Adiponectin and its role in cardiovascular diseases.

Studies performed during the last decade indicate that adipose tissue is not only a site of triglyceride storage but also an active endocrine organ which secretes many biologically active mediators referred to as "adipokines". In contrast to many adipokines which are overproduced in obese individuals and exert deleterious effects on insulin sensitivity, lipoprotein metabolism and cardiovascular system, such as leptin, tumor necrosis factor-alpha, plasminogen activator inhibitor-1, resistin, etc., adiponectin seems to be a unique adipokine which is produced in lower amounts in obese than in lean subjects and possesses predominantly beneficial activities, i.e. increases insulin sensitivity, stimulates fatty acid oxidation, inhibits inflammatory reaction and induces endothelium-dependent nitric oxide-mediated vasorelaxation. Adiponectin binds two receptors, AdipoR1 and AdipoR2. Adiponectin knockout mice exhibit various manifestations of the metabolic syndrome such as insulin resistance, glucose intolerance, hyperlipidemia, impaired endothelium-dependent vasorelaxation and hypertension, as well as augmented neointima formation after vascular injury. Clinical studies indicate that plasma adiponectin concentration is lower in patients with essential hypertension and ischemic heart disease. Raising endogenous adiponectin level or increasing the sensitivity to this hormone may be a promising therapeutic strategy for patients with metabolic and cardiovascular diseases. Among currently used drugs, thiazolidinediones (peroxisome proliferator activated receptor gamma agonists) are most effective in elevating adiponectin level.

Role of extracellular signal-regulated kinases (ERK) in leptin-induced hypertension.

We investigated if extracellular signal-regulated kinases (ERK) and oxidative stress are involved in the pathogenesis of arterial hypertension induced by chronic leptin administration in the rat. Leptin was administered at a dose of 0.25 mg/kg twice daily s.c. for 4 or 8 days. Blood pressure (BP) was higher in leptin-treated than in control animals from the third day of the experiment. The superoxide dismutase (SOD) mimetic, tempol, normalized BP in leptin-treated rats on days 6, 7 and 8, whereas the ERK inhibitor, PD98059, exerted a hypotensive effect on days 3 through 6. Leptin increased ERK phosphorylation level in renal and aortic tissues more markedly after 4 than after 8 days of treatment. In addition, leptin reduced urinary Na(+) excretion and increased renal Na(+),K(+)-ATPase activity, and these effects were abolished on days 4 and 8 by PD98059 and tempol, respectively. The levels of NO metabolites and cGMP were reduced in animals receiving leptin for 8 days. Markers of oxidative stress (H(2)O(2) and lipid peroxidation products) were elevated to a greater extent after 4 than after 8 days of leptin treatment. In contrast, nitrotyrosine, a marker of protein nitration by peroxynitrite, was higher in animals receiving leptin for 8 days. NADPH oxidase inhibitor, apocynin, prevented leptin's effect on BP, ERK, Na(+),K(+)-ATPase/Na(+) excretion and NO formation at all time points. SOD activity was reduced, whereas glutathione peroxidase (GPx) activity was increased in the group treated with leptin for 8 days. These data indicate that: (1) ERK, activated by oxidative stress, is involved only in the early phase of leptin-induced BP elevation, (2) the later phase of leptin-induced hypertension is characterized by excessive NO inactivation by superoxide, (3) the time-dependent shift from ERK to O(2)(-)-NO dependent mechanism may be associated with reduced SOD/GPx ratio, which favors formation of O(2)(-) instead of H(2)O(2).

Blood lipids profile in obese or overweight patients.

Elevated levels of total and low density lipoprotein (LDL) cholesterol and low levels of high density lipoprotein (HDL) cholesterol are important risk factors for coronary heart disease. Another established predictor of cardiovascular disease is obesity. Obesity and overweight are widespread phenomena and they have reached epidemic proportions in the developed countries, including Poland. Only 30% of people in the Lublin region have normal weight (BMI<25). The aim of this study was to asses the relationship between BMI (body mass index) and blood lipids in the population of 83 people from Aleksandrow commune (64 women and 19 men aged 28-81) who spontaneously applied for medical examination performed as student research. Mean total cholesterol and triglycerides concentrations were higher in obese persons in comparison to normal weight subjects and HDL cholesterol concentration was lower in obese subjects as compared to normal and overweight individuals. Differences in mean concentrations of LDL cholesterol were not significant. A linear correlation between the degree of obesity and plasma level of LDL cholesterol and triglycerides was shown. In conclusion, obesity and overweight are accompanied by unfavourable blood lipids patterns and in a considerable proportion of overweight or obese patients other risk factors for coronary heart disease, such as hypertension, smoking, diabetes or family history of cardiovascular diseases coexist.