Examination of GABAergic and dopaminergic compounds in the acquisition of nicotine-conditioned hyperactivity in rats.
In rats, a distinct environment repeatedly paired with nicotine (0.421 mg/kg base, s.c.) comes to evoke an increase in activity in the absence of any drug. This hyperactivity indicates a Pavlovian-conditioned association between the environment and nicotine. We investigated whether a dopamine D(1) receptor antagonist (SCH-23390), a D(2)/D(3) antagonist (eticlopride) or a GABA(B) agonist (baclofen) would prevent the acquisition of nicotine-conditioned hyperactivity. In saline-pretreated rats, acute nicotine suppressed activity during the conditioning phase (i.e. environment-nicotine pairings); chronic nicotine stimulated activity. Pretreatment with SCH-23390 (0.01 mg/kg, i.p.) attenuated the activating effects of nicotine without affecting controls. Eticlopride (0.03-0.07 mg/kg, i.p.) and baclofen (0.625 and 1.25 mg/kg, i.p.) did not affect nicotine-induced activity in a selective manner. Regardless of the pretreatment drug, rats acquired the environment-nicotine association as indexed in a drug-free test. The inability of SCH-23390 to block the acquisition of nicotine-conditioned locomotor activity is notable because in past research SCH-23390 blocked expression of the learned association.
Palmatier
Matthew I
MI
Department of Psychology, University of Nebraska at Lincoln, NE 68588-0308, USA.
Bevins
Rick A
RA
D000818:Animals; D001418:Baclofen / Q000008:administration & dosage / Q000494:pharmacology*; D001552:Benzazepines / Q000494:pharmacology; D003214:Conditioning, Classical / Q000187:drug effects*; D018492:Dopamine Antagonists / Q000494:pharmacology; D065127:Dopamine D2 Receptor Antagonists; D018755:GABA Agonists / Q000008:administration & dosage / Q000494:pharmacology*; D058788:GABA-B Receptor Antagonists; D008297:Male; D009043:Motor Activity / Q000187:drug effects*; D009125:Muscle Relaxants, Central / Q000494:pharmacology; D009538:Nicotine / Q000008:administration & dosage / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D011954:Receptors, Dopamine / Q000187:drug effects*; D017447:Receptors, Dopamine D1 / Q000037:antagonists & inhibitors; D050637:Receptors, Dopamine D3; D018080:Receptors, GABA-B / Q000187:drug effects*; D012457:Salicylamides / Q000494:pharmacology
D001552:Benzazepines; D018492:Dopamine Antagonists; D065127:Dopamine D2 Receptor Antagonists; C493595:Drd3 protein, rat; D018755:GABA Agonists; D058788:GABA-B Receptor Antagonists; D009125:Muscle Relaxants, Central; D011954:Receptors, Dopamine; D017447:Receptors, Dopamine D1; D050637:Receptors, Dopamine D3; D018080:Receptors, GABA-B; D012457:Salicylamides; D009538:Nicotine; D001418:Baclofen; C045989:eticlopride