title: Compromised decision-making and increased gambling proneness following dietary serotonin depletion in rats.
abstract: Psycho-genetic studies have revealed a role for the brain serotonin system in gambling proneness and poor decision-making. We assessed whether manipulation of brain serotonin levels in rats affected performance in operant-based tasks for decision-making and gambling proneness. Male Wistar rats were exposed to an l-tryptophan (TRP) deficient diet (0.0 g/kg; T- group) or to a control, l-tryptophan containing diet (2.8 g/kg; T+ group). The same rats were tested for decision-making performance in the rodent Iowa Gambling Task (rIGT) using home-cage operant panels, and subsequently for gambling proneness in a Probabilistic Delivery Task (rPDT) using classic Skinnerboxes. At sacrifice, monoamines and metabolites were evaluated with HPLC analysis, confirming a drastically reduced serotonin synthesis, as well as altered dopamine turnover in the prefrontal cortex of T- rats. As expected, control rats (T+) progressively chose the option with the best long-term payoff in the rIGT, and also shifted from "Large & Luck-Linked" (LLL) to "Small & Sure" (SS) reinforcers in the rPDT. In contrast, depleted animals (T-) exhibited a weaker improvement of performance in the rIGT and maintained a sub-optimal attraction for LLL reinforcer in the rPDT. Comparing individual performances in both tests, we found a significant correlation between the two tasks in control (T+) but not in depleted (T-) rats. The present study revealed that (1) brain 5-HT depletion leads to poor decision-making and to gambling proneness; (2) the relationship between these two traits, shown in the control group, was disrupted in 5-HT depleted rats. The data are discussed in terms of changes within forebrain loops involved in cognitive and motivational/affective processes.
authors: Section of Behavioural Neuroscience, Department of Cell Biology and Neurosciences, Istituto Superiore di Sanità, Roma, Italy.
authors: S
authors: S
authors: Koot
authors: F
authors: F
authors: Zoratto
authors: T
authors: T
authors: Cassano
authors: R
authors: R
authors: Colangeli
authors: G
authors: G
authors: Laviola
authors: R
authors: R
authors: van den Bos
authors: W
authors: W
authors: Adriani
mesh_terms: D000818:Animals; D003657:Decision Making / Q000502:physiology*; D004032:Diet; D004298:Dopamine / Q000378:metabolism; D005715:Gambling / Q000378:metabolism* / Q000503:physiopathology; D008297:Male; D009042:Motivation; D017397:Prefrontal Cortex / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D012701:Serotonin / Q000378:metabolism*; D014364:Tryptophan / Q000172:deficiency*
chemical_list: D012701:Serotonin; D014364:Tryptophan; D004298:Dopamine