and obese 1.18 ± 0.09 a.u. versus obese CC 0.81 ± 0.16 a.u., P < 0.05, n = 6 per group). Thus, a direct functional link between β-adrenergic responsiveness and AMPK signalling in the heart exists, and AMPK might be an important target to restore the reduced cardiac β-adrenergic responsiveness in obesity.

Effects of exercise intensity and cardiorespiratory fitness on the acute response of arterial stiffness to exercise in older adults

PURPOSE

Increased arterial stiffness is observed with ageing and in individuals with low cardiorespiratory fitness ([Formula: see text]O_2peak), and associated with cardiovascular risk. Following an exercise bout, transient arterial stiffness reductions offer short-term benefit, but may depend on exercise intensity. This study assessed the effects of exercise intensity on post-exercise arterial stiffness in older adults with varying fitness levels.

METHODS

Fifty-one older adults (72 ± 5 years) were stratified into fitness tertiles ([Formula: see text]O_2peak: low-, 22.3 ± 3.1; mid-, 27.5 ± 2.4 and high-fit 36.3 ± 6.5 mL kg^-1 min^-1). In a randomised order, participants underwent control (no-exercise), moderate-intensity continuous exercise (40% of peak power output; PPO), and higher-intensity interval exercise (70% of PPO) protocols. Pulse wave velocity (PWV), augmentation index (AIx75) and reflection magnitude (RM) were assessed at rest and during 90 min of recovery following each protocol.

RESULTS

After control, delta PWV increased over time (P < 0.001) and delta RM was unchanged. After higher-intensity interval exercise, delta PWV (P < 0.001) and delta RM (P < 0.001) were lower to control in all fitness groups. After moderate-intensity continuous exercise, delta PWV was not different from control in low-fit adults (P = 0.057), but was lower in the mid- and higher-fit older adults. Post-exercise AIx75 was higher to control in all fitness groups (P = 0.001).

CONCLUSIONS

In older adults, PWV increases during seated rest and this response is attenuated after higher-intensity interval exercise, regardless of fitness level. This attenuation was also observed after moderate-intensity continuous exercise in adults with higher, but not lower fitness levels. Submaximal exercise reveals differences in the arterial stiffness responses between older adults with higher and lower cardiorespiratory fitness.