DOPAMINE TRANSPORTER MESSENGER-RNA IN PARKINSONS-DISEASE AND CONTROL SUBSTANTIA-NIGRA NEURONS

Dopamine transporter messenger RNA (mRNA) expression was assessed by i n situ hybridization over individual pigmented neurons from the substa ntia nigra pars compacta in midbrain sections from 7 parkinsonian and 7 age-matched, neurologically normal patients. In the normal control b rains, high levels of expression of dopamine transporter mRNA were not ed over pigmented neurons in the substantia nigra pars compacta; neuro ns in the adjacent nucleus paranigralis of the ventral tegmental area displayed less hybridization. Nigra compacta neurons surviving in brai ns of patients with Parkinson's disease displayed only 57% of the dopa mine transporter mRNA hybridization intensity displayed by nigral neur ons in normal control brains. The disease-related decrease in the appa rent level of dopamine transporter mRNA expression in remaining neuron s could reflect neuronal dysfunction. Conceivably, it might also refle ct differential vulnerability of those neurons that initially expresse d higher levels of this transporter to the insult of parkinsonism.