EN
It has been proposed that in the Parkinson’s disease exo- or endogenous N-methyl-compounds like 1-methylnicotinamide (MNA) could be accumulated by dopaminergic neurons and induces neurotoxic effects, as happens with MPP+. The aim of this study was to test this hypothesis by comparing direct effects of MPP+ or MNA application into the striatum of 7 day old rat pups and to the substantia nigra (SN) of the adult rats. Microinjections of tested substances in doses: MPP+ (20 and 100 μg) and MNA (20, 40, 80 μg), were made unilaterally. Effects of MNA and MPP+ on pups’ striatum were evaluated by TTC staining and the lesion volume was calculated using the ImageJ program. In the SN of adult rats alterations in the level of tyrosine hydroxylase (TH) immunostaining were examined at the 5th day after MPP+ or MNA injection, utilizing antibody specifi c to TH. Moreover the coronal sections (20 μm thick) of the SN were examined to evaluate MNA- or MPP+-induced glial activation with the glia-specifi c lectin. Using these methods we did not observe any toxic effect of MNA. MPP+ induced statistically signifi cant damages in the striatum of rat pups, whereas there was no lesion after MNA injection. Also in the SN of adult rats MPP+ caused 50% loss of TH-positive neurons and doubled the number of activated glial cells, while MNA injection had no visible effect. Summing up, present data did not demonstrate any toxic effects of MNA on dopaminergic neurons in the rat brain in vivo.