Dopamine transporter mRNA expression is intense in rat midbrain neurons and modest outside midbrain

Dopamine transporter mRNA expression in individual neurons from the substantia nigra pars compacta, 'All' area, arcuate nucleus of the hypothalamus, retina, and olfactory bulb was assessed by in situ hybridization. High levels of expression were noted over individual neurons in midbrain nuclei; much lower expression was found in cells of the inner nuclear layer of the retina, glomerular cell layer of the olfactory bulb, and medial aspect of the arcuate nucleus of the hypothalamus. The low levels of expression in the latter nuclei are consistent with the paucity of effects of cocaine in visual and olfactory systems, failure to detect photoaffinity-labelled transporter protein in hypothalamus or olfactory bulb, and observations that little or no damage is found in dopaminergic neurons outside the basal midbrain in idiopathic Parkinsonism.