Characterisation of the effects of nicotine in the five-choice serial reaction time task in rats: antagonist studies

Citation
A. Blondel et al., Characterisation of the effects of nicotine in the five-choice serial reaction time task in rats: antagonist studies, PSYCHOPHAR, 149(3), 2000, pp. 293-305
Citations number
56
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Neurosciences & Behavoir
Journal title
Volume
149
Issue
3
Year of publication
2000
Pages
293 - 305
Database
ISI
SICI code
Abstract
Rationale: Nicotine has been shown to decrease reaction time and increase a nticipatory responses in a five-choice serial reaction time task (5-CSRTT) in rats, but the receptor mechanisms mediating this effect remain unknown. Objectives: To evaluate further the effects of nicotine in this task and to characterise the receptors mediating these effects. Methods: Using a stand ard 5-CSRTT protocol, rats were trained to respond to a 0.5-s visual stimul us, which was reduced to 0.25 s for experimental sessions to induce a perfo rmance decrement. The effects of acute (0.03-0.3 mg/kg IF) and repeated (0. 1 and 0.3 mg/kg IP for 5 days) nicotine were studied, as was the ability of mecamylamine (1 mg/kg IF), hexamethonium (5 mg/kg IF), dihydro-beta-erythr oidine (6 mg/kg IF) and methyllycaconitine (10 mg/kg IF) to antagonise the effects of acute nicotine. Results: Nicotine had no effect on accuracy, but decreased response latencies, improved performance in the less-well attend ed stimulus locations and increased inappropriate responding after both acu te and repeated treatment. The data suggest that nicotine improves readines s to respond and improves target scanning, and decreases the ability to wit hhold premature responses (i.e. increased impulsivity). Except for the redu ction in error latency, all of the effects of nicotine were antagonised by the non-selective, centrally acting antagonist mecamylamine, whereas the pe ripheral antagonist hexamethonium had no effect, demonstrating that nicotin e's actions are central in origin. Dihydro-beta-erythroidine, a competitive nicotinic antagonist, antagonised all of the effects of nicotine. In contr ast, the a, antagonist methyllycaconitine had no significant effects agains t nicotine. Conclusions: These results demonstrate that the alpha(7) recept or subtype is not involved in the effects of nicotine in the 5-CSRTT and th at its effects are more likely to be mediated by a receptor(s) such as alph a(4)beta(2), alpha(4)beta(4) and/or alpha(3)beta(2) which is sensitive to a ntagonism by dihydro-beta-erythroidine.