The assessment of correlations between serum leptin concentration, blood pressure values and sympathetic nervous system activity in patients with metabolic syndrome and essential hypertension

Background Leptin is one of the cytokines secreted by adipocytes and plays an important role in the regulation of food intake, thermogenesis and different metabolic processes and also blood pressure values. The aim of the study was to estimate the relationship between plasma leptin concentration and sympathetic nervous system activity and blood pressure values in patients with metabolic syndrome and essential hypertension. Material and methods The study group consisted of 68 patients divided into 3 subgroups: 1. subjects with metabolic syndrome and hypertension (n = 31), 2. subjects with essential hypertension, without obesity (n = 22), 3. control group (n = 15) included normotensive, non-obese individuals in comparable age. In all subjects fasting leptin concentration was measured using RIA test. Systolic and diastolic blood pressure (SBP, DBP) and heart rate (HR) as a sympathetic nervous system activity indicator were assessed. Basic anthropometric and biochemical parameters were also estimated to determine the group assignment. Results Mean plasma leptin concentrations in 3 groups were: 1 - 22.86 +/- 10.52 ng/ml; 2 - 16.44 +/- 11.02 ng/ml; 3 - 11.18 +/- 5.87 ng/ml respectively. Significant differences were found in group 1 vs. 2 and 3 and 2 vs. 3. Significantly higher leptin levels were characteristic for women in all groups. Mean SBP and DBP were: 1 - 164.7 +/- 2.0 mm Hg and 91.3 +/- 7.8 mm Hg, 2 - 158.1 +/- 2.4 mm Hg and 89.3 +/- 6.7 mm Hg, 3 - 130.6 +/- 2.8 mm Hg and 76.1 +/- 5.6 mm Hg. It was claimed that there were significant differences between groups: 1 vs. 3 and 2 vs. 3. Mean HR in 3 groups were: 1 - 78.7 +/- 10.3 beets/min, 2 - 80.9 +/- 11.0 beets/min, 3 - 71.2 +/- 5.6 beets/min respectively. Significant differences were found in group: 1 vs. 3 and 2 vs. 3. In both groups: with metabolic syndrome and essential hypertension a significant positive correlations were found between leptinemia and mean SBP and mean HR. Conclusions: 1. Patients with metabolic syndrome are characterized by the higest lepin levels. 2. Positive correlations between leptin and HR and SBP in both study groups suggest that leptin may contribute to an essential hypertension development through sympathetic nervous system activity.