Neuropharmacological data on the striatum

: The striatum constitutes the most voluminous basal ganglia in man. It is issued from ganglionic eminences which are very early bound by limbic kernels. If the cortical and reticulo-spinal projections have been first described the existence of anatomical connexions with the limbic system offers a large number of functional possibilities. The knowledge of the distribution of the different chemical substances which are present within this structure as well as the enzymes necessary for their synthesis and destruction permits to establish a chemical mapping, the dopaminergic one being the best known. The dopaminergic synaptic function in the striatum helps to understand the respective roles of the pre and post-synaptic receptors as well as the mechanisms by which the other neuromediators can modulate the dopaminergic activity, the cyclic nucleotides being often necessary for this action. These fundamental data subtend the mechanism of action of most of the drugs which are involved in extrapyramidal phenomenons (neuroleptics, dopaminergic agonists) and allows to put forth physiopathological hypothesis on Parkinson disease, Huntington chorea, as well as certain induced or spontaneous dyskinetic states. The functions of the striatum are then evoked: if the role of this structure in motor control is critical, its involvement in complex behaviours is strongly suggested.