The effect of the epiphyseal hormone melatonin on the activity of antioxidant enzymes, glutathione peroxidase (GPx), glutathione reductase (GR), and Cu/Zn-superoxide dismutase (Cu/Zn-SOD) was studied in peripheral blood erythrocytes of behaviorally passive and active Wistar rats. Acute emotional stress was modeled by immobilization of animals for1 h with simultaneous electrocutaneous stimulation. Basal activity of antioxidant glutathione enzymes in erythrocytes of behaviorally passive rats was higher than that in active animals. Administration of melatonin (2 mg/kg, intraperitoneally) was accompanied by a decrease in the activity of GPx and GR in erythrocytes from non-stressed passive animals. After experimental stress, passive rats demonstrated a significant increase in the activity of Cu/Zn-SOD and GPx in peripheral blood erythrocytes. The absence of stress-induced changes in functional activity of antioxidant defense enzymes in the blood of behaviorally active animals suggests a relatively constant oxidative status of tissues in these animals under stress conditions. Melatonin administration had little effect on stress-induced changes in functional activity of the erythrocyte antioxidant system in passive rats. Active specimens pretreated with melatonin before stress exposure were characterized by activation of study antioxidant enzymes. Quantitative parameters of the erythrocyte antioxidant defense enzymes did not differ in behaviorally active and passive rats subjected to experimental stress after melatonin injection. Thus, exogenous melatonin abolishes differences in the activity of study antioxidant enzymes in erythrocytes of animals with different behavioral parameters under basal conditions and after experimental stress. In passive rats melatonin mainly reduced the initial tension of oxidative processes. By contrast, administration of this hormone to active specimens is followed by an increase in functional activity of the antioxidant enzyme system under conditions of acute stress.
Issledovali vliianie épifizarnogo gormona melatonina na aktivnost' antioksidantnykh fermentov – glutationperoksidazy (GP), glutationreduktazy (GR) i Cu/Zn-superoksiddismutazy (Cu/Zn-SOD) v éritrotsitakh perifericheskoĭ krovi u povedencheski passivnykh i aktivnykh krys Vistar. V kachestve modeli ostroĭ émotsional'noĭ stressornoĭ nagruzki ispol'zovali 1-chasovuiu immobilizatsiiu zhivotnykh s odnovremennym naneseniem élektrokozhnogo razdrazheniia. Ustanovleno, chto v iskhodnom sostoianii aktivnost' glutationovykh fermentov antioksidantnoĭ zashchity v éritrotsitakh krovi u povedencheski passivnykh krys byla bol'she, chem u aktivnykh osobeĭ. Vnutribriushinnoe vvedenie melatonina v doze 2 mg/kg soprovozhdalos' umen'sheniem aktivnosti GP i GR v éritrotsitakh krovi u nestressirovannykh passivnykh zhivotnykh. Posle éksperimental'nogo stressa u passivnykh krys vyiavleno vyrazhennoe povyshenie aktivnosti Cu/Zn-SOD i GP v éritrotsitakh perifericheskoĭ krovi. Otsutstvie izmeneniĭ funktsional'noĭ aktivnosti fermentativnogo zvena antioksidantnoĭ zashchity krovi u povedencheski aktivnykh zhivotnykh, podvergnutykh stressornoĭ nagruzke, illiustriruet otnositel'noe postoianstvo oksidativnogo statusa tkaneĭ étikh zhivotnykh v usloviiakh stressa. Vvedenie melatonina ne okazyvalo znachimogo vliianiia na vyzvannye stressom izmeneniia funktsional'noĭ aktivnosti antioksidantnoĭ sistemy éritrotsitov krovi u passivnykh krys. U aktivnykh osobeĭ posle stressornoĭ nagruzki na fone predvaritel'nogo vvedeniia melatonina obnaruzhena aktivatsiia vsekh izuchennykh antioksidantnykh fermentov. Kolichestvennye pokazateli fermentativnogo zvena antioksidantnoĭ zashchity éritrotsitov u povedencheski aktivnykh i passivnykh krys, podvergnutykh éksperimental'nomu stressu posle in"ektsii melatonina, prakticheski ne otlichalis'. Takim obrazom, ékzogennyĭ melatonin niveliruet razlichiia v aktivnosti izuchennykh antioksidantnykh fermentov v éritrotsitakh krovi zhivotnykh s raznymi parametrami povedeniia, nabliudaiushchiesia iskhodnom sostoianii i posle éksperimental'nogo stressornogo vozdeĭstviia. Esli u passivnykh krys melatonin sposobstvuet preimushchestvenno snizheniiu iskhodnoĭ napriazhennosti oksidativnogo statusa, to u aktivnykh osobeĭ vvedenie dannogo gormona privodit k povysheniiu funktsional'noĭ aktivnosti fermentativnogo zvena antioksidantnoĭ sistemy v usloviiakh ostroĭ stressornoĭ nagruzki.
Keywords: antioxidant enzymes; blood erythrocytes; emotional stress; melatonin; rats with various behavioral characteristics.