Selective cortical infarction reduces [3H]sulpiride binding in rat caudate-putamen: autoradiographic evidence for presynaptic D2 receptors on corticostriate terminals.
Although the existence of presynaptic D2 dopamine receptors on corticostriate terminals has been supported by numerous receptor-binding studies, recent autoradiographic data has failed to demonstrate loss of striatal D2 receptors following cortical lesions. In the present study, Long-Evans rats were subjected to unilateral middle cerebral artery (MCA) infarction in order to produce reproducible lesions of the neocortex without damaging subcortical structures. Animals were sacrificed 2 and 4 wk following lesion and brains were prepared for receptor autoradiography. D2 receptors were studied using the selective ligand [3H]sulpiride, while D1 dopamine receptors were examined using [3H]SCH 23390. Sodium-dependent, high-affinity choline uptake sites were labeled with [3H]hemicholinium-3, thereby providing a quantitative measure of cholinergic neuronal integrity. Unilateral cortical infarction resulted in approximately a 20% reduction in [3H]sulpiride binding in several discrete regions of the ipsilateral caudate-putamen (CPu), but not in the nucleus accumbens. D2 receptor binding was also reduced significantly in some areas of the contralateral CPu when compared with [3H]sulpiride binding in sham-operated, control animals. In contrast, D1 receptors (as identified by [3H]SCH 23390 and high-affinity choline uptake sites (labeled with [3H]-HC-3) were not affected by the cortical lesion. The results provide autoradiographic confirmation of the existence of presynaptic D2 receptors on corticostriate terminals.
Filloux
F
F
Department of Psychiatry, University of Utah School of Medicine, Salt Lake City 84132.
Liu
T H
TH
Hsu
C Y
CY
Hunt
M A
MA
Wamsley
J K
JK
D000818:Animals; D001345:Autoradiography; D003342:Corpus Striatum / Q000378:metabolism*; D007091:Image Processing, Computer-Assisted; D002546:Ischemic Attack, Transient / Q000378:metabolism*; D009411:Nerve Endings / Q000378:metabolism*; D051381:Rats; D011954:Receptors, Dopamine / Q000187:drug effects / Q000378:metabolism*; D017448:Receptors, Dopamine D2; D013469:Sulpiride / Q000378:metabolism*
D011954:Receptors, Dopamine; D017448:Receptors, Dopamine D2; D013469:Sulpiride