[Metabolic syndrome and melatonin].

Metabolic syndrome (MS) is characterized by the following symptoms: obesity, AH, dyslipidemia, insulin resistance. Pathophysiologically, MS is underlain by disorders of many biochemical and physiological processes, such as elevated levels of low density lipoproteins, hyperstimulation of pancreatic b-cells, increased insulin secretion, substitution of lipid metabolism for carbohydrate one, overgrowth of adipose tissue, excess production of adiponectin, leptin and other signal molecules and a rise in their local intravascular concentration, weight gain. Endogenous and exogenous melatonin inhibits these pathophysiological mechanisms, normalizes metabolism, equilibrates insulin secretion, prevents pancreatic hyperfunction, phosphorylates insulin receptors, inactivates active oxygen and nitrogen species including those produced in LDLP metabolism. Melatonin has specific MT1 and MT2 receptors localized in all body cells. Due to this, it exerts combined preventive action in patients with MS. Recently, melatonin has been reported to have therapeutic effect in MS; it may be recommended to treat this condition.

[Determination of melatonin in biological fluids].

The review considers main approaches to solving the problem in the quantification of melatonin and describes physicochemical and biological methods for melatonin determination in biological fluids (saliva, urine, plasma) and tissues. The impetus to writing this paper came from the considerably growing interest of the scientific community in melatonin and the in-depth studies of its physiological role, which had revealed a diversity of its previously unknown most important functions and confirmed its presence in many compartments of the body. Due to the specificity of its molecular structure and low concentration, melatonin remains invisible for many conventional analyses. The way out may be combination detection that involves the benefits of a few procedures and that has emerged at the interface of various sciences.