Ether-à-go-go 1 (Eag1) potassium channel expression in dopaminergic neurons of basal ganglia is modulated by 6-hydroxydopamine lesion

Abstract

The ether à go-go (Eag) gene encodes the voltage-gated potassium (K(+)) ion channel Kv10.1, whose function still remains unknown. As dopamine may directly affect K(+) channels, we evaluated whether a nigrostriatal dopaminergic lesion induced by the neurotoxin 6-hydroxydopamine (6-OHDA) would alter Eag1-K(+) channel expression in the rat basal ganglia and related brain regions. Male Wistar rats received a microinjection of either saline or 6-OHDA (unilaterally) into the medial forebrain bundle. The extent of the dopaminergic lesion induced by 6-OHDA was evaluated by apomorphine-induced rotational behavior and by tyrosine hydroxylase (TH) immunoreactivity. The 6-OHDA microinjection caused a partial or complete lesion of dopaminergic cells, as well as a reduction of Eag1+ cells in a manner proportional to the extent of the lesion. In addition, we observed a decrease in TH immunoreactivity in the ipsilateral striatum. In conclusion, the expression of the Eag1-K(+)-channel throughout the nigrostriatal pathway in the rat brain, its co-localization with dopaminergic cells and its reduction mirroring the extent of the lesion highlight a physiological circuitry where the functional role of this channel can be investigated. The Eag1-K(+) channel expression in dopaminergic cells suggests that these channels are part of the diversified group of ion channels that generate and maintain the electrophysiological activity pattern of dopaminergic midbrain neurons.