Characteristic upregulation of dopamine D1-receptor in rat striatum after 6-hydroxydopamine treatment.
We measured the number of D1-receptors (Bmax) in the striatum whose dopaminergic terminals were destroyed to various degrees by 6-hydroxydopamine (6-OHDA) to clarify the relationship between the degree of denervation and the change in Bmax for D1-receptor. Rats were sacrificed 28 days after 6-OHDA treatment, and [3H]SCH23390 (R(+)-7-chloro-8-hydroxy-3-methyl-1-phenyl-2,3,4, 5-tetrahydro-1H-3-benzazepine) binding capacity and monoamine content were measured in striatal homogenate. Bmax was significantly upregulated when dopamine content was reduced to less than 5% of that in the vehicle-treated striatum. In contrast, it was significantly decreased when dopamine content was 5-25% of that in the vehicle-treated striatum. The D1-receptors showed either upregulation or downregulation depending on the degree of denervation.
Iwata
S
S
Department of Pharmacology, Faculty of Medicine, University of Kagoshima, Japan.
Shimizu
T
T
Nomoto
M
M
Fukuda
T
T
D000818:Animals; D001552:Benzazepines / Q000378:metabolism; D003342:Corpus Striatum / Q000737:chemistry / Q000187:drug effects*; D008297:Male; D016627:Oxidopamine / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D017447:Receptors, Dopamine D1 / Q000032:analysis / Q000187:drug effects*; D017448:Receptors, Dopamine D2 / Q000032:analysis / Q000187:drug effects; D013134:Spiperone / Q000378:metabolism; D015854:Up-Regulation
D001552:Benzazepines; D017447:Receptors, Dopamine D1; D017448:Receptors, Dopamine D2; D013134:Spiperone; D016627:Oxidopamine