The action of prolyl-leucyl-glycinamide (PLG) on the nigrostriatal pathway of the rat

Abstract

In order to study the nigrostriatal pathway, we obtained the rotatory behavior model in male Wistar rats by electrolytic lesion of the left lateral hypothalamic region. Animals thus lesioned displayed rotations toward the same side of lesion when apomorphine was administered, a result in disagreement with what has been obtained in the model with 6-hydroxydopamine lesion. The administration of PLG alone was not followed by rotatory behavior but when the compound was administered in low doses (0.25 to 1mg/kg) simultaneously with apomorphine to animals previously submitted to REM sleep deprivation, a significant increase in the number of rotations was observed in comparison with controls and groups receiving higher doses of PLG. These results indicate that PLG may act as, a modulator on dopamine receptors in the striatum.

No intuito de estudar a via nigroestriatal, produzimos uma lesão na região hipotalâmica lateral de ratos Wistar. Os animais passavam a apresentar comportamento rotatório para o mesmo lado da lesão. A administração isolada do PLG não induziu o comportamento rotatório. Entretanto, com doses baixas do composto, concomitantemente à administração de apomorfina em animais previamente submetidos à privação de sono REM, observou-se aumento no número de rotações auando comparado ao grupo controle e aos grupos aue receberam doses altas de PLG. Estes achados sugerem que o PLG age como um modulador sobre os receptores dopaminérgicos do estriado.