Enhanced Pilocarpine-Induced Oral Activity Responses in Neonatal 6-OHDA Treated Rats
Document Type
Article
Publication Date
1-1-1993
Description
Neonatal destruction of rat nigrostriatal dopaminergic fibers results in an enhanced oral activity response to both dopamine (DA) D1 and serotonin (5-HT) agonists. Because cholinergic systems represent another one of the neural circuits involved in oral behavior, it was of interest to determine whether muscarinic receptors might also be sensitized in the lesioned rats. At 3 days after birth, rats were pretreated with desipramine HCl (20 mg/kg, IP) 1 h before 6-hydroxydopamine (6-OHDA) HBr (100 μg in each lateral ventricle) or saline-ascorbic acid (0.1%) vehicle. Between 2 and 4 months, behavioral supersensitivity to a D1 agonist (SKandF 38393) and 5-HT agonist (m-chlorophenylpiperazine; m-CPP) was established before rats were challenged with the muscarinic receptor agonist, pilocarpine HCl (0.125 to 10.0 mg/kg, IP). The pilocarpine dose-effect curve was shifted to the left, with a maximal effect of 63.7 ± 8.6 oral movements being produced by a 1.0 mg/kg pilocarpine HCl dose in the 6-OHDA lesioned rats, versus 15.0 ± 2.4 oral movements in the control group (p < 0.001). The enhanced response to pilocarpine was attenuated by the muscarinic receptor antagonist, scopolamine HCl (0.1 mg/kg IP). These findings indicate that neonatal 6-OHDA treatment produces supersensitization of muscarinic receptors in rats.
Citation Information
Kostrzewa, Richard M.; and Neely, David. 1993. Enhanced Pilocarpine-Induced Oral Activity Responses in Neonatal 6-OHDA Treated Rats. Pharmacology, Biochemistry and Behavior. Vol.45(3). 737-740. https://doi.org/10.1016/0091-3057(93)90534-Z PMID: 8332633 ISSN: 0091-3057