Role of sympathetic nervous system and neuropeptides in obesity hypertension

Hypertension prevalence in Iran's elderly according to new criteria: the Tehran Geriatric Eye Study

Purpose

To determine the prevalence of hypertension in a population above 60 years of age and its relationship with demographic and anthropometric factors.

Methods

A cross-sectional population-based study was conducted in 2019. Using a multistage random cluster sampling, 160 clusters were selected from 22 districts of Tehran. All participants were interviewed to collect demographic, anthropometric, and socioeconomic information. Then, systolic (SBP) and diastolic (DBP) blood pressures were measured under standard conditions twice, 10 min apart. A third measurement was performed if the two measurements showed a difference of ≥ 10 mmHg in SBP or ≥ 5 mmHg in DBP. Hypertension was defined as a SBP > 130 mmHg or a DBP > 80 mmHg (new criteria), being a known case of hypertension, or use of blood pressure lowering medications.

Results

Of 3791 invitees, 3310 participated in the study (87.3%). The mean age of the participants was 68.25 ± 6.54 years (60-97 years). The prevalence of hypertension was 81.08% (95% CI: 79.57-82.59) in the whole sample; 82.96% (95% CI: 81.02-84.91) in females, and 79.15% (95% CI: 76.6 -81.69) in males. The prevalence of hypertension ranged from 75.47% (95% CI: 72.65-78.29) in the age group 60-64 years to 88.40% (95% CI: 83.71-93.08) in the age group ≥ 80 years. The prevalence of hypertension unawareness was 32.84% (95% CI: 30.82-34.86). The highest and lowest prevalence of hypertension was seen in illiterate subjects (89.41%) and those with a university education (77.14%), respectively. According to the multiple logistic regression analysis, older age, lower education level, obesity and overweight, neck circumference, and diabetes were significantly associated with the prevalence of hypertension.

Conclusion

A significant percentage of Iranian elderly have hypertension and one of every 3 affected individuals is unaware of their disease. Considering the population aging in Iran, urgent and special attention should be paid to the elderly population. Caring for the elderly, informing families, and using non-traditional screening methods are recommended by families at the first level and policymakers at the macro level.

The Magnitude of Hypertension and Its Contributing Factors Among Patients Receiving Antiretroviral Therapy in Public Hospitals in Harar City, Eastern Ethiopia: A Cross-Sectional Study

Background

Although people living with HIV (PLHIV) are surviving longer due to the development of highly active antiretroviral therapy (HAART), hypertension continues to be a significant obstacle for human immunodeficiency virus (HIV) positive patients.

Purpose

This study aims to determine the prevalence of hypertension and its contributing factors among patients receiving HAART in public hospitals in Harar City, Eastern Ethiopia.

Patients and Methods

A hospital-based cross-sectional study was conducted among adult PLHIV who receive HAART in public hospitals in Harar City, Eastern Ethiopia, from 20 March to 14 April 2023. A simple random sampling technique was employed to select a total of 406 clients (382 participated in the study). Data were collected through patient interview and chart review using a questionnaire. The binary logistic regression was used for data analysis. The association was declared statistically significant at a p-value less than 0.05.

Results

The magnitude/prevalence of hypertension was 23% (95% CI: 19.1, 27.5) in study settings from a total of 382 adults who participated in this study. Factors significantly associated with hypertension in a multivariable binary logistic regression model include residence (rural residence, AOR = 1.95, 95% CI: 1.04, 3.65); body mass index (obese, AOR = 4.35, 95% CI: 1.08, 16.77); cigarette smoking (past cigarette smoking, AOR = 4.7, 95% CI: 1.10, 21.8); and HAART regimen change (AOR = 0.44, 95% CI: 0.20, 0.97).

Conclusion

The prevalence of hypertension observed among adult PLHIV in the study settings was high. Adults from rural areas, with a history of past smoking cigarette, and obesity need close attention during their clinic visits for more health education to reduce risk factors. The changed HAART regimen was associated with a reduced risk of hypertension. Generally, hypertensive PLHIV need consideration for their double burden of communicable and non-communicable diseases during disease management and hospital guideline development.

Evaluation of Cardiovascular Response to Isometric Handgrip Exercise in Obese Individuals

Background The variability in hemodynamic responses to isometric handgrip exercise in people with different body mass indices (BMIs) is noteworthy due to the frequent incidence of hypertension, obesity, and related cardiovascular illnesses in India. This investigation may be necessary to anticipate and prevent excessive heart strain during static activities. Therefore, this study aimed to evaluate the impact of isometric handgrip exercise on cardiorespiratory responses in an Indian population with varying BMI levels. The objective was to compare the cardiovascular responses of obese and non-obese individuals to an isometric handgrip exercise test (heart rate, systolic blood pressure, diastolic blood pressure, rate pressure product, and mean arterial pressure). Methodology This study was conducted from April 2021 to October 2022. Measurements were obtained using a pedestal-style weighing scale with a maximum capacity of 120 kg and an accuracy of 100 g at the Department of Physiology, Indira Gandhi Institute of Medical Sciences, Patna. Sphygmomanometer was used for measuring blood pressure, and a stopwatch was used to time the duration of each prolonged isometric contraction performed by the participants using a handgrip dynamometer. Baseline measurements of heart rate, blood pressure, cardiac output, and heart rate variability were done during the final three minutes of the rest phase and once more throughout the 10-minute recovery period that followed the isometric handgrip exercise. Results The average heart rate increased during the isometric handgrip exercise in the obese group (13.02 ± 1.88 beats per minute). Systolic blood pressure increased by 16.40 ± 2.65 mmHg and 23.66 ± 3.14 mmHg in the obese group and the normal weight group, respectively. The diastolic blood pressure increased similarly in the overweight and normal weight groups, measuring 18.64 ± 3.63 mmHg and 12.14 ± 1.95 mmHg, respectively. Furthermore, the mean blood pressure increased by 20.45 ± 3.13 mmHg and 13.67 ± 1.64 mmHg, respectively, both in the normal and overweight groups. Conclusions Obese individuals had greater resting heart rates, systolic blood pressure, and diastolic blood pressure than non-obese individuals. Following an isometric handgrip workout, non-obese individuals reported greater increases in heart rate, systolic blood pressure, and diastolic blood pressure than obese individuals.

Prevalence, awareness, and control of hypertension and associated factors among Royal Thai Army personnel in Thailand from 2017 to 2021

Hypertension (HTN) is a potential risk factor for cardiovascular diseases. We aimed to determine the prevalence, awareness, and control of HTN among RTA personnel in Thailand. We conducted a series of cross-sectional studies from 2017 to 2021. HTN was defined by systolic blood pressure (BP) ≥ 140 mmHg or a diastolic BP ≥ 90 mmHg from a physical health examination, a history of HTN diagnosed by medical personnel, or taking antihypertensive medication. A total of 504,484 participants were included in the present study. The overall HTN prevalence was 29.4%. The prevalence of HTN among males was 30.5%, while it was 17.1% among females. Of the RTA personnel with HTN, 35.9% were aware of their condition. The overall control of HTN among RTA personnel with HTN was 15.8% in 2017 and 17.6% in 2021. Behavioral factors associated with HTN were current smoking, alcohol consumption, and sedentary behavior. A higher BMI was associated with higher HTN prevalence and HTN awareness but less likely to have controllable HTN. Male participants, younger individuals, current alcohol use, and sedentary behavior were associated with a lower prevalence of HTN awareness and controlled HTN. Current tobacco use was also associated with a lower prevalence of HTN awareness.

Sympathectomy Effects on Intra-Abdominal Organ Catecholamine Levels in a Streptozotocin-Induced Diabetic Rat Model

Diabetes mellitus (DM) is a metabolic disorder whose prevalence has continuously increased worldwide and is associated with dysfunction of the autonomic nervous system and, in particular, that of the sympathetic nervous system (SNS). The objective of this study was to analyze the interaction of DM and the SNS, building a model of sympathectomized diabetic rats to determine alterations in the content of CA (catecholamines) in different intra-abdominal organs. Sympathectomy was conducted with guanethidine (GNT). Additionally, DM was induced with STZ (Streptozotocin). Treatment with GNT decreased norepinephrine (NE) content in all analyzed tissues, with significant differences found in the paraganglia, liver, pancreas, duodenum, and heart compared to the control group. With respect to epinephrine (E), which was only found in the liver, pancreas, and heart, presenting significant differences (p < 0.05) in the heart, a decrease in its concentration was observed for all of the experimental groups with respect to the control. The decrease in dopamine (DA) content due to the GNT−STZ treatment was 30.1% in the heart with respect to the diabetic (STZ) group. The amount of CA in the adrenal medulla indicates the effect of sympathectomy on the GNT group where there was a significant reduction (p < 0.05) of DA. These findings suggest that the elimination of the sympathetic nervous system in diabetic organisms contributed to a decrease in blood glucose; likewise, an alteration in the levels of CA was observed in the different selected organs, possibly attributed to the severity, duration, and pathogenesis of the complications of acute and chronic DM.

Association of Obesity, Sarcopenia, and Sarcopenic Obesity With Hypertension in Adults: A Cross-Sectional Study From Ravansar, Iran During 2014-2017

BACKGROUND AND AIMS

Hypertension may lead to disability and death by increasing the risk of cardiovascular disease, kidney failure, and dementia. This study aimed to determine the association between obesity, sarcopenia and sarcopenic obesity, and hypertension in adults resident in Ravansar, a city in the west of Iran.

METHODS

This cross-sectional study was conducted on 4,021 subjects from the baseline data of the Ravansar Non-Communicable Disease (RaNCD) cohort study, in the west region of Iran, from October 2014 up to February 2017. Body composition was categorized into obese, sarcopenia, sarcopenic obese, and normal based on measurements of muscle strength, skeletal muscle mass, and waist circumference. Univariate and multiple logistic regression models were used to examine the relationships, using the STATA 15 software.

RESULTS

The mean age of the participant was 47.9 years (SD: 8.4), the body mass index (BMI) was 26.84 kg/m² (SD: 4.44), and the prevalence of hypertension was 15.12%. The prevalence of obesity, sarcopenia, and sarcopenic obesity were 24.37, 22.01, and 6.91%, respectively. Body composition groups had significant differences in age, total calorie intake, BMI, skeletal muscle mass, and muscle strength (P-value ≤ 0.001). In crude model, the obese (OR = 2.64; 95% CI: 2.11-3.30), sarcopenic (OR = 2.45; 95% CI: 1.94-3.08), and sarcopenic obese (OR = 3.83; 95% CI: 2.81-5.22) groups had a higher odds of hypertension. However, in adjusted models, only the obese group had a higher likelihood of hypertension (OR = 2.18; 95% CI: 1.70-2.80).

CONCLUSION

This study showed that obesity was associated with hypertension, whereas sarcopenia and sarcopenic obesity had no significant relationship with hypertension.

Assessing non-protein nitrogen sources in commercial dry dog foods

Protein is a macronutrient required by dogs for growth and maintenance metabolism. However, a portion of the crude protein listed on pet foods may actually arise from non-digestible organic nitrogen or potentially toxic inorganic non-protein nitrogen sources. Neither non-protein source is retained or used by the animal. However, these compounds may result in adverse effects such as methemoglobin formation and increased oxidative stress or potentially beneficial effects such as improved vascular distensibility and decreased inflammation. To analyze nitrogen retention and screen for non-protein nitrogen, four commercial, dry kibble dog foods and one laboratory-made diet were evaluated and then fed to beagles during two separate feeding trials. During the first trial, dogs were randomly assigned each diet (n = 4 dogs/diet) and fed chromium oxide-coated diets for 48 h, followed by total urine and marked fecal collection, as well as plasma collection for total nitrogen, nitrate, ammonia, and urea determination. The amount of nitrogen retained (93%–96%) did not differ among commercial diets. Protein total tract apparent digestibility (TTAD) ranged from 69% to 84%, with the high protein diets significantly higher than the laboratory-made and mid-ranged diets (1-way ANOVA: P < 0.05). The high protein diet also contained the highest concentration of nitrate with subsequent elevations in plasma nitrotyrosine levels (indicator of oxidative stress). During the second trial, eight dogs (n = 8) were fed the same diets for 6 d, after which echocardiography was completed with blood, urine, and feces collected. For health end-points, methemoblobin, plasma nitrotyrosine, and C-reactive protein (CRP; indicator of inflammation) levels were measured. Methemoglobin levels were significantly lower in the high protein diet (P > 0.05), possible due to the stimulation of methemoglobin reductase while nitrotyrosine was unchanged and CRP was undetectable. Furthermore, there was a positive relationship between crude protein, crude fat (simple linear regression: P = 0.02, r² > 0.6), price (P = 0.08, r² > 0.6), and caloric density (P = 0.11, r² > 0.6). There were no significant cardiovascular differences among any of the diets (P > 0.05). Ultimately, this study shows that in commercial diets, price does reflect protein content but that feeding dogs high protein diets for a long period of time may provide an excess in calories without a change in cardiovascular function or detectable increases in inflammation.

Nocturnal non-dipping on 24-h Ambulatory Blood Pressure Monitoring in children and adolescents with obesity is associated with higher total cholesterol levels

BACKGROUND

Few studies indicate the occurrence of abnormal nocturnal dipping of blood pressure (BP) in 35-50% of children and adolescents with obesity. The relation between that phenomenon and metabolic complications of obesity remains unclear. To evaluate the association between disorders of glucose and lipid metabolism, and nocturnal non-dipping in pediatric patients with obesity.

METHODS

In 207 children (53.14% girls, mean age 14 (range 2-17), mean BMI Z-SCORE 4.38, range 2.07-10.74) standard 24-h Ambulatory Blood Pressure Monitoring was performed. Normal dipping was defined as a ≥ 10% decline in BP during the night.

RESULTS

There were 106 (51.21%) cases of non-dippers. The mean 24-h nocturnal systolic BP (SBP) reduction (%) was 9.9 ± 5.5. The mean 24-h nocturnal diastolic BP (DBP) reduction (%) was 15.8 ± 8.5. There was a significant correlation between BMI Z-SCORE and mean day-time SBP (r = 0.14 P = .042). There are positive correlations between 24-h heart rate (beats/min) and BMI Z-SCORE (r = 0.15, P = .027), between fasting glucose and systolic BP Z-SCORE (r = 0.17, P = .03) and between mean diastolic BP and LDL cholesterol (r = 0.23, P = .004). Total cholesterol level was significantly higher in non-dippers (4.34 vs. 3.99 mmol/L, P = .034). There were no significant differences between non-dippers and dippers regarding fasting glucose (4.6 vs. 4.8 mmol/L), 120'post load glucose (5.7 vs. 5.9 mmol/L), insulin (19 vs. 20.2 µIU/mL), HOMA-IR (2.36 vs. 2.44), LDL cholesterol (2.64 vs. 2.51 mmol/L), HDL cholesterol (1.06 vs. 1.03 mmol/L) or triglycerides (1.36 vs. 1.34 mmol/L) levels.

CONCLUSION

Nocturnal non-dipping is frequent in pediatric patients with obesity. It is associated with higher total cholesterol levels.

Prevalence, risk factors, and management of uncontrolled hypertension among patients with diabetes: A hospital-based cross-sectional study

AIMS

This research examines the prevalence of uncontrolled hypertension and associated risk factors among patients with diabetes in Saudi Arabia.

METHODS

A hospital-based, cross-sectional study was used in patients with diabetes and hypertension attending outpatient diabetes clinics in King Khaled Hospital and Prince Sultan Center for Health Care in Al-Kharj, Riyadh. Patients' information, data on hypertension, type of treatment, and comorbidities were captured through electronic medical records. Uncontrolled hypertension was defined as blood pressure (BP) measurements greater than or equal to 140/90 mmHg. Antihypertensive medication use among these patients was analyzed. Multivariate analysis was performed to detect the associated factors of uncontrolled hypertension.

RESULTS

Of 1178 outpatients‬ with diabetes who were included in the study sample, uncontrolled hypertension presented in 846 (71.8%). Most patients were on two antihypertensive medications, and the most frequently used was calcium channel blockers, followed by angiotensin-converting enzyme inhibitors. Individuals most likely to have uncontrolled hypertension were those older than 65 years (OR 1.99, 95%CI: 1.059, 3.77), male (OR = 1.51, 95%CI: 1.031, 2.22), and obese (OR = 2.39, 95%CI: 1.63, 3.504), with two (OR = 3.894, 95% CI: 2.481, 6.114) or three or more comorbidities (OR = 4.020, 95% CI: 2.510, 6.439), and with polypharmacy (OR = 1.814, 95% CI: 1.238, 2.656).

CONCLUSION

The extent of uncontrolled hypertension among patients with diabetes in the study sample was found to be high. Age, sex, obesity, number of comorbidities, and polypharmacy are the most important correlates with increased risk of uncontrolled hypertension.

First-trimester pre-eclampsia biomarker profiles in Asian population: multicenter cohort study

OBJECTIVES

To (i) evaluate the applicability of the European-derived biomarker multiples of the median (MoM) formulae for risk assessment of preterm pre-eclampsia (PE) in seven Asian populations, spanning the east, southeast and south regions of the continent, (ii) perform quality-assurance (QA) assessment of the biomarker measurements and (iii) establish criteria for prospective ongoing QA assessment of biomarker measurements.

METHODS

This was a prospective, non-intervention, multicenter study in 4023 singleton pregnancies, at 11 to 13 + 6 weeks' gestation, in 11 recruiting centers in China, Hong Kong, India, Japan, Singapore, Taiwan and Thailand. Women were screened for preterm PE between December 2016 and June 2018 and gave written informed consent to participate in the study. Maternal and pregnancy characteristics were recorded and mean arterial pressure (MAP), mean uterine artery pulsatility index (UtA-PI) and maternal serum placental growth factor (PlGF) were measured in accordance with The Fetal Medicine Foundation (FMF) standardized measurement protocols. MAP, UtA-PI and PlGF were transformed into MoMs using the published FMF formulae, derived from a largely Caucasian population in Europe, which adjust for gestational age and covariates that affect directly the biomarker levels. Variations in biomarker MoM values and their dispersion (SD) and cumulative sum tests over time were evaluated in order to identify systematic deviations in biomarker measurements from the expected distributions.

RESULTS

In the total screened population, the median (95% CI) MoM values of MAP, UtA-PI and PlGF were 0.961 (0.956-0.965), 1.018 (0.996-1.030) and 0.891 (0.861-0.909), respectively. Women in this largely Asian cohort had approximately 4% and 11% lower MAP and PlGF MoM levels, respectively, compared with those expected from normal median formulae, based on a largely Caucasian population, whilst UtA-PI MoM values were similar. UtA-PI and PlGF MoMs were beyond the 0.4 to 2.5 MoM range (truncation limits) in 16 (0.4%) and 256 (6.4%) pregnancies, respectively. QA assessment tools indicated that women in all centers had consistently lower MAP MoM values than expected, but were within 10% of the expected value. UtA-PI MoM values were within 10% of the expected value at all sites except one. Most PlGF MoM values were systematically 10% lower than the expected value, except for those derived from a South Asian population, which were 37% higher.

CONCLUSIONS

Owing to the anthropometric differences in Asian compared with Caucasian women, significant differences in biomarker MoM values for PE screening, particularly MAP and PlGF MoMs, were noted in Asian populations compared with the expected values based on European-derived formulae. If reliable and consistent patient-specific risks for preterm PE are to be reported, adjustment for additional factors or development of Asian-specific formulae for the calculation of biomarker MoMs is required. We have also demonstrated the importance and need for regular quality assessment of biomarker values. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

Prevalence and associated factors of uncontrolled hypertension among hypertensive patients: a nation-wide survey in Thailand

Objectives

The objectives of the research were to determine the prevalence and factors associated of uncontrolled blood pressure among Thai hypertensive patients in a nationwide survey.

Results

A total of 65,667 patients with hypertension were included in this study. The greater proportion of participants, 40,834 (62.2%), were females. The average age of participants was 63.9 ± 11.1 years. Uncontrolled hypertension was detected among 16,122 patients (24.6%; 95% CI 24.2–24.9). Among males and females, uncontrolled hypertension was 25.6% (95% CI 25.1–26.2) and 23.9% (95% CI 23.5–24.3) respectively. Multivariate analysis showed that the uncontrolled hypertension was significantly associated with being male, age, regions, hospital levels, diabetes comorbidity, higher body mass index, low density lipoprotein cholesterol level and the number of antihypertensive medications.

Is Aberrant Reno-Renal Reflex Control of Blood Pressure a Contributor to Chronic Intermittent Hypoxia-Induced Hypertension?

Renal sensory nerves are important in the regulation of body fluid and electrolyte homeostasis, and blood pressure. Activation of renal mechanoreceptor afferents triggers a negative feedback reno-renal reflex that leads to the inhibition of sympathetic nervous outflow. Conversely, activation of renal chemoreceptor afferents elicits reflex sympathoexcitation. Dysregulation of reno-renal reflexes by suppression of the inhibitory reflex and/or activation of the excitatory reflex impairs blood pressure control, predisposing to hypertension. Obstructive sleep apnoea syndrome (OSAS) is causally related to hypertension. Renal denervation in patients with OSAS or in experimental models of chronic intermittent hypoxia (CIH), a cardinal feature of OSAS due to recurrent apnoeas (pauses in breathing), results in a decrease in circulating norepinephrine levels and attenuation of hypertension. The mechanism of the beneficial effect of renal denervation on blood pressure control in models of CIH and OSAS is not fully understood, since renal denervation interrupts renal afferent signaling to the brain and sympathetic efferent signals to the kidneys. Herein, we consider the currently proposed mechanisms involved in the development of hypertension in CIH disease models with a focus on oxidative and inflammatory mediators in the kidneys and their potential influence on renal afferent control of blood pressure, with wider consideration of the evidence available from a variety of hypertension models. We draw focus to the potential contribution of aberrant renal afferent signaling in the development, maintenance and progression of high blood pressure, which may have relevance to CIH-induced hypertension.

Hypertension in Obesity: Novel Insights

BACKGROUND

The relationship between obesity and hypertension has been established in both adults and children. The combination of obesity, hypertension and other cardiovascular risk factors significantly increases the likelihood of adverse cardiovascular effects and raises concerns about aggressive treatment strategies.

OBJECTIVE

Despite the impressive elements which indicate an important role for excessive weight gain in increasing blood pressure, not all obese patients are hypertensive. A subgroup of obese people may not develop hypertension. Furthermore, masked hypertension occurs more common among obese patients, and body fat distribution has a major role in the development of hypertension.

METHOD

We conducted a research of the relevant literature regarding obesity-induced hypertension and possible treatment strategies.

RESULTS

Successful weight loss is correlated with blood pressure reduction and requires a multidisciplinary approach that includes personalized dietary interventions combined with regular exercise and cognitive behavioral therapy.

CONCLUSION

Pharmacological therapy may be considered as part of a comprehensive obesity management strategy. More research and new treatment therapies are required in this field.

Moderate Physical Training Ameliorates Cardiovascular Dysfunction Induced by High Fat Diet After Cessation of Training in Adult Rats

We aimed to test whether moderate physical training can induce long-lasting protection against cardiovascular risk factors induced by high fat diet (HFD) intake, even after cessation of training. 90-days-old Wistar rats were submitted to a sedentary lifestyle or moderate physical training, three times a week, for 30 days. Following this, at 120 days-of age, sedentary and trained rats received a hypercaloric diet (HFD) or a commercial diet normal fat diet (NFD) for 30 days. Body weight (BW) and food intake were evaluated weekly. At 150 days-of age, hemodynamic measures (systolic, diastolic, mean blood pressure, pulse pressure, pulse interval and heart rate) were made via an indwelling femoral artery catheter. Beat-to-beat data were analyzed to calculate power spectra of systolic blood pressure (SBP) and pulse interval. After euthanasia, mesenteric fat pads were removed and weighted and total blood was stored for later analysis of lipid profile. Consumption of a HFD increased blood pressure (BP), pulse pressure, low frequency BP variability, BW gain, fat pad stores and induced dyslipidemia. Interestingly, prior physical training was able to partially protect against this rise in BP and body fat stores. Prior physical training did not totally protect against the effects of HFD consumption but previously trained animals did demonstrate resistance to the development of cardiometabolic alterations, which illustrate that the benefits of physical training may be partially maintained even after 30 days of detraining period.

Prevalence and associated factors of uncontrolled blood pressure among hypertensive patients in the rural communities in the central areas in Thailand: A cross-sectional study

Introduction

Hypertension is a common cardiovascular disease at present. Uncontrolled blood pressure leads to further complications including heart attack, stroke and chronic kidney disease. In Thailand, most of the information related to this issue is collected by hospitals or hospital-based organizations rather than at the community level. The objectives of this study were to determine the prevalence of uncontrolled hypertension and to assess the relationship between patient characteristics (socio-behavioral and clinical) and uncontrolled blood pressure among hypertensive patients in the rural communities in the central areas in Thailand.

Materials and methods

This was a cross-sectional study conducted in Na-Yao and Phra-Pleong rural communities of Thailand in 2018 using the total design method. In all, 406 individuals aged ≥18 years were interviewed using structured questionnaires related to demographic information, higher risk behavior, comorbidities and arthrometric measurement. Blood pressure was assessed for all participants. Uncontrolled hypertension was defined as BP ≥140/90 mmHg.

Results

The prevalence of uncontrolled hypertension was 54.4% (males: 59.8%; females: 52.4%). Uncontrolled blood pressure was associated with neck circumference more than 35.75 cm for males and 32.75 cm. for females (adjusted odds ratio; 1.66, 95% confidence interval; 1.03–2.68), sedentary behavior more than 5 hours a day (adjusted odds ratio; 2.03, 95% confidence interval; 1.28–3.23) and missed doctor appointments (adjusted odds ratio; 3.29, 95% confidence interval; 1.09–9.94).

Conclusion

Approximately one half of hypertensive patients in these rural communities had uncontrolled blood pressure. The Ministry of Public Health and health care providers should provide further strategies to prevent uncontrolled blood pressure’s complications.

Adipokine Profiling in Adult Women With Central Obesity and Hypertension

Central obesity and hypertension are common risk factors for the metabolic syndrome, cardiovascular and renal diseases. Studies have shown that it is more difficult to control blood pressure and prevent end-organ damage in obese individuals with hypertension compared to their non-obese counterparts, especially among women. Obese females have a 6 times higher risk of developing hypertension than non-obese females while obese males are at a 1.5 times higher risk of developing hypertension, compared to their non-obese counterparts. Indeed, the inter-relationship between obesity and hypertension is unclear. Adipokines have been proposed to play a mediating role in the relationship between obesity and hypertension and are involved in the pathogenesis of metabolic diseases. Therefore, this study sought to determine the role of adipokines (adiponectin, plasminogen activator inhibitor-1, leptin, and tumor necrosis factor-α) in hypertensive Hong Kong Chinese women with central obesity. A total of 387 women aged 58 ± 11 years who were examined with a 2 × 2 factorial design for central obesity (waist circumference ≥ 80 cm) and hypertension (blood pressure ≥ 140/90 mmHg), were recruited from a pool of 1,492 Hong Kong Chinese adults who were previously screened for metabolic syndrome. Subjects with hyperglycemia, hypertriglyceridemia, and dyslipidemia were excluded to eliminate confounding effects. Our findings revealed that hypertensive women with central obesity had a lower anti-inflammatory status (adiponectin) and a higher pro-inflammatory status (TNF-α) than obese alone or hypertensive alone women. Also, women with central obesity had higher circulatory PAI-1 and leptin concentrations than their non-obese counterparts. We conclude that obesity may shift toward a more pro-inflammatory state and may become more severe in the presence of hypertension or vice versa.

Associations of Blood Pressure with the Factors among Adults in Jilin Province: A Cross-Sectional Study Using Quantile Regression Analysis

Hypertension has become a major public health challenge. However, numerous research results reported in the literature focus primarily on risk factors of hypertension, little is known about how the whole continuum of blood pressure (BP) is associated with risk factors of hypertension. This study aims to reveal quantile-specific associations of BP with its risk factors. A cross-sectional survey based on a sample of 23,050 adults aged 18 to 79 years was conducted in Jilin Province in 2012, and some subjects were excluded due to missing values in BP or having BP control according to the purpose of this study. Quantile regression (QR) was employed to investigate the associations between systolic/diastolic blood pressure (SBP/DBP) and the risk factors. The SBP and DBP in males presented statistically higher than females (P < 0.001). High-salt diet for males manifested a slightly increasing positive association with higher SBP only for high quantiles (≥70), but with a higher DBP for middle part of the quantiles (30~75), compared with bland diet. High-salt diet, drinking and high-density lipoprotein cholesterol (HDL-C) were positively associated with BP measures in males. And the coefficient of total cholesterol (TC) in QR increased with BP in females who used to live in town.

Comparative Assessment of Some White Blood Cell and Platelet Parameters among Normotensive and Hypertensive Subjects in Port Harcourt, Nigeria

Background

Reports comparing the values of white blood cells (WBCs) and platelet parameters among normotensive, newly diagnosed hypertensive, and known hypertensive participants in Nigeria are relatively scarce. This study sought to compare these hematologic parameters of normotensive and hypertensive participants in the Southeastern Nigeria.

Materials and Methods

Fifty participants each of normotensive, newly diagnosed hypertensive, and known hypertensive and age- and sex-matched individuals were recruited into the study. Using an automated hematology analyzer, the following hematological parameters were determined in all participants: total WBC; neutrophil, lymphocyte and platelet counts; percentage value of neutrophil and lymphocytes; mean platelet volume (MPV); platelet distribution width; and total lymphocyte count.

Results

Significantly higher total WBCs and (absolute) neutrophil counts and lower percentage lymphocyte were observed among known hypertensive male participants, whereas percentage neutrophil was significantly higher among known hypertensive female participants. Platelet count and MPV were significantly higher in hypertensive male participants compared to their normotensive counterparts. MPV was found to be significantly lower in hypertensive female participants compared to normotensive females.

Conclusion

The present study reports significantly higher leukocytes, platelet counts, and MPV among hypertensive males and lower MPV among hypertensive females. Regular assessment of hematological parameters may perhaps be useful indicators of the prognosis of hypertension among the study population.

Obesity: A Perspective from Hypertension

The prevalence of obesity-related hypertension is high worldwide and has become a major health issue. The mechanisms by which obesity relates to hypertensive disease are still under intense research scrutiny, and include altered hemodynamics, impaired sodium homeostasis, renal dysfunction, autonomic nervous system imbalance, endocrine alterations, oxidative stress and inflammation, and vascular injury. Most of these contributing factors interact with each other at multiple levels. Thus, as a multifactorial and complex disease, obesity-related hypertension should be recognized as a distinctive form of hypertension, and specific considerations should apply in planning therapeutic approaches to treat obese individuals with high blood pressure.

The role of food intake regulating peptides in cardiovascular regulation

Obesity is a risk factor that worsens cardiovascular events leading to higher morbidity and mortality. However, the exact mechanisms of relation between obesity and cardiovascular events are unclear. Nevertheless, it has been demonstrated that pharmacological therapy for obesity has great potential to improve some cardiovascular problems. Therefore, it is important to determine the common mechanisms regulating both food intake and blood pressure. Several hormones produced by peripheral tissues work together with neuropeptides involved in the regulation of both food intake and blood pressure. Anorexigenic (food intake lowering) hormones such as leptin, glucagon-like peptide-1 and cholecystokinin cooperate with α-melanocyte-stimulating hormone, cocaine- and amphetamine-regulated peptide as well as prolactin-releasing peptide. Curiously their collective actions result in increased sympathetic activity, especially in the kidney, which could be one of the factors responsible for the blood pressure increases seen in obesity. On the other hand, orexigenic (food intake enhancing) peptides, especially ghrelin released from the stomach and acting in the brain, cooperates with orexins, neuropeptide Y, melanin-concentrating hormone and galanin, which leads to decreased sympathetic activity and blood pressure. This paradox should be intensively studied in the future. Moreover, it is important to know that the hypothalamus together with the brainstem seem to be major structures in the regulation of food intake and blood pressure. Thus, the above mentioned regions might be essential brain components in the transmission of peripheral signals to the central effects. In this short review, we summarize the current information on cardiovascular effects of food intake regulating peptides.

Obesity and hypertension

The imbalance between energy intake and expenditure is the main cause of excessive overweight and obesity. Technically, obesity is defined as the abnormal accumulation of ≥20% of body fat, over the individual's ideal body weight. The latter constitutes the maximal healthful value for an individual that is calculated based chiefly on the height, age, build and degree of muscular development. However, obesity is diagnosed by measuring the weight in relation to the height of an individual, thereby determining or calculating the body mass index. The National Institutes of Health have defined 30 kg/m² as the limit over which an individual is qualified as obese. Accordingly, the prevalence of obesity in on the increase in children and adults worldwide, despite World Health Organization warnings. The growth of obesity and the scale of associated health issues induce serious consequences for individuals and governmental health systems. Excessive overweight remains among the most neglected public health issues worldwide, while obesity is associated with increasing risks of disability, illness and death. Cardiovascular diseases, the leading cause of mortality worldwide, particularly hypertension and diabetes, are the main illnesses associated with obesity. Nevertheless, the mechanisms underlying obesity-associated hypertension or other associated metabolic diseases remains to be adequately investigated. In the present review, we addressed the association between obesity and cardiovascular disease, particularly the biological mechanisms linking obesity and hypertension.

Prehypertension in adolescents with cardiovascular risk: a comparison between type 1 diabetic patients and overweight subjects

BACKGROUND

Adolescents with type 1 diabetes and obesity present higher cardiovascular risk and ambulatory blood pressure measurements (ABPM) has been shown to predict vascular events, especially by identifying the nondipper status. The aim of our observational cross-sectional study conducted in adolescents with type 1 diabetes, overweight subjects and healthy controls was to assess mean blood pressure parameters to identify subclinical cardiovascular risk.

METHODS

The study included adolescents patients with type 1 diabetes followed in our Pediatric Department in University of Catania between January 2011 and 2013. A total of 60 patients were enrolled, and 48 (32 male and 16 female) completed the study. For each subject we performed systolic and diastolic Ambulatory Blood Pressure Measurements (ABPM) during wakefulness and sleep recording blood pressure every 30 min for 24 h with the Tonoport V/2 GE CardioSoft V6.51 device. We compared the data of patients with those of overweight subjects and healthy controls.

RESULTS

ABPM revealed no significant difference between type 1 diabetic patients and overweight subjects in 24 h Systolic, 24 h Diastolic, Day-time Systolic, Night-time systolic and Day-time Diastolic blood pressure values but significantly different values in Night-time Diastolic blood pressure values (p < 0.001). We found significant differences between type 1 diabetic patients and healthy controls in all 24 h Systolic (p < 0.001), 24 h Diastolic (p < 0.01), Day-time Systolic (p < 0.01), Night-time Systolic (p < 0.001), Day-time Diastolic (p < 0.05) and Night-time Diastolic (p < 0.001) blood pressure values. We detected hypertension in 12/48 (25%) type 1 diabetic patients and in 10/48 overweight subjects (p = 0.62; OR 1.2; CI 0.48-3.29), whereas no-one of healthy controls presented hypertension (p < 0.001). We observed nondipper pattern in 40/48 (83.3%) type 1 diabetic patients, in 33/48 (68.8%) overweight subjects (p = 0.094; OR 2.27; CI 0.85-6.01), and in 16/48 (33.3%) of healthy controls (p < 0.001; OR 10; CI 3.79-26.3).

CONCLUSIONS

ABPM studies might help to define a subset of patients at increased risk for the development of hypertension. In evaluating blood pressure in type 1 diabetes and overweight subjects, ABPM should be used since a reduced dipping can indicate incipient hypertension.

Paraventricular nucleus is involved in the central pathway of adipose afferent reflex in rats

Increasing evidence indicates a link between sympathetic nervous system activation and obesity, but the underlying mechanisms remain elusive. The adipose afferent reflex (AAR) is a sympathoexcitatory reflex that is activated by afferent neurotransmission from the white adipose tissue (WAT). This study aimed to investigate whether the hypothalamic paraventricular nucleus (PVH) is an important component of the central neurocircuitry of the AAR. In anesthetized rats, the discharge activity of individual PVH neurons was recorded in vivo. Activation of WAT afferents was initiated by capsaicin injection, and the AAR was evaluated by monitoring renal sympathetic nerve activity (RSNA) and mean arterial pressure (MAP) responses. The responses of PVH neurons to activation of WAT afferents were evaluated by c-fos immunoreactivity and the discharge activity of individual PVH neurons, which was recorded using extracellular single-unit recording. After activation of WAT afferents, both individual PVH neuron discharge activity and c-fos immunoreactivity increased. Bilateral selective lesions of the neurons in the PVH with kainic acid abolished the AAR. These results indicate that PVH is an important component of the central neurocircuitry of the AAR.

Does the sympathetic nervous system contribute to the pathophysiology of metabolic syndrome?

The metabolic syndrome (MS), formally known as syndrome X, is a clustering of several risk factors such as obesity, hypertension, insulin resistance, and dislypidemia which could lead to the development of diabetes and cardiovascular diseases (CVD). The frequent changes in the definition and diagnostic criteria of MS are indications of the controversy and the challenges surrounding the understanding of this syndrome among researchers. Obesity and insulin resistance are leading risk factors of MS. Moreover, obesity and hypertension are closely associated to the increase and aggravation of oxidative stress. The recommended treatment of MS frequently involves change of lifestyles to prevent weight gain. MS is not only an important screening tool for the identification of individuals at high risk of CVD and diabetes but also an indicator of suitable treatment. As sympathetic disturbances and oxidative stress are often associated with obesity and hypertension, the present review summarizes the role of sympathetic nervous system and oxidative stress in the MS.

Predictors of blood pressure response: Obesity is associated with a less pronounced treatment response after renal denervation

OBJECTIVES

The purpose of this study was to identify predictors of BP response.

BACKGROUND

Catheter-based renal denervation (RDN) causes significant blood pressure (BP) reductions in a large number of patients with resistant hypertension.

METHODS

One hundred one consecutive patients with resistant hypertension who underwent RDN with the Symplicity™ catheter were included in this retrospective study. Primary endpoint was the change in office systolic BP after 6 months. Uni- and multivariate logistic regression analyses were performed to detect baseline predictors of a significant BP response 6 months after RDN (age, gender, office and ambulatory BP, renal function, body mass index [BMI], diabetes mellitus, antihypertensive medication, number of ablations).

RESULTS

The procedure was technically uneventful in all patients. Mean BP at baseline was 166.6/90.2 ± 22.5/16.4 mmHg and decreased by -14.7 (P < 0.0001)/-5.3 (P < 0.001) ± 22.8/14.1 mm Hg at 6-month follow-up. Similarly, paired analysis of 24-hr-ambulatory BP measurement (n = 71) showed a significant reduction of mean systolic BP by 6.8 ± 14.4 mm Hg (P < 0.0002). Upon univariate analyses, a higher baseline office systolic BP (P < 0.0001) and lower BMI (P = 0.014) were identified as significant predictors of the magnitude of BP response after 6 months. Importantly, on multivariate analysis, baseline office systolic BP (standardized ß = -0.46; r = -0.47; P < 0.0001) and BMI (standardized ß = 0.21; r = 0.95; P = 0.019) remained significant.

CONCLUSION

Blood pressure reductions after RDN were more pronounced in patients with higher baseline blood pressure and lower BMI. These findings may have implications regarding patient selection for renal denervation. © 2015 Wiley Periodicals, Inc.

Reduced carotid baroreceptor distensibility-induced baroreflex resetting contributes to impairment of sodium regulation in rats fed a high-fat diet

Decreased carotid arterial compliance has been reported in obese subjects and animals. Carotid baroreceptors are located at the bifurcation of the common carotid artery, and respond to distension of the arterial wall, suggesting that higher pressure is required to obtain the same distension in obese subjects and animals. A hyperosmotic NaCl solution induces circulatory volume expansion and arterial pressure (AP) increase, which reflexively augment renal excretion. Thus, we hypothesized that sodium regulation via the baroreflex might be impaired in response to chronic hyperosmotic NaCl infusion in rats fed a high-fat diet. To examine this hypothesis, we used rats fed a high-fat (Fat) or normal (NFD) diet, and measured mean AP, water and sodium balance, and renal function in response to chronic infusion of hyperosmotic NaCl solution via a venous catheter. Furthermore, we examined arterial baroreflex characteristics with static open-loop analysis and distensibility of the common carotid artery. Significant positive water and sodium balance was observed on the 1st day of 9% NaCl infusion; however, this disappeared by the 2nd day in Fat rats. Mean AP was significantly higher during 9% NaCl infusion in Fat rats compared with NFD rats. In the open-loop analysis of carotid sinus baroreflex, a rightward shift of the neural arc was observed in Fat rats compared with NFD rats. Furthermore, distensibility of the common carotid artery was significantly reduced in Fat rats. These results indicate that a reduced baroreceptor distensibility-induced rightward shift of the neural arc might contribute to impairment of sodium regulation in Fat rats.

Neural innervation of white adipose tissue and the control of lipolysis

White adipose tissue (WAT) is innervated by the sympathetic nervous system (SNS) and its activation is necessary for lipolysis. WAT parasympathetic innervation is not supported. Fully-executed SNS-norepinephrine (NE)-mediated WAT lipolysis is dependent on β-adrenoceptor stimulation ultimately hinging on hormone sensitive lipase and perilipin A phosphorylation. WAT sympathetic drive is appropriately measured electrophysiologically and neurochemically (NE turnover) in non-human animals and this drive is fat pad-specific preventing generalizations among WAT depots and non-WAT organs. Leptin-triggered SNS-mediated lipolysis is weakly supported, whereas insulin or adenosine inhibition of SNS/NE-mediated lipolysis is strongly supported. In addition to lipolysis control, increases or decreases in WAT SNS drive/NE inhibit and stimulate white adipocyte proliferation, respectively. WAT sensory nerves are of spinal-origin and sensitive to local leptin and increases in sympathetic drive, the latter implicating lipolysis. Transsynaptic viral tract tracers revealed WAT central sympathetic and sensory circuits including SNS-sensory feedback loops that may control lipolysis.

Growth hormone secretagogue receptor deficiency in mice protects against obesity-induced hypertension

Abstract Growth hormone secretagogue receptor (GHS-R) signaling has been associated with growth hormone release, increases in food intake and pleiotropic cardiovascular effects. Recent data demonstrated that acute GHS-R antagonism leads to increases in mean arterial pressure mediated by the sympathetic nervous system in rats; a highly undesirable effect if GHS-R antagonism was to be used as a therapeutic approach to reducing food intake in an already obese, hypertensive patient population. However, our data in conscious, freely moving GHS-R deficient mice demonstrate that chronic absence of GHS-R signaling is protective against obesity-induced hypertension. GHS-R deficiency leads to reduced systolic blood pressure variability (SBPV); in response to acute high-fat diet (HFD)-feeding, increases in the sympathetic control of SBPV are suppressed in GHS-R KO mice. Our data further suggest that GHS-R signaling dampens the immediate HFD-mediated increase in spontaneous baroreflex sensitivity. In diet-induced obesity, absence of GHS-R signaling leads to reductions in obesity-mediated hypertension and tachycardia. Collectively, our findings thus suggest that chronic blockade of GHS-R signaling may not result in adverse cardiovascular effects in obesity.

PI3K signaling: A key pathway in the control of sympathetic traffic and arterial pressure by leptin

The adipocyte-derived hormone, leptin, is a master regulator of energy homeostasis. Leptin action in the central nervous system also contributes to arterial pressure regulation through its capacity to increase renal sympathetic outflow. The accumulating evidence pointing to a key role for leptin in the adverse sympathetic and cardiovascular consequences of excessive adiposity highlight the importance of understanding the mechanisms underlying the sympathetic and cardiovascular effects of leptin. The ability of the leptin receptor to stimulate various intracellular pathways allows leptin to regulate physiological processes in a specific manner. In this review, we examine the role of the PI3K pathway emanating from the leptin receptor in mediating the sympathetic and arterial pressure effects of leptin. We also discuss the relevance of PI3K signaling for obesity-induced hypertension through its role in mediating selective leptin resistance.

Protein phosphatase 1b in the solitary tract nucleus is necessary for normal baroreflex function

Despite positive metabolic effects, genetic deletion of protein phosphatase 1b (PTP1b) results in sympathetically mediated elevations in arterial pressure (AP) in mice. Because several PTP1b-regulated peptides also impair the baroreflex sensitivity (BRS) for control of heart rate (HR), we hypothesized that PTP1b in the solitary tract nucleus (NTS) participates in the maintenance of resting baroreflex function. To test this hypothesis, we performed acute bilateral microinjection of an allosteric PTP1b inhibitor (100 nM/120 nL) in the NTS of urethane/chloralose anesthetized Sprague-Dawley rats and assessed the BRS, responses to cardiac vagal chemosensitive fiber activation, and resting AP and HR before and after the injection. PTP1b inhibition impaired the BRS for bradycardia (n = 6; 0.93 ± 0.14 baseline vs. 0.48 ± 0.04 at 10 minutes vs. 0.49 ± 0.04 millisecond/mm Hg at 60 minutes; P < 0.01), with no significant effect on the BRS for tachycardia (0.30 ± 0.16 baseline vs. 0.24 ± 0.08 at 10 minutes vs. 0.24 ± 0.12 millisecond/mm Hg at 60 minutes). The reduced BRS for bradycardia was associated with a significant decrease in alpha-adrenergic responsiveness to phenylephrine at 60 minutes after PTP1b inhibition. Injection of the PTP1b inhibitor in the NTS elicited transient decreases in AP and HR in these animals. However, there was no effect of the inhibitor on depressor or bradycardic responses elicited by activation of cardiac vagal chemosensitive fibers, which converge with baroreceptor afferents in the NTS. These results suggest that PTP1b within the NTS may be a novel molecular mechanism for preservation of resting baroreflex function and provides further evidence for deleterious cardiovascular effects associated with PTP1b inhibition.

Decreased adrenergic tone in acromegaly: evidence from direct recording of muscle sympathetic nerve activity

OBJECTIVE

Sympathovagal imbalance has been shown in acromegaly by indirect measurements of adrenergic tone. Data regarding direct measurement of sympathetic activity are lacking as yet. Aim of this study was to assess the adrenergic tone through direct recording of muscle sympathetic nerve activity (MSNA) in acromegalic patients.

DESIGN

Fifteen patients (age 26-66 years, eight women) with newly diagnosed active acromegaly without hyperprolactinaemia, pituitary hormone deficiencies, obstructive sleep apnoea and cardiac hypertrophy, and 15 healthy subjects matched for age, sex and body mass index were recruited. After evaluating anthropometric and echocardiographic parameters, anterior pituitary function, glucose and lipid metabolism, and measuring plasma leptin, direct recording of sympathetic outflow via the microneurographic technique was performed.

RESULTS

For similar anthropometric and metabolic parameters in patients and controls, HOMA index was significantly increased in the former (4·2 ± 2·39 vs 1·6 ± 0·19, P < 0·001). Surprisingly, this finding of insulin resistance was accompanied by a marked sympathetic inhibition (MSNA 18·3 ± 8·10 vs 37·3 ± 6·48 bursts/min, P < 0·0001, respectively in patients and controls). A reduction in plasma leptin (1·6 ± 1·04 vs 6·5 ± 2·01 μg/l, P < 0·0001) was also recorded in the patients. MSNA was positively correlated with leptin (P < 0·0001).

CONCLUSIONS

Newly diagnosed acromegalic patients without cardiac hypertrophy display a decreased sympathetic outflow in spite of insulin resistance. This finding might be related to hypoleptinaemia.

Anticontractile Effect of Perivascular Adipose Tissue and Leptin are Reduced in Hypertension

Leptin causes vasodilatation both by endothelium-dependent and -independent mechanisms. Leptin is synthesized by perivascular adipose tissue (PVAT). The hypothesis of this study is that a decrease of leptin production in PVAT of spontaneously hypertensive rats (SHR) might contribute to a diminished paracrine anticontractile effect of the hormone. We have determined in aorta from Wistar-Kyoto (WKY) and SHR (i) leptin mRNA and protein levels in PVAT, (ii) the effect of leptin and PVAT on contractile responses, and (iii) leptin-induced relaxation and nitric oxide (NO) production. Leptin mRNA and protein expression were significantly lower in PVAT from SHR. Concentration-response curves to angiotensin II were significantly blunted in presence of PVAT as well as by exogenous leptin (10⁻⁹ M) only in WKY. This anticontractile effect was endothelium-dependent. Vasodilatation induced by leptin was smaller in SHR than in WKY, and was also endothelium-dependent. Moreover, release of endothelial NO in response to acute leptin was higher in WKY compared to SHR, but completely abolished in the absence of endothelium. In conclusion, the reduced anticontractile effect of PVAT in SHR might be attributed to a reduced PVAT-derived leptin and to an abrogated effect of leptin on endothelial NO release probably due to an impaired activation of endothelial NO synthase.

Anticontractile Effect of Perivascular Adipose Tissue and Leptin are Reduced in Hypertension

Leptin causes vasodilatation both by endothelium-dependent and -independent mechanisms. Leptin is synthesized by perivascular adipose tissue (PVAT). The hypothesis of this study is that a decrease of leptin production in PVAT of spontaneously hypertensive rats (SHR) might contribute to a diminished paracrine anticontractile effect of the hormone. We have determined in aorta from Wistar-Kyoto (WKY) and SHR (i) leptin mRNA and protein levels in PVAT, (ii) the effect of leptin and PVAT on contractile responses, and (iii) leptin-induced relaxation and nitric oxide (NO) production. Leptin mRNA and protein expression were significantly lower in PVAT from SHR. Concentration-response curves to angiotensin II were significantly blunted in presence of PVAT as well as by exogenous leptin (10(-9) M) only in WKY. This anticontractile effect was endothelium-dependent. Vasodilatation induced by leptin was smaller in SHR than in WKY, and was also endothelium-dependent. Moreover, release of endothelial NO in response to acute leptin was higher in WKY compared to SHR, but completely abolished in the absence of endothelium. In conclusion, the reduced anticontractile effect of PVAT in SHR might be attributed to a reduced PVAT-derived leptin and to an abrogated effect of leptin on endothelial NO release probably due to an impaired activation of endothelial NO synthase.

Obesity: from the agricultural revolution to the contemporary pediatric epidemic

Obesity is pandemic in Western society. Currently, approximately 100 million Americans are overweight (body mass index > 25 kg/m2) or obese (body mass index > 30 kg/m2). The pandemic is largely attributable to the relatively recent (from an evolutionary perspective) adoption of a sedentary lifestyle, coupled with the high availability of foods with high caloric content in Western cultures. These factors superimposed on dated genotypes have given rise to the global obesity epidemic. Over the past two decades, the discovery of leptin and other new molecules (e.g., adiponectin, resistin, ghrelin) has shed significant light on the pathophysiologic mechanisms of obesity-related morbidities, many of which became apparent through human epidemiologic studies during the last half of the 20th century. Of high concern for modern Western societies is the pediatric obesity epidemic, which stands to cripple Western cultures, both literally and financially in terms of health care costs and exhaustion of finite medical resources. The prevalence of childhood obesity has more than tripled since the 1960s, and 12.5 million (~17%) of children and teenagers are obese in the United States today. The rate of increasing prevalence of childhood obesity is staggering, and the collective efforts of the pediatric medical community and scientists are essential for battling the epidemic.

Activation of the melanocortin-4 receptor causes enhanced excitation in presympathetic paraventricular neurons in obese Zucker rats

Sympathetic nerve activity is increased in obesity-related hypertension. However, the central mechanisms involved in the increased sympathetic outflow remain unclear. The hypothalamic melanocortin system is important for regulating energy balance and sympathetic outflow. To understand the mechanisms by which the melanocortin systems regulates sympathetic outflow, we investigated the role of melanocortin 4 receptors (MC4R) in regulating presympathetic paraventricular nucleus (PVN) neurons. We performed whole-cell patch-clamp recordings on retrogradely labeled PVN neurons projecting to the rostral ventrolateral medulla in brain slices from obese zucker rats (OZRs) and lean zucker rats (LZRs). The MC4R agonists melanotan II (MTII) and α-melanocyte-stimulating hormone (α-MSH) increased the firing activity and depolarized the labeled PVN neurons from both LZRs and OZRs in a concentration-dependent manner. MTII produced significant greater increase in the firing activity in OZRs than in LZRs. Blocking MC4R with the specific antagonist SHU9119 had no effect on the basal firing rate but abolished the MTII-induced increase in the firing rate in both OZRs and LZRs. Furthermore, intracellular dialysis of guanosine 5'-O-(2-thodiphosphate), but not bath application of kynurenic acid and bicuculline, eliminated the MTII-induced increase in firing activity. In addition, MTII had no effect on the frequency and amplitude of glutamatergic excitatory postsynaptic currents and GABAergic inhibitory postsynaptic currents in labeled PVN neurons. Collectively, our findings suggest that MC4R contributes to the elevated excitability of PVN presympathetic neurons, which may be involved in obesity-related hypertension.

Mechanisms of obesity-induced hypertension

The relationship between obesity and hypertension is well established both in children and adults. The mechanisms through which obesity directly causes hypertension are still an area of research. Activation of the sympathetic nervous system has been considered to have an important function in the pathogenesis of obesity-related hypertension. The arterial-pressure control mechanism of diuresis and natriuresis, according to the principle of infinite feedback gain, seems to be shifted toward higher blood-pressure levels in obese individuals. During the early phases of obesity, primary sodium retention exists as a result of increase in renal tubular reabsorption. Extracellular-fluid volume is expanded and the kidney-fluid apparatus is resetted to a hypertensive level, consistent with a model of hypertension because of volume overload. Plasma renin activity, angiotensinogen, angiotensin II and aldosterone values display significant increase during obesity. Insulin resistance and inflammation may promote an altered profile of vascular function and consequently hypertension. Leptin and other neuropeptides are possible links between obesity and the development of hypertension. Obesity should be considered as a chronic medical condition, which is likely to require long-term treatment. Understanding of the mechanisms associated with obesity-related hypertension is essential for successful treatment strategies.

Exposure to a high-fat diet alters leptin sensitivity and elevates renal sympathetic nerve activity and arterial pressure in rabbits

The activation of the sympathetic nervous system through the central actions of the adipokine leptin has been suggested as a major mechanism by which obesity contributes to the development of hypertension. However, direct evidence for elevated sympathetic activity in obesity has been limited to muscle. The present study examined the renal sympathetic nerve activity and cardiovascular effects of a high-fat diet (HFD), as well as the changes in the sensitivity to intracerebroventricular leptin. New Zealand white rabbits fed a 13.5% HFD for 4 weeks showed modest weight gain but a 2- to 3-fold greater accumulation of visceral fat compared with control rabbits. Mean arterial pressure, heart rate, and plasma norepinephrine concentration increased by 8%, 26%, and 87%, respectively (P<0.05), after 3 weeks of HFD. Renal sympathetic nerve activity was 48% higher (P<0.05) in HFD compared with control diet rabbits and was correlated to plasma leptin (r=0.87; P<0.01). Intracerebroventricular leptin administration (5 to 100 microg) increased mean arterial pressure similarly in both groups, but renal sympathetic nerve activity increased more in HFD-fed rabbits. By contrast, intracerebroventricular leptin produced less neurons expressing c-Fos in HFD compared with control rabbits in regions important for appetite and sympathetic actions of leptin (arcuate: -54%, paraventricular: -69%, and dorsomedial hypothalamus: -65%). These results suggest that visceral fat accumulation through consumption of a HFD leads to marked sympathetic activation, which is related to increased responsiveness to central sympathoexcitatory effects of leptin. The paradoxical reduction in hypothalamic neuronal activation by leptin suggests a marked "selective leptin resistance" in these animals.

Evaluation of anti-obesity activity of duloxetine in comparison with sibutramine along with its anti-depressant activity: an experimental study in obese rats

5-HT and noradrenaline are important neurotransmitters that control increase in body mass and are involved in the pathophysiology of obesity and depression. Sibutramine, an established anti-obesity agent, and duloxetine, an anti-depressant agent, are serotonin noradrenaline reuptake inhibitors (SNRIs). The objective of the present study was to compare the anti-obesity effect of duloxetine with sibutramine along with its effect on blood pressure and depression in obese rats. The secondary objective of the study was to determine if a relationship exists between obesity and depression. Obesity was induced by high-fat diet (HFD) in healthy male Sprague-Dawley rats. After 5 weeks of feeding HFD, animals were overweight (17.57%) with high food intake (57.15%) in comparison with normal animals. These obese animals were treated with duloxetine (30 mg x kg(-1), p.o.) and sibutramine (5 mg x kg(-1), p.o.) for 4 weeks. Control animals were treated with duloxetine alone (30 mg x kg(-1), p.o.). Our results depict that duloxetine was as effective as sibutramine in reducing food intake, body mass, and relative adiposity, and increasing rectal temperature with an added advantage of decreasing blood pressure, which sibutramine failed to do. Besides reduction in body mass, unlike sibutramine, duloxetine improved depressive state as evaluated by despair swimming test, tail suspension test, and open field test, speculating its use as an anti-obesity agent in obese-depressive animals. Since obese control animals reflected decreased locomotor activity, a positive relationship can be speculated to exist between obesity and depression. Further studies on various antidepressant models are required to confirm this relationship.

Metabolic effects of low dose angiotensin converting enzyme inhibitor in dietary obesity in the rat

BACKGROUND AND AIMS

Given the recent observation of a local renin-angiotensin system (RAS) in adipose tissue, and its association with obesity-related hypertension, the metabolic effects of treatment with a low dose angiotensin converting enzyme inhibitor (ACEI) were investigated in a rodent model of diet-induced obesity.

METHODS AND RESULTS

Male Sprague Dawley rats were exposed to either standard laboratory chow (12% calories as fat) or palatable high fat (30% calories as fat) diet for 12 weeks. A subset from both dietary groups was given low dose ACEI in drinking water (perindopril, 0.3 mg/kg/day) throughout the study. The high fat diet increased body weight, adiposity, circulating leptin and insulin and in the liver we observed fat accumulation and increased tissue ACE activity. Treatment with perindopril decreased food intake and circulating insulin in both diet groups, and hepatic ACE activity in high fat fed animals only. Decreased plasma leptin concentration with ACE inhibition was only evident in chow fed animals. These effects were independent of any blood pressure lowering effect of ACE inhibition.

CONCLUSION

Chronic low dose ACEI treatment reduced circulating insulin and leptin levels with some reduction in food intake in chow fed rats. Fewer beneficial effects were observed in obesity, and further work is required to investigate higher ACEI doses. Our data suggest a reduction in hepatic ACE activity may affect lipid accumulation and other inflammatory responses, as well as improving insulin resistance. Our findings may have implications for maximizing the clinical benefit of ACEI in patients without overt cardiovascular complications.

The role of the sympathetic nervous system in obesity-related hypertension

Obesity is recognized as a major health problem throughout the world. Excess weight is a major cause of increased blood pressure in most patients with essential hypertension and greatly increases the risk for diabetes, cardiovascular diseases, and end-stage renal disease. Although the mechanisms by which obesity raises blood pressure are not completely understood, increased renal sodium reabsorption, impaired pressure natriuresis, and volume expansion appear to play important roles. Several potential mechanisms have been suggested to contribute to altered kidney function and hypertension in obesity, including activation of the sympathetic nervous system and the renin-angiotensin-aldosterone system, as well as physical compression of the kidneys, especially when visceral obesity is present. Activation of the sympathetic nervous system in obesity may be due, in part, to hyperleptinemia and other factors secreted by adipocytes and the gastrointestinal tract, activation of the central nervous system melanocortin pathway, and baroreceptor dysfunction.

The pathophysiology of hypertension in systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a chronic autoimmune inflammatory disorder that predominantly affects women during their reproductive years. Although SLE can affect any organ system, the kidneys are prominently involved in the form of immune complex glomerulonephritis. In addition, in women with SLE, risk for the development of cardiovascular disease is dramatically increased. Hypertension is a major risk factor for cardiovascular disease and is highly prevalent in women with SLE. Nevertheless, there has been little exploration of the pathophysiological mechanisms that promote SLE hypertension. This review discusses the role of several mechanisms, with an emphasis on the kidney, in SLE hypertension. These mechanisms include the renin-angiotensin system, endothelin, oxidative stress, sex steroids, metabolic changes, peroxisome proliferator-activated receptor-gamma, and, perhaps most importantly, chronic inflammation and cytokines. Growing evidence suggests a link between chronic inflammation and hypertension. Therefore, elucidation of mechanisms that promote SLE hypertension may be of significant value not only for patients with SLE, but also for a better understanding of the basis for essential hypertension.

Modulation of blood pressure by central melanocortinergic pathways

BACKGROUND

Weight gain and weight loss are associated with changes in blood pressure through unknown mechanisms. Central melanocortinergic signaling is implicated in the control of energy balance and blood pressure in rodents, but there is no information regarding such an association with blood pressure in humans.

METHODS

We assessed blood pressure, heart rate, and urinary catecholamines in overweight or obese subjects with a loss-of-function mutation in MC4R, the gene encoding the melanocortin 4 receptor, and in equally overweight control subjects. We also examined the effects of an MC4R agonist administered for 7 days in 28 overweight or obese volunteers.

RESULTS

The prevalence of hypertension was markedly lower in the MC4R-deficient subjects than in the control subjects (24% vs. 53%, P=0.009). After the exclusion of subjects taking antihypertensive medications, blood-pressure levels were significantly lower in MC4R-deficient subjects than in control subjects, with mean (+/-SE) systolic blood pressures of 123+/-14 mm Hg and 131+/-12 mm Hg, respectively (P=0.02), and mean diastolic blood pressures of 73+/-10 mm Hg and 79+/-7 mm Hg, respectively (P=0.03). As compared with control subjects, MC4R-deficient subjects had a lower increase in heart rate on waking (P=0.007), a lower heart rate during euglycemic hyperinsulinemia (P<0.001), and lower 24-hour urinary norepinephrine excretion (P=0.04). The maximum tolerated daily dose of 1.0 mg of the MC4R agonist led to significant increases of 9.3+/-1.9 mm Hg in systolic blood pressure and of 6.6+/-1.1 mm Hg in diastolic blood pressure (P<0.001 for both comparisons) at 24 hours, as compared with placebo. Differences in blood pressure were not explained by changes in insulin levels; there were no significant adverse events.

CONCLUSIONS

Results of our genetic and pharmacologic studies implicate melanocortinergic signaling in the control of human blood pressure through an insulin-independent mechanism.

Mechanisms mediating renal sympathetic activation to leptin in obesity

Leptin plays a critical role in the control of energy homeostasis. The sympathetic cardiovascular actions of leptin have emerged as a potential link between obesity and hypertension. We previously demonstrated that in mice, modest obesity induced by 10 wk of a high-fat diet is associated with preservation of leptin ability to increase renal sympathetic nerve activity (SNA) despite the resistance to the metabolic effects of leptin. Here, we examined whether selective leptin resistance exists in mice with late-stage diet-induced obesity (DIO) produced by 20 wk of a high-fat diet. The decrease in food intake and body weight induced by intraperitoneal or intracerebroventricular injection of leptin was significantly attenuated in the DIO mice. Regional SNA responses to intravenous leptin were also attenuated in DIO mice. In contrast, intracerebroventricularly administered leptin caused contrasting effects on regional SNA in DIO mice. Renal SNA response to intracerebroventricular leptin was preserved, whereas lumbar and brown adipose tissue SNA responses were attenuated. Intact renal SNA response to leptin combined with the increased cerebrospinal fluid leptin levels in DIO mice represents a potential mechanism for the adverse cardiovascular consequences of obesity. Lastly, we examined the role of phosphoinositol-3 kinase (PI3K) and melanocortin receptors (MCR) in mediating the preserved renal SNA response to leptin in obesity. Presence of PI3K inhibitor (LY294002) or MC3/4R antagonist (SHU9119) significantly attenuated the renal SNA response to leptin in DIO and agouti obese mice. Our results demonstrate the importance of PI3K and melanocortin receptors in the transduction of leptin-induced renal sympathetic activation in obesity.

Relation of heart rate with cardiovascular disease in normal-weight individuals: the Chicago Heart Association Detection Project in Industry

The authors investigated the association of resting heart rate (RHR) with cardiovascular disease (CVD) risk factors and mortality among normal-weight individuals. Using data from our cohort (baseline examination in 1967-1973), individuals with a body mass index of 18.5 to 24.9 kg/m(2) (men [n=3724] and women [n=4929] aged 18-39; men [n=1959] and women [n=3735] aged 40-59), were grouped by RHR: <75, 75-84, and > or =85 beats per minute (bpm). A lower RHR was associated with lower mean blood pressure (BP) and cigarette use in each subgroup and total cholesterol (TC) and diabetes in men (P<.05). After a 32-year follow-up, hazard ratios (95% confidence intervals) for CVD mortality for an RHR <75 compared with > or =85 bpm adjusted for age, race, education level, BP, cigarette use, diabetes, and TC were 0.58 (0.34-0.84), 0.73(0.56-0.95), and 0.77 (0.61-0.98) for men aged 18 to 39 and men and women aged 40 to 59, respectively. In women aged 18 to 39, the relationship was not significant. In general, normal-weight individuals with lower RHRs have lower levels of CVD risk factors and mortality.