Pramipexole attenuates the dopaminergic cell loss induced by intraventricular 6-hydroxydopamine

The D-3 preferring dopamine agonist pramipexole has been shown to attenuate the cell loss induced by levodopa in vitro. Pramipexole was herein evaluat ed in the 6-hydroxydopamine lesion model to determine its in vivo effect. R ats were treated with pramipexole or saline before and after an intracerebr oventricular 6-hydroxydopamine injection. In the preliminary study, 6-hydro xydopamine produced a 68% reduction in striatal dopamine and a 62% loss in tyrosine hydroxylase immunoreactive (THir) cell counts in the substantia ni gra. Pramipexole treated animals exhibited a 29% and a 27% reduction in str iatal dopamine and THir cell counts, respectively. THir cell counts and str iatal dopamine were significantly correlated. In the stereological study, 6 -hydroxydopamine reduced THir cell counts by 47% in saline treated animals and 26% in pramipexole treated animals. These data demonstrate that pramipe xole attenuates the biochemical and THir cell changes normally produced by 6-hydroxydopamine consistent with its neuroprotective actions in vitro.