[Duality of dopaminergic receptors. Pharmacologic and clinical perspectives]

A univocal disorder of dopaminergic activity in the nerve structures responsible for extra-pyramidal motility does not take into account the total phenomena seen in psychomotor neurological studies. The hypothesis of two categories of dopaminergic receptors-respectively excitatory (DA) and inhibitory (DAi)--in the striatal and mesolimbic structures concerned, was derived from experimental and clinical anatomical cytological, and pharmacological data. This duality of the receptors could establish a relationship between dopaminergic mediating, mechanism and adrenergic mediation for with the existence of a least two types of distinct receptors, alpha and beta, has been demonstrated. The author discusses the physiopathology of neuromotor disorders wuch as Parkinson's disease, chorea, and various types of dyskinesias, in relation to this dual mediation. By separation of dopamine antagonists and agonists in this new context, it should be possible to have a more selective approach, which would be better adapted, therefore, for the treatment of these affections. The study of the effects of a new medication, tiapride, on dyskinesias provoked by levodopa in parkinsonian patients, is a step forwards in this new method exploration in neurology.