Journal of Neuroscience, Vol 9, 3699-3708, Copyright © 1989 by Society for Neuroscience
Nondopaminergic prefrontocortical efferent fibers modulate D1 receptor denervation supersensitivity in specific regions of the rat striatum
D Herve, F Trovero, G Blanc, AM Thierry, J Glowinski and JP Tassin
Laboratoire de Neuropharmacologie, INSERM U.114, College de France, Paris.
A unilateral injection of 6-OHDA (6 microgram/1.5 microliter) was made into
the fields of Forel in order to estimate the effects of the destruction of
ascending dopaminergic (DA) pathways on the denervation supersensitivity of
DA D1 receptors in the rat striatum. DA-sensitive adenylate cyclase
activity was markedly enhanced in the anteromedian part of the striatum 3
weeks after the lesion (+68%) and remained elevated for several weeks
thereafter (+36%). A different response occurred in the laterodorsal
striatum, where the increase in DA- sensitive adenylate cyclase activity
was less pronounced after 3 weeks (+40%) and no longer present after 7
weeks. Estimations of catecholamine levels indicated that the lesion made
destroyed not only nigrostriatal DA neurons but other ascending
catecholaminergic fibers projecting into the cerebral cortex as well. In
addition, retrograde transport experiments made with wheat germ agglutinin
coupled to horseradish peroxidase indicated that the anteromedian part of
the striatum, but not the laterodorsal one, receives both an ipsi- and
contralateral cortical projection originating in the prefrontocortical DA
field. When the destruction by 6-OHDA of this contralateral DA innervation
was combined to the unilateral lesion of the fields of Forel, the increase
in DA-sensitive adenylate cyclase activity in each striatal area 3 or 7
weeks postlesion was prevented. This effect was due to DA denervation of
the prefrontal cortex since striatal D1 denervation supersensitivity was
still observed when contralateral ascending noradrenergic fibers were
selectively destroyed by a 6-OHDA lesion made laterally to the pedunculus
cerebellaris superior. These results suggest that, by controlling the
activity of corticostriatal neurons, the mesocorticoprefrontal DA neurons
exert a permissive role on the development of D1-receptor denervation
supersensitivity in specific areas of the striatum.