Venugopal Lalitha

Sympathovagal imbalance contributes to prehypertension status and cardiovascular risks attributed by insulin resistance, inflammation, dyslipidemia and oxidative stress in first degree relatives of type 2 diabetics.

Background Though 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 sympathovagal imbalance (SVI) with CV risks in these subjects. Subjects and Methods Body mass index (BMI), basal heart rate (BHR), blood pressure (BP), rate-pressure product (RPP), spectral indices of heart rate variability (HRV), autonomic function tests, insulin resistance (HOMA-IR), lipid profile, inflammatory markers, oxidative stress (OS) marker, rennin, thyroid profile and serum electrolytes were measured and analyzed in subjects of study group (FDR of type 2 diabetics, n = 72) and control group (subjects with no family history of diabetes, n = 104). Results BMI, BP, BHR, HOMA-IR, lipid profile, inflammatory and OS markers, renin, LF-HF (ratio of low-frequency to high-frequency power of HRV, a sensitive marker of SVI) were significantly increased (p<0.0001) in study group compared to the control group. SVI in study group was due to concomitant sympathetic activation and vagal inhibition. There was significant correlation and independent contribution of markers of insulin resistance, dyslipidemia, inflammation and OS to LF-HF ratio. Multiple-regression analysis demonstrated an independent contribution of LF-HF ratio to prehypertension status (standardized beta 0.415, p<0.001) and bivariate logistic-regression showed significant prediction (OR 2.40, CI 1.128–5.326, p = 0.002) of LF-HF ratio of HRV to increased RPP, the marker of CV risk, in study group. Conclusion SVI in FDR of type 2 diabetics occurs due to sympathetic activation and vagal withdrawal. The SVI contributes to prehypertension status and CV risks caused by insulin resistance, dyslipidemia, inflammation and oxidative stress in FDR of type 2 diabetics.

Sympathovagal imbalance in young prehypertensives: importance of male-female difference.

Introduction:Although the prevalence of prehypertension is high, the pathophysiological mechanisms and the effects of gender in its causation have not yet been fully understood. Methods:Body mass index, waist-to-hip ratio, basal heart rate, blood pressure, rate pressure product and spectral indices of heart rate variability were reordered and analyzed in young normotensive (n = 344) and prehypertensive (n = 69) subjects. Each group was categorized into male and female subgroups. Results:Ratio of low-frequency to high-frequency powers (LF-HF ratio) of heart rate variability spectrum, the sensitive marker of sympathovagal imbalance (SVI), was significantly more increased (P < 0.001) in male prehypertensives compared with female prehypertensives. Although SVI in prehypertensives was found to be due to both sympathetic activation in the form of increased low-frequency power normalized (increased LFnu) and vagal inhibition in the form of decreased high-frequency power normalized (decreased HFnu), contribution of vagal withdrawal was more in males. LF-HF ratio was significantly correlated with body mass index, waist-to-hip ratio, basal heart rate, blood pressure and rate pressure product by Pearson correlation analysis. Furthermore, multiple regression analysis demonstrated an independent relationship between LF-HF ratio and gender (P = 0.000) and prehypertension status (P = 0.000) in both normotensives and prehypertensives. Conclusions:Vagal inhibition plays an important role in addition to sympathetic activation in alteration of SVI in the genesis of prehypertension, especially in males. Gender and prehypertension status play important role in the causation of SVI. It was suggested that vagal tone of prehypertensives should be maintained at a higher level to prevent their further rise in blood pressure.

Effect of Gender on Sympathovagal Imbalance in Prehypertensives

Although recently the incidence of prehypertension has increased considerably, the pathophysiological mechanisms and the effects of gender in its causation have not yet been fully elucidated. Therefore, in this study body mass index (BMI), waist–hip ratio (WHR), basal heart rate (BHR), blood pressure (BP), rate pressure product (RPP), and spectral indices of heart rate variability (HRV) were reordered and analyzed in normotensive and prehypertensive males and females. It was observed that low frequency–high frequency (LF–HF) ratio, the sensitive indicator of sympathovagal imbalance (SVI), is significantly more (P < .001) in male prehypertensives compared with female prehypertensives. Although SVI in prehypertensives was found to be due to both sympathetic activation and vagal inhibition, contribution of vagal withdrawal was prominent in males. The LF–HF ratio was significantly correlated with BMI, WHR, BHR, BP, and RPP, which was more prominent in male prehypertensives and the degree of correlation was more for WHR and diastolic pressure. It was concluded that vagal inhibition plays an important role in critical alteration of SVI in the genesis of prehypertension, especially in males, and WHR could be a better indicator of SVI in prehypertensives. It was suggested that prehypertensives should improve their vagal tone to restore the sympathovagal homeostasis.

Association of hypertension status and cardiovascular risks with sympathovagal imbalance in first degree relatives of type 2 diabetics

As reports show cardiovascular (CV) risks in first‐degree relatives (FDR) of type 2 diabetics, and autonomic imbalance predisposing to CV risks, in the present study we have assessed the contribution of sympathovagal imbalance (SVI) to CV risks in these subjects.

Effects of Gender on Sympathovagal Imbalance, Prehypertension Status, and Cardiovascular Risks in First-Degree Relatives of Type 2 Diabetics

BACKGROUND Although cardiovascular (CV) risks are reported in first-degree relatives (FDRs) of type 2 diabetics, effects of gender on sympathovagal imbalance (SVI) and CV risks in these subjects have not been investigated. METHODS Body mass index (BMI), blood pressure variability parameters including baroreflex sensitivity (BRS), spectral indices of heart rate variability, autonomic function tests, insulin resistance, lipid profile, inflammatory markers (interleukin 6, high-sensitivity C-reactive protein, tumor necrosis factor α) and oxidative stress (OS) marker were measured and analyzed in control group (without family history of diabetes; 65 women, 60 men) and study group (FDRs of type 2 diabetics; 52 women, 49 men) subjects. RESULTS BMI, heart rate, blood pressure, rate-pressure product, stroke volume, left-ventricular ejection time, cardiac output, total peripheral resistance, homeostatic model of insulin resistance, lipid profile, inflammatory and OS markers, and ratio of low-frequency to high-frequency power of heart rate variability (LF-HF ratio), a sensitive marker of SVI, were significantly increased, and BRS was significantly decreased in study group men compared with women. SVI was more intense in men and was due to concomitant sympathetic activation and vagal inhibition. There was no SVI in control subjects. Multiple regression analysis demonstrated independent contribution of BMI, homeostatic model of insulin resistance, atherogenic index, inflammatory and OS markers, and BRS to LF-HF ratio. Logistic regression analysis demonstrated significant prediction of prehypertension status and rate-pressure product (markers of CV risk) by LF-HF, which was more prominent in men. CONCLUSIONS SVI is more intense in male FDRs of type 2 diabetics, and SVI is associated with increased CV risk due to insulin resistance, dyslipidemia, inflammation, and oxidative stress in these 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.

Gender Difference in the Role of Posterodorsal Amygdala on the Regulation of Food Intake, Adiposity and Immunological Responses in Albino Wistar Rats.

Lesion of posterodorsal amygdala (PDA) has been known to produce hyperphagia and obesity in animal models. However, the influence of gender on food intake (FI), body weight (BW) and immunological parameters following PDA lesion is not yet known. The present work was carried out to study the effect of gender on the regulation of FI, BW and immunological parameters following lesions of PDA in albino Wistar rats. Twenty-four albino Wistar rats were divided equally into 2 groups - PDA group and control group - with 6 male and 6 female rats in each. In the experimental group, bilateral electrolytic lesion of the respective nuclei was performed by stereotaxy and post-lesion parameters were recorded. In the control group, sham lesion was made. Male-female difference in each parameter was determined. Following PDA lesion, FI increased significantly in both male (p < 0.001) and female rats (p < 0.01) but the percentage increase in FI was significantly more in female rats (p < 0.001). BW also increased in both the sexes but the increase in BW was significant only in male rats (p < 0.05). Both male and female rats showed increase in the concentration of cluster of differentiation 4 (CD4), but the significant increase in CD4 concentration (p < 0.01) was seen only in male rats. CD8 concentration increased significantly in male rats (p < 0.05). The liver weight-BW ratio was significantly greater in female rats (p < 0.001) following PDA lesions. Lesion of PDA results in accentuation of FI and BW gain and activation of immunity. There is a gender difference in the inhibitory control of PDA on FI, BW and immunity.

Comparison of the effect of lesions of ventromedial hypothalamus and posterodorsal amygdala on body weight and immunological parameters in albino Wistar rats

Background and Aim: Although hypothalamic and extrahypothalamic areas are known to influence food intake (FI), body weight (BW) and immunity, the exact nature and magnitude of alteration following lesion of these areas have not adequately studied. Therefore, the present study was aimed at comparing the effect of lesions of ventromedial hypothalamus (VMH) and posterodorsal amygdala (PDA) on FI, BW gain and immunological parameters in albino Wistar rats. Methods: A total of 48 albino Wistar rats were taken for the study and were divided equally into VMH group and PDA group with 12 control and 12 experimental rats in each. Bilateral electrolytic lesion of the respective nuclei was performed by stereotaxy. The pre- and post-lesion parameters of both groups were compared. Results: The percentage increase in FI and BW gain was significantly less (P < 0.001) in the experimental rats of PDA group. There was a significant difference in the percentage change in cluster of differentiation 4 (CD4) and CD8 concentration (P < 0.001) in experimental rats of PDA group compared with the experimental rats of VMH group. The percentage decrease in albumin and globulin (P < 0.001) levels and the percentage increase in albumin-globulin ratio (P < 0.001) was significantly less in experimental rats of PDA group. Conclusion: The above-mentioned findings suggest that the role of VMH on feeding is more pronounced than PDA, indicating that VMH has a stronger regulation of adiposity than PDA. Though VMH and PDA are involved in the regulation of immune functions, VMH has a stronger control over immune functions than PDA. Hence, VMH has greater control over adiposity, feeding behavior, and immune functions than PDA.