6-Hydroxydopamine lesioning differentially affects α-synuclein mRNA expression in the nucleus accumbens, striatum and substantia nigra of adult rats

The effect of a unilateral 6-hydroxydopamine (6-OHDA) lesion and/or repeated administration of levodopa ( -DOPA) to normal and 6-OHDA-lesioned rats on α-synuclein mRNA expression was investigated by in situ hybridization histochemistry. A 6-OHDA lesion of the nigro-striatal pathway alone, confirmed by the loss of nigral tyrosine hydroxylase mRNA expression, markedly decreased α-synuclein mRNA in the lesioned substantia nigra (SN). In contrast, the levels of α-synuclein mRNA in the denervated striatum and nucleus accumbens were not altered. Chronic administration of -DOPA to normal or 6-OHDA-lesioned rats had no effect on α-synuclein mRNA expression in the SN, striatum or nucleus accumbens. These data confirm that α-synuclein is localized in the nigro-striatal tract but that its gene expression is not regulated by dopamine.