title: Behavioral and neurochemical recovery from partial 6-hydroxydopamine lesions of the substantia nigra is blocked by daily treatment with D1/D5, but not D2, dopamine receptor antagonists.
abstract: To determine whether D1/D5 dopamine (DA) receptors play a role in normalization of DA extracellular levels of striatal DA and behavioral recovery after partial 6-OHDA lesions of the substantia nigra, animals were treated on days 1-8 after lesioning with the D1/D5 DA receptor antagonists SCH 23390 (0.1 mg/kg, s.c.) and SCH 39166 (1.0 mg/kg, s.c.), the inactive enantiomer SCH 23388 (0.1 mg/kg, s.c.), the D2 antagonist eticlopride (0.1 mg/kg, i.p.), or saline. Spontaneous turning behavior was assessed on days 3 and 15. Basal extracellular DA and metabolites were measured in both striata using microdialysis on days 16 and 17, 8-9 d after termination of drug treatments. On day 3, all animals turned ipsilateral to the lesion. On day 15, animals previously treated with either saline, eticlopride, or SCH 23388 showed no behavioral asymmetries, whereas animals treated with SCH 23390 or SCH 39166 turned ipsilaterally. On days 16 and 17, extracellular DA did not differ on the two sides in animals treated with saline or eticlopride and were higher on the lesioned side after SCH 23388. In animals treated with the D1/D5 receptor antagonists, however, basal levels of DA were lower on the lesioned side, showing no evidence of normalization. These results suggest a role for the D1/D5 DA receptor in the development of compensatory changes in the DA neurons that accompany behavioral recovery from partial lesions of nigrostriatal DA system.
authors.affiliation: Center for Studies in Behavioral Neurobiology, Department of Psychology, Concordia University, Montreal, Quebec, Canada H3G 1M8.
authors.forename: A
authors.initials: A
authors.lastname: Emmi
authors.forename: H
authors.initials: H
authors.lastname: Rajabi
authors.forename: J
authors.initials: J
authors.lastname: Stewart
mesh_terms: D015102:3,4-Dihydroxyphenylacetic Acid / Q000378:metabolism; D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects; D001552:Benzazepines / Q000494:pharmacology; D004298:Dopamine / Q000378:metabolism; D018492:Dopamine Antagonists / Q000494:pharmacology; D065127:Dopamine D2 Receptor Antagonists; D006719:Homovanillic Acid / Q000378:metabolism; D008297:Male; D017551:Microdialysis; D016627:Oxidopamine; D051381:Rats; D017208:Rats, Wistar; D017447:Receptors, Dopamine D1 / Q000037:antagonists & inhibitors*; D050641:Receptors, Dopamine D5; D013378:Substantia Nigra / Q000737:chemistry / Q000187:drug effects* / Q000378:metabolism; D013565:Sympatholytics
chemical_list: D001552:Benzazepines; D018492:Dopamine Antagonists; D065127:Dopamine D2 Receptor Antagonists; C493607:Drd5 protein, rat; D017447:Receptors, Dopamine D1; D013565:Sympatholytics; C058081:ecopipam; D015102:3,4-Dihydroxyphenylacetic Acid; D050641:Receptors, Dopamine D5; D016627:Oxidopamine; D004298:Dopamine; D006719:Homovanillic Acid