Neuroprotective effect of vitamin E on the early model of Parkinson's disease in rat: behavioral and histochemical evidence

There is strong evidence that oxidative stress participates in the etiology of Parkinson's disease (PD). We designed this study to investigate the neu roprotective effect of vitamin E in the early model of PD. For this purpose , unilateral intrastriatal 6-hydroxydopamine (12.5 mug/5 mul) lesioned rats were pretreated intramuscularly with D-alpha -tocopheryl acid succinate (2 4 I.U./kg, i.m.) 1 h before and three times per week for 1 month post-surge ry. Apomorphine and amphetamine-induced rotational behavior was measured po stlesion fortnightly. A parallel tyrosine hydroxylase immunoreactivity and wheat germ agglutinin-horse radish peroxidase (WGA-HRP) tract-tracing study was performed to evaluate the vitamin E pretreatment efficacy. Tyrosine hy droxylase-immunohistochemical analyses showed a reduction of 18% in ipsilat eral substantia nigra pars compacta (SNC) cell number of the vitamin E-pret reated lesioned (L+E) group comparing with contralateral side. The cell num ber dropped to 53% in the lesioned (L+V) group. In addition, retrograde-lab eled neurons in ipsilateral SNC were reduced by up to 30% in the L+E group and 65% in the L+V group. Behavioral tests revealed that there are 74% and 68% reductions in contraversive and ipsiversive rotations in the LSE group, respectively, as compared with the L+V group. Therefore repeated intramusc ular administration of vitamin E exerts a rapid protective effect on the ni grostriatal dopaminergic neurons in the early unilateral model of PD. (C) 2 001 Elsevier Science B.V. All rights reserved.