DIFFERENCES IN D-2 DOPAMINE-RECEPTOR BINDING IN THE NEOSTRIATUM BETWEEN CATS HEMIDECORTICATED NEONATALLY OR IN ADULTHOOD

In order to study differences in response to neocortical injury sustai ned at different ages at the neurotransmitter level, we examined the d ensity in D-2 dopamine receptors in the neostriatum of cats hemidecort icated neonatally (N = 4) or in adulthood (N = 4), as well as in intac t brains (N = 6). Receptor densities were measured using quantitative autoradiography and [H-3]-spiperone binding in 12 regions of the neost riatum and nucleus accumbens septi. We found that the anterior lateral caudate nucleus on both sides of the brain contained a higher D-2 rec eptor density in neonatal-lesioned as compared to adult-lesioned brain s. Ipsilateral to the lesion, the increase was 101% (P < 0.05) and con tralaterally it amounted to 77% (P < 0.05). Moreover, this region of t he ipsilateral caudate nucleus of neonatal-lesioned cats tended to be more densely labeled than that of intact brain by 58% (P < 0.1). D-2 r eceptor densities in adult-lesioned cats did not differ from that of i ntact controls. Comparison of these data with those of a former morpho logical study using the same animals suggested that this bilateral ele vation of D-2 receptor density in neonatally lesioned brains represent s a higher mean density of binding sites per neuron. The elevation in the neonatal-lesioned cats might be a response of the striatum to neur oplastic changes in the striatal neuropil, including the corticostriat al afferents, since such changes are different in neonatal-as compared to adult-lesioned cats. (C) 1998 Elsevier Science B.V.