EFFECTS OF GR-68755 ON D-AMPHETAMINE-INDUCED CHANGES IN MOOD, COGNITIVE PERFORMANCE, APPETITE, FOOD PREFERENCE, AND CALORIC AND MACRONUTRIENT INTAKE IN HUMANS

Pre-clinical studies have suggested that 5-HT3 antagonists such as GR 68755 oppose mesocorticolimbic dopamine release, which may mediate the important effects of d-amphetamine on positive subjective mood, anore xia, and performance. Twenty-six healthy male volunteers received each of the following treatments in a double-blind, randomized, cross-over design separated by a period of four to seven days: (a) d-amphetamine (20 mg orally); (b) placebo; (c) GR 68755 (2 mg orally); and (d) GR 6 8755 plus d-amphetamine. Subjects completed subjective measures of moo d, hunger, and satiety. Caloric and macronutrient intake were measured using a test meal. Performance and attention were assessed using stan dardized computerized tasks. GR 68755 enhanced accuracy on the compute rized attention task but failed to reverse significantly any of the ef fects of d-amphetamine. These results suggest that at these doses GR 6 8755 pre-treatment does not significantly reduce the effects of d-amph etamine.