Differential effects of 5-HTTLPR genotypes on inhibition of negative emotional information following acute stress exposure and tryptophan challenge.
Résumé
Previous data suggest that a polymorphism at the serotonin (5-HT) transporter gene (5-HTTLPR) may influence stress resilience and stress-related depression symptoms due to interactions between brain 5-HT dysfunction and stress exposure. Although attentional bias for emotional information has been reliably observed in depression, the interaction between 5-HTTLPR, brain 5-HT vulnerability and acute stress on affective information processing has not yet been investigated. This study examines the effects of tryptophan augmentation (indicating 5-HT manipulation) on inhibition of negative emotional information under stress in mainly female S'/S' versus L'/L' allele carriers. Fifteen female homozygotic short-allele 5-HTTLPR (S'/S'= S/LG, LG/LG) and 13 female homozygotic long-allele 5-HTTLPR (L'/L'= LA/LA) subjects were tested for mood and inhibition of emotional information in a double-blind placebo-controlled design before and after stress exposure following tryptophan manipulation. Stress exposure significantly impaired inhibition of negative affective information only in S'/S' carriers, whereas L'/L' carriers even showed increased inhibition of negative information. The S'/S' allele 5-HTTLPR genotype increases cognitive-attentional bias for negative emotional information under acute stress. Since this bias is an important component of depression, this may be a mediating mechanism making S'/S'-allele carriers more vulnerability for stress-induced depression symptoms. Moreover, current data suggest that L'/L'-allele genotypes are more resilient, even increasing cognitive emotional (inhibitory) control after stress.
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