The influence and the mechanism of docosahexaenoic acid (DHA) on visual evoked potentials in experimental parkinson's disease

THE INFLUENCE AND THE MECHAN SM OF DOCOSAHEXAENO C ACID(DHA) ON VISUAL EVOKED POTENTIALS IN EXPERIMENTAL PARKINSON?SDISEASEOzlem KoseDepartment of Physiology, Akdeniz University, Faculty of Medicine, Antalya, Turkey.This study aimed to investigate the effect of Docosahexaenoic acid (DHA) treatment onaltered Visual Evoked Potentials (VEPs) that occur in an experimental mice model of PD andthe related of this effect with antioxidant enzyme activities and lipid peroxidation. Mice wererandomly divided into 4 groups as follows; control (C), DHA-treated (D), Parkinson induced(P), Parkinson induced + DHA-treated (P+D). DHA (36mg/kg/day) was given daily bygavage for 4 weeks. Experimental model of Parkinson?s disease was created by MPTP (1-metil, 4-fenil, 1,2,3,6-tetrahidropiridin, 4x20mg/kg, 12 hour intervals, ip) injections. Motoractivity of mice was evaluated via the ?pole test? and the dopaminergic cell death in SN weredetermined by immunohistochemical analysis of tyrosine hydroxylase (TH) immunopositivecell. VEPs were recorded with sub-dermal needle electrodes placed on the head. Brain andretina superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx) enzymeactivities were determined and the concentration of thiobarbituric acid-reactive substances(TBARS) were measured as an index of oxidative damage. Although DHA treatmentsignificantly diminished the increment of the dopaminergic cell death in the P+D group, it didnot improve decreased motor activity observed in experimental PD. Recorded VEP latencieswere significantly prolonged in the P group and DHA treatment caused a significant decreasein VEP latencies in P+D group. Brain SOD and retina CAT activity were decreased and brainTBARS levels were increased in experimental PD but DHA had no any proofreader effect onthese parameters. The current data shows that DHA treatment improves prolonged VEPlatencies observed in experimental PD mice. The protective effect of DHA treatment on VEPalterations is not related to antioxidant enzyme activities and LP in PD.Key words: Parkinson, MPTP, VEP, DHA, LP, antioxidant enzymes