Neonatal 6-Hydroxydopamine Lesioning Enhances Quinpirole-Induced Vertical Jumping in Rats that were Quinpirole Primed During Postnatal Ontogeny

• Published in: Neurotoxicity research 2012-02, Vol.21 (2), p.231-235
• Main Authors: Kostrzewa, Richard M., Kostrzewa, Florence P.
• Format: Article
• Language: English
• Subjects: Animals; Biomedical and Life Sciences; Biomedicine; Brain - drug effects; Brain - growth & development; Cell Biology; Dopamine Agonists - pharmacology; Female; Indexing in process; Male; Motor Activity - drug effects; Neurobiology; Neurochemistry; Neurology; Neurosciences; Oxidopamine - administration & dosage; Oxidopamine - toxicity; Pharmacology/Toxicology; Pregnancy; Quinpirole - pharmacology; Rats; Rats, Sprague-Dawley; Receptors, Dopamine D2 - agonists
• ISSN: 1029-8428; 1476-3524
• DOI: 10.1007/s12640-011-9268-5

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 D 2 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.