Leptin, adiponectin, and heart rate variability among police officers

The sex-dependent response to psychosocial stress and ischaemic heart disease

Stress is an important risk factor for modern chronic diseases, with distinct influences in males and females. The sex specificity of the mammalian stress response contributes to the sex-dependent development and impacts of coronary artery disease (CAD). Compared to men, women appear to have greater susceptibility to chronic forms of psychosocial stress, extending beyond an increased incidence of mood disorders to include a 2- to 4-fold higher risk of stress-dependent myocardial infarction in women, and up to 10-fold higher risk of Takotsubo syndrome-a stress-dependent coronary-myocardial disorder most prevalent in post-menopausal women. Sex differences arise at all levels of the stress response: from initial perception of stress to behavioural, cognitive, and affective responses and longer-term disease outcomes. These fundamental differences involve interactions between chromosomal and gonadal determinants, (mal)adaptive epigenetic modulation across the lifespan (particularly in early life), and the extrinsic influences of socio-cultural, economic, and environmental factors. Pre-clinical investigations of biological mechanisms support distinct early life programming and a heightened corticolimbic-noradrenaline-neuroinflammatory reactivity in females vs. males, among implicated determinants of the chronic stress response. Unravelling the intrinsic molecular, cellular and systems biological basis of these differences, and their interactions with external lifestyle/socio-cultural determinants, can guide preventative and therapeutic strategies to better target coronary heart disease in a tailored sex-specific manner.

Alteration of serum leptin and LEP/LEPR promoter methylation in Prader-Willi syndrome

Prader-Willi syndrome (PWS) is a rare neurodevelopmental disorder based on a loss of paternally expressed but maternally imprinted genes in chromosome region 15q11-13. PWS individuals typically show insatiable appetite with subsequent obesity representing the major mortality factor unless food intake is inhibited. The neurobiological basis of PWS-typical hyperphagia has remained poorly understood. Many PWS-typical abnormalities are based on hypothalamic dysregulation, a region in which hunger and satiety are hormonally regulated, with the hormone leptin being a main long-term regulator of satiety. Previous studies in PWS have inconsistently shown leptin alterations solely in early childhood, without investigating the leptin system on an epigenetic level. The present study investigates serum leptin levels (S-leptin) and DNA methylation of the leptin (LEP) and leptin receptor gene (LEPR) promoter in 24 individuals with PWS compared to 13 healthy controls matched for sex, age, and body mass index (BMI) and relates the results to the extent of hyperphagia in PWS. S-Leptin levels were obtained by Enzyme-linked Immunosorbent Assay. LEP/LEPR-promoter DNA methylation was assessed by bisulfite-sequencing, hyperphagia by Hyperphagia Questionnaire for Clinical Trials (HQ-CT). PWS and control groups differed significantly in S-leptin levels with higher S-leptin in PWS. Methylation analysis showed significant differences in mean promoter methylation rate both for LEP and LEPR with a lower methylation rate in PWS. LEPR, but not LEP methylation correlated significantly with S-leptin levels. S-leptin and both LEP and LEPR methylation did not correlate with HQ-CT scores in PWS. The present study is the first to show significantly elevated S-leptin levels in an adult PWS cohort combined with an altered, downregulated LEP and LEPR promoter methylation status compared to sex-, age- and BMI-matched controls. Analogous to previous studies, no link to the behavioral dimension could be drawn. Overall, the results suggest an increased leptin dysregulation in PWS, whereby the findings partly mirror those seen in non-syndromic obesity.

Effects of Aerobic Exercise on the Serum Leptin Level and Heart Rate Variability in the Obese Girl Children

Objective

The present study examined the effects of a 16-week aerobic exercise (AE) on the serum leptin level and heart rate variability (time domain and frequency domain) in the obese girl children and correlation coefficients of changes between the serum leptin level and heart rate variability after a 16-week AE intervention.

Methods

36 participants were randomly assigned to either aerobic exercise (AE, n = 18) or obese group (n = 18). The obese girl children in the AE group conducted a 16-week (4 times per week and 60 min per time) exercise protocols, and the obese group did not perform regular physical training during 16 weeks of study. Then, the serum leptin level and HRV (time domain and frequency domain) were measured in all subjects before and after AE intervention.

Results

(1) After 16-week AE intervention, compared with pre-exercise, LF/HF decreased (P < 0.05), HF, SDNN, and RMSSD significantly increased (P < 0.05 and P < 0.01), and there was no significant difference in LF (P > 0.05) in the AE group. Nevertheless, there was no significant change before and after the test in the serum leptin level and HRV of the obese group (P > 0.05, respectively). (2) After 16-week AE intervention, compared with the obese group, SDNN and HF significantly increased (P < 0.05, respectively), LF/HF significantly decreased (P < 0.05) in the AE group, but there was no significant difference in RMSSD and LF between the obese group and AE group. (3) The reduction variables of the serum leptin level before and after the AE intervention are positively correlated with the reduction in the LF/HF (r = 0.478, P < 0.05) and negatively correlated with the increasing in the RMSSD (r = -0.482, P < 0.05). But there is no significant association between the reduction in the serum leptin level and the change of LF, HF, and SDNN (P > 0.05, respectively).

Conclusion

16-week AE significantly reduced the serum leptin level and improved cardiac autonomic function in the obese girl children. Moreover, the reduction in the serum leptin level was associated with the increase in parasympathetic activation and improved sympathetic-vagus balance after AE intervention. More research is needed to see whether the effect of exercise on leptin levels in obese girl children can reduce the risk of cardiovascular disease in adulthood.

Aerobic fitness influences cardiac autonomic modulation in police officers regardless of specific duties

PURPOSE

This study assesses whether the specific duties of a police officer or aerobic fitness influences blood pressure (BP) and cardiac autonomic modulation.

METHOD

Police officers (n = 161) were divided into administrative and operational (34.72 ± 5.98 vs. 33.95 ± 5.61 years old) groups, and subsequently divided into lower and higher aerobic fitness (35.49 ± 4.32 vs. 45.39 ± 13.10 mL·kg-1·min-1).

RESULTS

Higher SBP (125 ± 10 vs. 121 ± 10 mmHg; P = 0.02) and aerobic fitness (42.10 ± 5.57 vs. 38.51 ± 6.67 mL·kg-1·min-1; P < 0.01) were observed in the operational group. On the other hand, lower obesity indicators and higher heart rate variability (HRV) indices (SD1: 26.67 ± 14.19 vs. 20.98 ± 9.12; SD2: 54.04 ± 19.81 vs. 47.32 ± 18.85; RMSSD: 36.50 ± 18.78 vs. 29.90 ± 12.51; SDNN: 42.80 ± 16.05 vs. 36.85 ± 14.23 ms; pNN50: 17.32 ± 17.54 vs. 10.60 ± 10.77 %) were observed in the higher aerobic fitness group (P ≤ 0.05).

CONCLUSION

In summary, although the operational occupation had shown a negative influence on SBP, the HRV was not impaired in police officers. Additionally, aerobic fitness was related to differences in obesity indicators and HRV regardless of police duties. Our findings encourage the inclusion of BP and HRV measurements in routine health checks to screen for early hypertension and autonomic dysfunction.

Correlation of C1q/TNF-Related Protein-3 with Cardiac Autonomic Tone and Metabolic Parameters in Obesity

OBJECTIVES

The current study aimed at investigating the correlation of circulating levels of serum C1q/TNF-related protein-3 (CTRP3) with cardiac autonomic functions and metabolic parameters in obesity.

METHODS

Thirty drug naïve subjects newly diagnosed with obesity and body mass index (BMI) 25 - 35 kg/m² of both genders aged 19 - 40 years, with no associated comorbidity were recruited as cases. Same number of age, gender and socioeconomic status matched subjects with BMI 19 - 23 kg/m² were taken as controls. Autonomic function test results including heart rate variability (HRV) were recorded in both groups. Serum metabolic parameters -CTRP3, leptin, adiponectin, insulin, blood glucose, glycated hemoglobin (HbA1c), aspartate aminotransferase (AST), alanine aminotransferase (ALT), total cholesterol, low-density lipoprotein (LDL)-cholesterol, high-density lipoprotein (HDL)-cholesterol, and triglycerides were also determined and compared between the groups.

RESULTS

Significantly lower circulating levels of CTRP3 (P ≤ 0.001) and adiponectin (P = 0.025), and significantly higher mean of BMI (P < 0.001), fasting blood glucose (P < 0.001), LDL-cholesterol (P < 0.05), serum triglycerides (P < 0.001), insulin (P = 0.003), HOMA-IR (homeostasis model assessment of insulin resistance) (P < 0.001), and leptin (P = 0.043) were observed in the group with obesity compared to the controls. CTRP3 levels inversely correlated with serum triglyceride (r = -0.09, P < 0.001), atherogenic index (r = -0.37, P = 0.04), leptin (r = -0.39, P = 0.02), and positively with adiponectin (r = 0.42, P = 0.02) in the group with obesity. Significant reduction in the results of parasympathetic autonomic function tests (pNN50, RMSSD, excitation: inhibition (E:I) ratio, 30:15 ratio, and Valsalva ratio) and an increase in sympathovagal balance (low frequency to high frequency (LF:HF) ratio) was also observed (P < 0.05). CTRP3 levels were also positively correlated with parasympathetic indices (pNN50: r = 0.17, P < 0.05); 30:15 ratio: (r = 0.62, P < 0.01), and inversely correlated with LF: HF ratio (r = -0.35, P < 0.01) in the group with obesity.

CONCLUSIONS

Higher circulating levels of CTRP3 promoted a favorable autonomic and metabolic profile in obesity. Hence, CTRP3 may be considered as a potential novel biomarker to facilitate the prognosis of obesity and its comorbidities.

Physical Activity and Heart Rate Variability in Adolescents with Abdominal Obesity

Physical activity is a protective factor for autonomic dysfunction. However, whether this occurs in adolescents with abdominal obesity is still unclear. Thus, the aim of this study was to analyze the association between physical activity and heart rate variability (HRV) in adolescents with and without abdominal obesity. This cross-sectional study included 1152 boys (age: 17 ± 1 years). HRV measures of time (root mean square of the squared differences between adjacent normal RR intervals-RMSSD and the percentage of adjacent intervals over 50 ms-PNN50) and frequency domains (balance sympathetic-vagal-LF/HF) were evaluated, as well as total physical activity, commuting physical activity, leisure-time physical activity, and abdominal obesity. All physical activity domains were associated with better RMSSD, PNN50, and LF/HF in normal weight adolescents (p < 0.05), whereas in adolescents with abdominal obesity only leisure-time physical activity was associated with better PNN50 (b = 0.174, p = 0.035) independent of age, period of the day, body mass index, and blood pressure. In conclusion, higher leisure-time physical activity, but not total and commuting physical activity levels, was associated with improved HRV in adolescents with abdominal obesity.

Adiponectin, biomarkers of inflammation and changes in cardiac autonomic function: Whitehall II study

BACKGROUND

Biomarkers of inflammation and adiponectin are associated with cardiovascular autonomic neuropathy (CAN) in cross-sectional studies, but prospective data are scarce. This study aimed to assess the associations of biomarkers of subclinical inflammation and adiponectin with subsequent changes in heart rate (HR) and heart rate variability (HRV) in non-diabetic and diabetic individuals.

METHODS

Data are based on up to 25,050 person-examinations for 8469 study participants of the Whitehall II cohort study. Measures of CAN included HR and several HRV indices. Associations between baseline serum levels of high-sensitivity C-reactive protein (hsCRP), interleukin (IL)-6, IL-1 receptor antagonist (IL-1Ra) and adiponectin and 5-year changes in HR and six HRV indices were estimated using mixed-effects models adjusting for age, sex, ethnicity, body mass index (BMI), metabolic covariates and medication. A modifying effect of diabetes was tested.

RESULTS

Higher levels of IL-1Ra were associated with higher increases in HR. Additional associations with measures of HRV were observed for hsCRP, IL-6 and IL-1Ra, but these associations were explained by BMI and other confounders. Associations between adiponectin, HR and HRV differed depending on diabetes status. Higher adiponectin levels were associated with more pronounced decreases in HR and increases in three measures of HRV reflecting both sympathetic and vagal activity, but these findings were limited to individuals with type 2 diabetes.

CONCLUSIONS

Higher IL-1Ra levels appeared as novel risk marker for increases in HR. Higher adiponectin levels were associated with a more favourable development of cardiovascular autonomic function in individuals with type 2 diabetes independently of multiple confounders.

Longitudinal Associations of Leptin and Adiponectin with Heart Rate Variability in Children

For early prevention of cardiovascular disease, early detection and risk factor insights are necessary. The autonomic balance reflects cardiovascular risk and can be measured by heart rate variability (HRV). Therefore, our purpose is to examine associations between HRV and the energy-related biomarkers leptin and adiponectin in children. Participants of this study were Belgian children recruited for the longitudinal ChiBS study (year 2010-2012). HRV was measured and fasting blood samples were taken in 249 children at baseline (4.4-11.0 y) and 223 children at follow-up (6.7-12.2 y). Cross-sectional and longitudinal linear regression analyses were separated by sex and adjusted for age, socio-economic status, body fat%, negative emotions, puberty, and mean heart rate. Leptin was a negative cross-sectional and longitudinal predictor of parasympathetic activity in boys; while leptin in girls was cross-sectionally associated with higher LF and LF/HF suggesting sympathetic predominance. Adiponectin was a negative cross-sectional and longitudinal predictor of parasympathetic activity in boys; but when adjusting for mean heart rate, this effect disappeared and adiponectin was a positive cross-sectional and longitudinal predictor of parasympathetic activity in girls. These results stress the importance of considering sex differences and adjustment for heart rate in testing HRV predictors. Leptin seemed disadvantageous for the autonomic balance, while adiponectin seemed advantageous for the autonomic balance in girls only. More research is needed to see whether leptin and adiponectin are interesting in cardiovascular screening/prevention or in determining the cardiovascular gain during weight loss follow-up.

Association of glucose homeostasis measures with heart rate variability among Hispanic/Latino adults without diabetes: the Hispanic Community Health Study/Study of Latinos (HCHS/SOL)

BACKGROUND

Reduced heart rate variability (HRV), a measure of cardiac autonomic function, is associated with an increased risk of cardiovascular disease (CVD) and mortality. Glucose homeostasis measures are associated with reduced cardiac autonomic function among those with diabetes, but inconsistent associations have been reported among those without diabetes. This study aimed to examine the association of glucose homeostasis measures with cardiac autonomic function among diverse Hispanic/Latino adults without diabetes.

METHODS

The Hispanic community Health Study/Study of Latinos (HCHS/SOL; 2008-2011) used two-stage area probability sampling of households to enroll 16,415 self-identified Hispanics/Latinos aged 18-74 years from four USA communities. Resting, standard 12-lead electrocardiogram recordings were used to estimate the following ultrashort-term measures of HRV: RR interval (RR), standard deviation of all normal to normal RR (SDNN) and root mean square of successive differences in RR intervals (RMSSD). Multivariable regression analysis was used to estimate associations between glucose homeostasis measures with HRV using data from 11,994 adults without diabetes (mean age 39 years; 52 % women).

RESULTS

Higher fasting glucose was associated with lower RR, SDNN, and RMSSD. Fasting insulin and the homeostasis model assessment of insulin resistance was negatively associated with RR, SDNN, and RMSSD, and the association was stronger among men compared with women. RMSSD was, on average, 26 % lower in men with higher fasting insulin and 29 % lower in men with lower insulin resistance; for women, the corresponding estimates were smaller at 4 and 9 %, respectively. Higher glycated hemoglobin was associated with lower RR, SDNN, and RMSSD in those with abdominal adiposity, defined by sex-specific cut-points for waist circumference, after adjusting for demographics and medication use. There were no associations between glycated hemoglobin and HRV measures among those without abdominal adiposity.

CONCLUSIONS

Impairment in glucose homeostasis was associated with lower HRV in Hispanic/Latino adults without diabetes, most prominently in men and individuals with abdominal adiposity. These results suggest that reduced cardiac autonomic function is associated with metabolic impairments before onset of overt diabetes in certain subgroups, offering clues for the pathophysiologic processes involved as well as opportunity for identification of those at high risk before autonomic control is manifestly impaired.

Plasma leptin level is associated with cardiac autonomic dysfunction in patients with type 2 diabetes: HSCAA study

Background

It has been shown that visceral fat accumulation is associated with autonomic dysfunction, though the precise mechanism remains unclear. A recent basic study found that leptin can directly modulate autonomic function through the dorsomedial hypothalamus in relation to obesity. Here, we investigated the mutual relationships among plasma leptin, visceral fat accumulation, and cardiac autonomic dysfunction in patients with type 2 diabetes.

Methods

This cross-sectional study included 100 diabetic patients, and 100 age- and gender-matched non-diabetic patients with cardiovascular risk factors. Plasma leptin and soluble leptin receptor levels, visceral fat area (VFA), and heart rate variability (HRV) were determined in addition to classical cardiovascular risk factors.

Results

In the type 2 diabetic patients, VFA was significantly (p < 0.05) and inversely associated with HRV parameters (SDNN: r = −0.243; SDANN5: r = −0.238), while the plasma level of leptin, but not soluble leptin receptor, was also significantly (p < 0.05) and inversely associated with HRV parameters (SDNN: r = −0.243; SDANN5: r = −0.231). Multiple regression analysis showed that plasma leptin was significantly associated with SDNN and SDANN5 independent of other factors, including age, gender, presence of hypertension and dyslipidemia, duration of diabetes, HbA1c, and eGFR. Furthermore, the relationship of leptin with SDNN and SDANN5 (β = −0.279 and −0.254, respectively) remained significant (p < 0.05) after adjustment for VFA. In patients without diabetes, no significant associations were observed between leptin and any of the HRV parameters.

Conclusions

Hyperleptinemia may be involved in cardiac autonomic dysfunction in patients with type 2 diabetes and visceral obesity.