Nicotinic acetylcholine subunit mRNA expression in dopaminergic neurons of the rat substantia nigra and ventral tegmental area

Abstract

THE molecular composition of the nicotinic acetylcholine receptors (nAChRs) located on dopaminergic neurons and modulating their activity is unclear. Using the reverse transcriptase-polymerase chain reaction we have analyzed the mRNA for nAChR subunits expressed in the substantia nigra (SN) and ventral tegmental area (VTA) following unilateral 6-hydroxy-dopamine lesion of the dopaminergic system. In contrast to the unlesioned hemisphere, no signal was found in the lesioned hemisphere for α3, α5, alpha;6, and β4 subunits in the SN nor for α2, α3, α5, α6, α7 and β4 subunits in the VTA, indicating the expression of these subunits in dopaminergic neurons. mRNA for α4, β2 and β3 subunits (and α7 in the SN) were still detected after lesion, suggesting that they are expressed in GABAergic neurons and interneurons of these brain areas. These results demonstrate the selective localisation of a number of nAChR subunit mRNA within dopaminergic neurons, strongly suggesting that a heterogenous population of nAChRs play a role in modulating dopaminergic neuronal activity.