title: Neonatal 6-hydroxydopamine lesioning enhances quinpirole-induced vertical jumping in rats that were quinpirole primed during postnatal ontogeny.
abstract: Quinpirole-induced vertical jumping is a phenomenon first observed in rats treated from birth, once a day for 21 days or more, with the dopamine D₂ receptor agonist quinpirole. This quinpirole-induced behavioral sensitization is known as a priming process. To determine whether dopaminergic innervation influenced this priming phenomenon, groups of rats were lesioned at 3 days after birth with the neurotoxin 6-hydroxydopamine (6-OHDA; 67 μg in each lateral ventricle; desipramine pretreatment, 20 mg/kg ip, 1 h). Rats were additionally treated daily from birth with quinpirole HCl (3.0 mg/kg ip, salt form). Controls received saline vehicle in place of 6-OHDA and/or quinpirole. When rats were placed in individual observation cages (1 h acclimation) starting at 20 days after birth, acute quinpirole treatment produced vertical jumping in the quinpirole-primed group; and the effect persisted through the twenty-ninth day. In rats additionally lesioned with 6-OHDA, vertical jumping was enhanced at 20, 24, 26/27, and 28/29 day--with there being as much as a 32-fold increase in vertical jumping versus the group that was primed with quinpirole, but not lesioned with 6-OHDA. This finding indicates that an ontogenetic 6-OHDA lesion enhances quinpirole-induced vertical jumping in rats and that dopaminergic innervation may normally exert a suppressive effect on vertical jumping.
authors.affiliation: Department of Pharmacology, Quillen College of Medicine, East Tennessee State University, P.O. Box 70577, Johnson City, TN 37614, USA. kostrzew@etsu.edu
authors.forename: Richard M
authors.initials: RM
authors.lastname: Kostrzewa
authors.forename: Florence P
authors.initials: FP
authors.lastname: Kostrzewa
mesh_terms: D000818:Animals; D001921:Brain / Q000187:drug effects / Q000254:growth & development; D018491:Dopamine Agonists / Q000494:pharmacology*; D005260:Female; D008297:Male; D009043:Motor Activity / Q000187:drug effects*; D016627:Oxidopamine / Q000008:administration & dosage / Q000633:toxicity*; D011247:Pregnancy; D019257:Quinpirole / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D017448:Receptors, Dopamine D2 / Q000819:agonists
chemical_list: D018491:Dopamine Agonists; D017448:Receptors, Dopamine D2; D019257:Quinpirole; D016627:Oxidopamine