Jagadeeswaran Indumathy

Association of sympathovagal imbalance with obesity indices, and abnormal metabolic biomarkers and cardiovascular parameters

PROBLEM Pathophysiological mechanisms contributing to abnormal cardiovascular (CV) parameters in obesity have not been fully elucidated. Role of sympathovagal imbalance (SVI) in the prediction of abnormalities in CV functions in obesity has not been studied. METHODS Anthropometric indices, CV parameters, autonomic function tests (AFTs) such as spectral heart rate variability (HRV) analysis, heart rate and blood pressure response to standing, deep breathing, and isometric-handgrip, and biochemical parameters like insulin resistance (HOMA-IR), lipid risk factors and inflammatory marker [high-sensitive C-reactive protein (hsCRP)] were assessed in control group (non-obese, n=43) and obese group (n=45). Association of anthropometric indices and abnormal CV parameters with low-frequency to high-frequency ratio (LF-HF) of HRV was performed by Pearsons correlation. Independent contribution of anthropometric indices and abnormal CV parameters to LF-HF was assessed by using a multiple regression analysis. LF-HF prediction of rate-pressure product (RPP), the indicator of CV dysfunction was assessed by logistic regression. RESULTS LF-HF, the marker of SVI was more in obese group compared to control group. AFTs of sympathetic activity were increased and of parasympathetic activity were reduced in obese group. Anthropometric indices, HOMA-IR, lipid risk factors and hsCRP were correlated with LF-HF. These metabolic biomarkers had independent contribution to SVI. Among, anthropometric indices, waist-to-height ratio (WHtR) had maximum association with LF-HF. LF-HF had significant prediction of RPP in obese group. CONCLUSION SVI in obesity is due to both increased sympathetic and decreased vagal activity. Abnormal CV parameters in obesity are linked to SVI, which is contributed by insulin resistance, dyslipidaemia and low-grade inflammation. LF-HF predicts abnormal CV parameters in obesity.

Decreased baroreflex sensitivity is linked to sympathovagal imbalance, body fat mass and altered cardiometabolic profile in pre-obesity and obesity

OBJECTIVE Though decreased baroreflex sensitivity (BRS), the predictor of cardiac morbidities and mortality has been reported in obesity, the mechanisms and metabolic biomarkers influencing BRS have not been studied. We aimed to assess the difference in cardiovascular (CV) risk profile in pre-obesity and obesity, and the contribution of body composition and cardiometabolic factors to CV risks in these two conditions. METHODS Obesity indices, body composition, blood pressure variability and autonomic function test parameters were recorded in 223 subjects divided into controls (n=72), pre-obese (n=77) and obese (n=74) groups. Insulin resistance (HOMA-IR), atherogenic index (AI), leptin, adiponectin, inflammatory and oxidative stress parameters were measured. Association and independent contribution of altered cardiometabolic parameters with BRS were performed by Pearsons correlation and multiple regression analysis, respectively. RESULTS BRS was significantly decreased in pre-obese and obese group compared to controls. Sympathovagal imbalance (SVI) in the form of increased sympathetic and decreased parasympathetic cardiac drives was observed in pre-obesity and obesity. There was significant difference in general markers of obesity (body mass index, and waist-to-hip ratio), between pre-obese and obese group, however no such difference was observed in body composition and cardiometabolic parameters between the two groups. AI, high sensitive C-reactive protein (hs-CRP) and ratio of basal metabolism to body fat (BM/BF) in pre-obese group, and AI, HOMA-IR, leptin, adiponectin, ratio of basal metabolism to body weight (BM/BW), BM/BF, inflammatory and oxidative stress markers in obese group had independent contribution to BRS. Among these metabolic biomarkers, BRS had maximum association with leptin (β=0.532, p=0.000) in the obese group and hs-CRP (β=0.445, p=0.022) in the pre-obese group. CONCLUSIONS The present study demonstrates decreased BRS, an important marker of increased CV risk in pre-obesity and obesity. The intensity of cardiometabolic derangements and CV risk was comparable between pre-obese and obese subjects. BM/BF ratio appears to be a better marker of metabolic activity in pre-obesity and obesity. SVI and increased basal metabolism appear to be the physiological link between metabolic derangements and CV risks in both pre-obesity and obesity.

Prehypertension status, cardiometabolic risks, and decreased baroreflex sensitivity are linked to sympathovagal imbalance in salt-preferring individuals

Abstract Salt preference has been reported to cause sympathovagal imbalance (SVI) and prehypertension. We investigated the role of inflammation, insulin resistance (IR), hyperlipidemia, and oxidative stress (OS) in genesis of SVI and cardiovascular (CV) risks in salt-preferring prehypertensives. The subjects were divided into no-salt-preferring (NSP, n = 87) and salt-preferring (SP, n = 89) group based on their preference for salted food. Body mass index (BMI), blood pressure (BP) variability parameters including baroreflex sensitivity (BRS), heart rate variability (HRV) indices, autonomic function tests, IR, lipid risk factors, inflammatory and OS markers, and renin were measured in both the groups. Based on the contribution of various cardiometabolic risks to low-frequency–high-frequency (LF–HF) ratio of HRV, the marker of SVI was assessed by multiple-regression analysis. Prediction of prehypertension status by the LF–HF ratio was assessed by bivariate logistic regression. BMI, heart rate, BP parameters, cardiac output, total peripheral resistance, LF–HF ratio, IR, atherogenic index, inflammatory, and OS markers were significantly increased, and BRS was significantly decreased in the SP group compared with the NSP group. There was an independent association of IR, atherogenic index, markers of inflammation and OS, and BRS with the LF–HF ratio in SP subjects, and the LF–HF ratio had significant prediction of prehypertension status in these subjects. It was concluded that IR, low-grade inflammation, atherogenic lipid profile, and OS contribute to SVI in SP subjects. Decreased BRS (the marker of CV risk) is linked to SVI, and SVI predicts prehypertension status in SP subjects.

Effect of gender on food intake, adiposity and immunological responses following lesion of ventromedial hypothalamus in albino Wistar rats

Background and Aim: The present study was conducted to assess the gender difference in the role of ventromedial hypothalamus (VMH) on the regulation of food intake (FI), body weight (BW), and immunological responses in albino Wistar rats. Methods: A total of 24 albino Wistar rats were taken for the study and were divided equally into two groups: VMH Group and control Group for VMH lesion, with six male and six female rats in each group. In the experimental group, bilateral electrolytic lesion of the respective nuclei was performed by stereotaxy and postlesion parameters were recorded. In the control group, sham lesion was made. Male-female difference in each parameter was determined. Results: Following VMH lesion, FI increased significantly in both the sexes ( P P P P Conclusion: The above-mentioned findings suggest that VMH is an important center for satiety and adiposity in rat models and has differential influence on control of FI and BW gain in male and female rats. The impact of VMH on immunity is stimulatory and the system is more developed in males.

Effect of gender on cardiovascular and metabolic risk profile in young adult indian population

Background and Aim: Gender difference has been documented in the cardiovascular (CV) morbidity and mortality associated with obesity. Therefore, the aim of the present study was to determine the gender difference in CV and metabolic risk profile in apparently healthy young adult preobese and obese individuals. Methods: Obesity indices, body composition, blood pressure variability, and autonomic function test parameters were recorded in 270 individuals divided into control (male n = 43; female n = 47), preobese (male n = 48; female n = 42), and obese (male n = 44; female n = 46) groups. Homeostatic model assessment-insulin resistance, atherogenic index, leptin, adiponectin, and inflammatory and oxidative stress parameters were measured. The gender difference in CV and metabolic profile between the control, preobese, and obese groups was performed by one-way ANOVA. Results: The abdominal adiposity was more in females as compared to males in both preobese and obese individuals. However, the increased CV risk (decreased heart rate variability) was observed in obese male compared to obese female individuals, which is supported by the increased inflammatory profile (increased interleukin-6) in males compared to females. There was no much gender difference in most of the CV and metabolic parameters in control, preobese, and obese individuals. Conclusion: In the present study, we could not assess much difference in gender between the preobese and obese groups as CV risks and metabolic derangements have not been significantly established in these younger individuals who were in their early phases of preobesity and obesity.

Decreased rate pressure product by yoga therapy in the first-degree relatives of type 2 diabetics is linked to the decrease in body mass index

Although cardiovascular (CV) risks are reported in the first-degree relatives (FDRs) of type 2 diabetics, the role of yoga therapy on these CV risks is not known. We investigated the effects of 12 weeks structured yoga therapy on rate pressure product (RPP), the marker of CV risk, in these high-risk subjects. FDRs of type 2 diabetics (n = 49) were trained and allowed to practice 12 weeks of structured yoga program. Body mass index (BMI), heart rate (HR), blood pressure (BP), and RPP were measured, and all these parameters were recorded and compared between pre- and post-yoga therapy periods. Bivariate logistic regression was performed to assess the contribution of BMI to change in RPP in these subjects. There was significant reduction in BMI (P = 0.0002), HR, BP, and RPP (P < 0.001) in these subjects. Bivariate logistic regression demonstrated independent more significant contribution of BMI to RPP in postyoga therapy period as compared to preyoga therapy period. It was concluded that FDRs of type 2 diabetics have high RPP and BP that decrease significantly following 12 weeks practice of yoga.

Cardiovascular risk is linked to body mass index in first-degree relatives of type 2 diabetics

Although cardiovascular (CV) risks are reported in first-degree relatives (FDR) of type 2 diabetics, the pathophysiological mechanisms contributing to these risks are not known. We investigated the association of CV risks with body mass index (BMI) in these subjects. BMI, basal heart rate (BHR), blood pressure (BP), and rate-pressure product (RPP) were measured and analyzed in age-matched subjects of study group (FDR of type 2 diabetics, n = 58) and control group (subjects with no family history of diabetes, n = 92). BMI, BP, BHR, and RPP were significantly increased (P < 0.0001) in the study group compared to the control group. Sympathovagal imbalance in the study group was due to concomitant sympathetic activation and vagal inhibition. Bivariate logistic regression showed significant prediction (odds ratio: 2.12, confidence interval: 1.120–5.317, P = 0.009) of BMI to increased RPP, the marker of CV risk, in the study group, but not in the control group. CV risk in FDR of type 2 diabetics is linked to BMI.

Myocardial works stress is linked to sympathovagal imbalance in prehypertensives

The link of sympathovagal imbalance (SVI) to rate-pressure product (RPP), the marker of myocardial stress in prehypertension has not been elucidated. Body mass index (BMI), cardiovascular parameters, spectral analysis of heart rate variability, and RPP were assessed in young normotensives (n = 58) and prehypertensives (n = 58). BMI, heart rate, blood pressure, RPP and low-frequency to high-frequency (LF-HF) ratio were more in prehypertensives compared to normotensives. Pearson correlation revealed a significant association of LF-HF with RPP in prehypertensives, but not in normotensives. Bivariate regression analysis revealed the independent contribution of LF-HF ratio to RPP in prehypertensives. It was concluded that SVI contributed to myocardial work stress in young prehypertensives.

Vagal withdrawal is similar in preobese and obese Indian adults

Preobesity and obesity are among the leading causes of preventable deaths worldwide. Decreased vagal activities and high basal heart rate (BHR) observed in obesity have been reported to be associated with the future cardiovascular events. Therefore, in the present study, the difference in BHR and time domain indices (TDI) among preobese and obese subjects has been assessed. Body mass index, BHR, and TDI of heart rate variability were assessed in overweight (n = 50) and obese (n = 50) group subjects. BHR and TDI, which primarily reflect the parasympathetic cardiac modulation, were not found to be significantly different between the preobese and obese subjects. To conclude, high BHR and decreased TDI observed in the studied population suggest that there was no difference in vagal activities between the preobese and obese subjects.

Sympathovagal imbalance in obesity: Cardiovascular perspectives

Obesity is an independent predictor of cardiovascular (CV) morbidity and mortality. Irrespective of the etiology, sympathovagal imbalance (SVI) in the form of sympathetic overactivity and vagal withdrawal has been recognized as the central pathophysiological mechanism involved in the genesis of obesity. Also, SVI has been reported to be the potential contributor to the obesity related co-morbidities such as diabetes, insulin resistance, hypertension, dyslipidemia and CV dysfunctions. In this review, we have analyzed the role of SVI in the development of obesity and its association with the genesis of CV dysfunctions. We have emphasized the role of lifestyle modification and pharmacological therapy in restoring the sympathovagal balance and its link to prevent the occurrence of CV diseases in overweight and obese individuals.