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Year : 2013  |  Volume : 15  |  Issue : 67  |  Page : 375--378

The correlation between serum leptin and blood pressure after exposure to noise at work

Muayad S Rahma1, Bassma Ezzat Mustafa1, Ailin Razali2, Niza Shamsuddin3, Osama Y Althunibat4,  
1 Department of Basic Medical Sciences, Kulliyyah of Dentistry, International Islamic University Malaysia, Kuantan, Malaysia
2 Department of Audiology, International Islamic University Malaysia, Kuantan, Malaysia
3 Department of Community Medicine, Kulliyyah of Medicine, International Islamic University Malaysia, Kuantan, Malaysia
4 Department of Biomedical Sciences, Kulliyyah of Science, International Islamic University Malaysia, Kuantan, Malaysia

Correspondence Address:
Muayad S Rahma
Department of the Basic Medical Sciences, Kulliyyah of Dentistry, International Islamic University Malaysia, Kuantan Campus, Jln Sultan Ahmed Shah, Bandar Indhera Mahkota, 25200 Kuantan, Pahang
Malaysia

Abstract

Several epidemiologic studies have reported that exposure to noise is associated with cardiovascular disease. The increased body weight is often associated with metabolic as well as increased blood pressure. The aim of this study is to investigate the correlation between the elevation of blood pressure and serum leptin hormones due to the effects of noise in the work place. A total of 80 volunteer males where included in this study with an age range between of 20 and 45 years, they were divided in two groups equally, the 1 st group were exposed to noise in the workplace while the 2 nd group were not. The individual noise exposure was determined by using a sound level meter. The range of noise was 80-100 dBA. Body Mass Index was also taken for each individual by a standard measure, blood pressure was measured by OMRON sphygmomanometer and serum leptin was measured through venous blood sample analysis enzyme linked immunosorbent assay. Spearman rank order correlation was used to examine the correlations between Blood pressure value (Systolic, Diastolic) and Leptin. All the relationships between parameters showed a positive correlation. Systolic and diastolic blood pressure values had a significant correlation to leptin hormone level in comparison to the control. There was a significant relation between leptin and blood pressure. leptin effects on the sympathetic nervous system may provide a partial explanation. Therefore, Leptin might have diverse cardiovascular actions.



How to cite this article:
Rahma MS, Mustafa BE, Razali A, Shamsuddin N, Althunibat OY. The correlation between serum leptin and blood pressure after exposure to noise at work.Noise Health 2013;15:375-378


How to cite this URL:
Rahma MS, Mustafa BE, Razali A, Shamsuddin N, Althunibat OY. The correlation between serum leptin and blood pressure after exposure to noise at work. Noise Health [serial online] 2013 [cited 2021 Jul 24 ];15:375-378
Available from: https://www.noiseandhealth.org/text.asp?2013/15/67/375/121223


Full Text

 Introduction



Several epidemiologic studies have reported that exposure to noise is associated with cardiovascular disease, including myocardial infarction [1] and coronary heart disease. [2],[3] This association may be because noise exposure enhances the development of hypertension. Many field studies have demonstrated that high-level noise exposure [>85 A-weighted decibels (dBA)] may cause the transient elevation of blood pressure. [4]

Laboratory studies have consistently shown that acute noise exposure, even at moderate levels of around 80 dBA, has cardiovascular and autonomic effects that are manifested by increased vascular resistance heart rate, blood pressure [4] and stress hormones. [5]

Regarding hormonal studies after noise exposure, noise acts like a stressor and elevates the secretion of the corticosterone and leptin. [6] This is reflected by fight-flight reaction, characterized by an increase in adrenaline, noradrenalin and increased cortisol. Extreme intense acute noise exposure near the threshold of pain causes an increase in the release of cortisol from the suprarenal cortex; however, acute noise exposure with levels between 90 and 100 dBA caused an increase of catecholamine and leptin. [7]

Anxiety is a part of the response to stress. Stress and physiological and behavioral symptoms of anxiety are inter-related. The aim of this study is to investigate the effect of noise on serum leptin hormone level as well as the correlation with blood pressure changes after occupational noise exposure in male workers.

 Methods



A total of 80 male volunteers with an age range between 20 and 45 years were divided into two groups, 40 of them were exposed to daily noise in their workplace (the case) while the other 40 were not (control). We determine individual noise exposure by using a sound level meter (Quest Technology, 2900 Advanced Integrating Sound level Mete) to measure the intensity of the noise in the working area. The noise average was 85 dBA in a whole day so we used the range of noise 80-100 dBA for our study. We determined the Body Mass Index (BMI) by standard measures of 23 ± 1.98. We measured the central blood pressure using OMRON model M7, sphygmomanometer, in addition to that we measured serum leptin by taking blood samples from the study subjects. The measurement of serum leptin will be by collection of about 5 ml of venous blood from each subjects then quantitative measurement of leptin in serum was performed using a leptin enzyme immunoassay or enzyme-linked immunosorbent assay (ELISA) kit.

Determination of serum Leptin

The IBL ELISA Kit is based on the competition principle and microtiterplate separation. An unknown amount of leptin present in the sample and a fixed amount of Leptin conjugate immobilized onto the wells, compete for the binding sites of a polyclonal antiserum.

In a second step an enzyme complex binds to the antiserum; the unbound enzyme complex is then washed off. Having added the substrate solution the concentration of leptin in the sample is inversely proportional to the optical density measured. Any microwell reader capable of determining the optical density measured. Any microwell reader capable of determining the absorbance at 450-10 nm may be used, the leptin value of each serum sample is obtained as follows;

Using linear - linear or semi log graph paper, construct a standard curve by plotting the average absorbance of each reference standard against its corresponding concentration in ng/ml. for construction of the standard curve we recommend a four parameter logistic function.Use the average absorbance of each serum sample to determine the corresponding leptin value by simple interpolation from this standard curve, multiplying by the initial sample dilution.The IBL leptin ELISA was compared with another commercially available RIA assay, their correlation coefficient is r = 0.95.

Determination of blood pressure

Office blood pressure measurement involves three measurements of systolic (SBP) and diastolic blood pressure (DBP), using the average of the last two, with a validated OMRON model M7 sphygmomanometer (Omron Health Care, Kyoto, Japan), by following the recommendations of the European Society of Hypertension. [8] Pulse pressure was estimated with the mean values of the second and third measurements.

Determination of BMI

BMI categorized into four groups according to World Health Organization (WHO) guidelines ( http://apps.who.int/bmi/index.jsp?introPage=intro_3.html ): (a) Underweight (≤18.5 kg/m 2 ), (b) Normal weight (18.5-24.9 kg/m 2 ), (c) Overweight (25.0-29.9 kg/m2), and (d) Obese (≥30.0 kg/m 2 ). We anticipated all the included studies to be according to WHO BMI classification guidelines. Therefore, we used the formula to determine the BMI which is equal to the individual's body mass divided by the square the height. [9]

Statistical analysis

The Shapiro-Wilk test has been used to check the normality of study data. Spearman rank order correlation was used to determine the relationship between the parameters and the correlation is significant of value < 0.05. All statistical analysis was performed using Statistical Package for the Social Sciences (SPSS) version 17 computer software.

 Results



The study's data is non-normal distributed due to a significant value of Shapiro-Wilk. Therefore, we used Median, Minimum, and Maximum for data description [Table 1]. Spearman rank order correlation was used to examine the correlations between blood pressure value (Systolic, Diastolicand Leptin. All the relationships between parameters are positive correlation. Systolic values have a significant correlation with leptin hormone level as compared to the control [Figure 1] and [Figure 2]. In same case diastolic values have a significant correlation with leptin level as compared to control group [Figure 3] and [Figure 4].{Table 1}{Figure 1}{Figure 2}{Figure 3}{Figure 4}

 Discussion



In this study, correlation analysis has been performed, there was a positive correlation between SBP and DBP and leptin hormone level. Data from animal studies indicate an association between leptin and hypertension, [10] Some human studies have reported significantly higher leptin levels in essential hypertensive patients than in controls, as well as a significant correlation between leptin levels and blood pressure. [11] These results were not confirmed by Kokot et al. 1999, [12] who found no difference in plasma leptin levels between hypertensive patients and controls. In another study, Hirose et al. 2007, [13] reported a correlation between mean blood pressure and leptin also after adjustment for age and BMI. However, no association was found between the 24-h DBP and BMI-adjusted leptin by Narkiewicz et al. 1999. [14] Suteret et al., in 1998 [15] reported a significant relation between SBP and plasma leptin levels in hypertensive women but not in hypertensive men. On the other hand, Kennedy et al. 1997, [16] demonstrated a relationship between elevated SBP and DSP and plasma leptin levels in hypertensive men only. Obese patients are frequently characterized by sympathetic hyperactivity and higher plasma levels of adrenaline and noradrenaline. [17] One factor that may contribute to an increase in sympathetic nervous activity is plasma leptin. Chronic leptin infusion has been shown to increase heart rate and blood pressure in animal models [18],[19] through stimulation of sympathetic nervous system activity. [20] An intracerebroventricular injection of leptin increases the activity of both lumbar and renal sympathetic nerve activity and reduces arterial blood flow to skeletal muscle. As leptin penetrates the blood-cerebrospinal fluid barrier by active transport, it seems likely that leptin activates sympathetic nerve activity in the central nervous system. The link between plasma leptin and the autonomic nervous system is strengthened by evidence of a direct relationship between muscle sympathetic nerve activity and plasma leptin concentrations. [21],[22],[23] Moreover, a direct relationship between plasma leptin and heart rate has been observed in hypertensive patients. [14] This relationship seems to be independent of body mass index, plasma insulin, blood pressure, smoking, and physical activity, suggesting that leptin may influence cardiovascular neuronal control also in human.

 Conclusions



There is significant relation between leptin and blood pressure, leptin effects on the sympathetic nervous system may provide a partial explanation. Leptin has diverse cardiovascular actions, although sympatho activation is probably the most important. The concept of selective leptin resistance may explain how leptin could contribute to hypertension, despite the loss of its metabolic effects. Increasing knowledge of the mechanisms and sites of leptin resistance should provide new insights to this relation.

 Acknowledgements



We would like to thank and appreciate the research management center (RMC) of the International Islamic University for the assistance and support in order to finish this study, as well as we would like to thank Assistant Professor Dr Omer Q. B. Al-Lela who provided the statistical advices.

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