5HT3 receptor antagonists do not block nicotine induced hyperactivity in rats.
The effects of 5-HT3 receptor antagonists (ondansetron 0.1 mg kg-1 SC 30 min; bemesetron 0.03 mg kg-1 SC 45 min) on nicotine-induced increases in locomotor activity were measured in male Sprague-Dawley rats. Intermittent daily injections of nicotine (0.3-1.2 mg kg-1 SC 30 min) resulted in increased locomotor activity as measured by photocell counts. The effect of nicotine was not affected by administration of the 5-HT3 receptor antagonists at doses that are reported to block nicotine- and morphine-induced place-preference conditioning. Neither of the 5-HT3 receptor antagonists tested affected activity counts in vehicle treated animals. Nicotine-induced hyperactivity was blocked by the dopamine antagonist haloperidol (0.03 mg kg-1 SC 2 h) and by the nicotinic antagonist mecamylamine (1 mg kg-1 SC 1 min). The effects of a range of doses (0-1 mg kg-1) of the 5-HT3 receptor antagonists ondansetron, bemesetron, granisetron and tropisetron on hyperactivity induced by 0.6 mg kg-1 nicotine were then assessed. Only tropisetron at 1 mg kg-1 attenuated nicotine-induced hyperactivity. To demonstrate the efficacy of the present range of doses of the 5-HT3 receptor antagonists in this study, conditioned taste aversion experiments were conducted. Ondansetron (0.1 mg kg-1) failed to attenuate a conditioned taste aversion to saccharin induced by nicotine (0.6 mg kg-1), but did induce a reduction in saccharin preference in choice tests following three saccharin-ondansetron pairings.(ABSTRACT TRUNCATED AT 250 WORDS)
Arnold
B
B
Department of Psychiatry, University of Alberta, Edmonton, Canada.
Allison
K
K
Ivanová
S
S
Paetsch
P R
PR
Paslawski
T
T
Greenshaw
A J
AJ
D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D017829:Granisetron / Q000494:pharmacology; D006220:Haloperidol / Q000494:pharmacology; D007211:Indoles / Q000494:pharmacology; D008297:Male; D009043:Motor Activity / Q000187:drug effects*; D009538:Nicotine / Q000494:pharmacology*; D017294:Ondansetron / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D012702:Serotonin Antagonists / Q000494:pharmacology*; D013997:Time Factors; D014326:Tropanes / Q000494:pharmacology; D000077526:Tropisetron
D017829:Granisetron; D006220:Haloperidol; D007211:Indoles; D009538:Nicotine; D017294:Ondansetron; D012702:Serotonin Antagonists; D014326:Tropanes; D000077526:Tropisetron; C042253:bemesetron