NICOTINIC ACETYLCHOLINE SUBUNIT MESSENGER-RNA EXPRESSION IN DOPAMINERGIC-NEURONS OF THE RAT SUBSTANTIA-NIGRA AND VENTRAL TEGMENTAL AREA

THE molecular composition of the nicotinic acetylcholine receptors (nA ChRs) 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-hy droxydopamine lesion of the dopaminergic system. In contrast to the un lesioned hemisphere, no signal was found in the lesioned hemisphere fo r alpha 3, alpha 5, alpha 6 and beta 4 subunits in the SN nor for alph a 2, alpha 3, alpha 5, alpha 6, alpha 7 and beta 4 subunits in the VTA , indicating the expression of these subunits in dopaminergic neurons. mRNA for alpha 4, beta 2 and beta 3 subunits (and alpha 7 in the SN) were still detected after lesion, suggesting that they are expressed i n GABAergic neurons and interneurons of these brain areas. These resul ts demonstrate the selective localisation of a number of nAChR subunit mRNA within dopaminergic neurons, strongly suggesting that a heteroge nous population of nAChRs play a role in modulating dopaminergic neuro nal activity. NeuroReport 9: 3097-3101 (C) 1998 Lippincott Williams & Wilkins.