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[Effect of melatonin on lipid peroxidation in the blood of rats with various behavioral characteristics during acute emotional stress].

This work was designed to study the effect of melatonin on lipid peroxidation in the peripheral blood of behaviorally passive and active Wistar rats. Immobilization of rats with simultaneous electrocutaneous stimulation (1 h) served as a model of acute stress. After intraperitoneal injection of melatonin (2 mg/kg) the intensity of lipid peroxidation in the blood plasma remained practically unchanged in passive specimens, but increased in active animals. Stress exposure was followed by specific variations in free radical processes in the blood (passive rats, inhibition; active specimens, no changes). Administration of melatonin contributed to a decrease in the intensity of lipid peroxidation in the blood of stressed rats (as compared to control specimens receiving this neurohormone). Therefore, the effect of melatonin on free radical processes depends on the initial behavioral characteristics and physiological state of animals. These data illustrate the importance of an individual approach to studying the systemic mechanisms for organization of functions in mammals. Key words: melatonin, emotional stress, lipid peroxidation, blood plasma, rats with various behavioral characteristics.