Compromised decision-making and increased gambling proneness following dietary serotonin depletion in rats

► Problematic gambling behaviour is associated with poor decision-making in humans. ► l-tryptophan deficient diet was used in rats to reduce 5-HT synthesis during 45 days. ► 5-HT depleted rats did not improve their choice for a best long-term payoff in rIGT. ► Low 5-HT elicits risk-proneness (sub-optimal attraction towards binge reward) in rPDT. ► Relation between individual rIGT versus rPDT performance was disrupted by 5-HT depletion.