Potentiation of the effects of raclopride on sucrose consumption by the 5-HT2 antagonist ritanserin.
We examined the effects on sucrose consumption of a dopamine (DA) D2/D3 antagonist (raclopride, 0-0.3 mg/kg), a serotonin 5-HT2/2c antagonist (ritanserin, 0-0.4 mg/kg), and raclopride (0.15 mg/kg) combined with ritanserin (0-0.4 mg/kg). Three different concentrations of sucrose solution (0.7%, 7.0% and 34%) were tested. The concentration-intake function in drug-free rats was an inverted-U, with 7.0% sucrose supporting the highest intake. Raclopride (0.3 mg/kg) inhibited intake of 7.0% sucrose, but its effect on 0.7% sucrose fell short of significance (P < 0.06) and intake of 34% sucrose was unchanged. Ritanserin did not affect sucrose intake when given on its own, but synergized with a previously ineffective dose of raclopride (0.15 mg/kg) so as to cause a significant inhibition of 7.0% sucrose intake and increase in 34% sucrose intake. These data indicate that 5-HT2 antagonism potentiated the behavioural effects of raclopride and we speculate that this interaction might contribute to the efficacy of atypical neuroleptic drugs.
Montgomery
A M
AM
Psychology Department, London Guildhall University, UK.
Suri
A
A
D000818:Animals; D018492:Dopamine Antagonists / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004326:Drinking / Q000187:drug effects*; D004338:Drug Combinations; D008297:Male; D020891:Raclopride; D051381:Rats; D016713:Ritanserin / Q000494:pharmacology*; D012457:Salicylamides / Q000494:pharmacology*; D013395:Sucrose / Q000494:pharmacology*
D018492:Dopamine Antagonists; D004338:Drug Combinations; D012457:Salicylamides; D016713:Ritanserin; D020891:Raclopride; D013395:Sucrose