l-Dopa stimulates c- fos expression in dopamine denervated striatum by combined activation of D-1 and D-2 receptors

Administration of l-dopa to unilaterally 6-hydroxydopamine-lesioned rats, activates the early gene c- fos in the lesioned caudate-putamen. D-1 receptor blockade by SCH 23390, prevented l-dopa-induced Fos-like immunoreactivity in the whole caudate-putamen, while D-2 receptor blockade by raclopride reduced Fos-like immunoreactivity only in the dorso-lateral portion. The results suggest that l-dopa induces c- fos primarily through an activation of D-1 receptors, while D-2 receptor stimulation plays a facilitatory influence on D-1 mediated c- fos expression.