EFFECTS OF Tyr-W-MIF-1 AND Tyr-K-MIF-1 ON LIPID PEROXIDATION AND ANTIOXIDANT ENZYME ACTIVITIES IN RAT BRAIN AFTER THREE STRESS FACTORS

Stress influences neuroendocrine, autonomic, and immune regulations. The exact underlying mechanisms are not yet fully understood, but accumulating evidence has implied that the production of reactive oxygen species plays a critical role in these processes. Different stress models have different degrees of influences on enzymatic and non-enzymatic antioxidant defense systems, protein oxidation and lipid peroxidation in the brain. One of the mechanisms known to play a part in the response of an organism to stress is activation of the endogenous opioid system. Endomorphins provide protection against free radical-induced neurodegenerative disorders. Tyr-W-MIF-1 and Tyr-K-MIF-1 are neuropeptides/neuromodulators with opioid like actions, which belong to Tyr-MIF-1 family of peptides. There are no data about effects of Tyr-W-MIF-1 and Tyr-K-MIF-1 on lipid peroxidation or on antioxidant markers such as superoxide dismutase and catalase. The aim of our study was to investigate the effects of Tyr-W-MIF-1 and Tyr-K-MIF-1 on lipid peroxidation and antioxidant enzyme activities in rat brain after immobilisation, cold and heat stress. The obtained results demonstrate that both peptides exert certain brain protective effects against prooxidative action of some kind of physical stress especially in immobilisation and cold stress.