Gut microbiota and voluntary alcohol consumption.

Alcohol is part of the usual diet of millions of individuals worldwide. However, not all individuals who drink alcohol experience the same effects, nor will everyone develop an alcohol use disorder. Here we propose that the intestinal microbiota (IMB) helps explain the different consumption patterns of alcohol among individuals. 507 humans participated in this study and alcohol consumption and IMB composition were analyzed. On the other hand, in 80 adult male Wistar rats, behavioral tests, alcohol intoxication, fecal transplantation, administration of antibiotics and collection of fecal samples were performed. For identification and relative quantification of bacterial taxa was used the bacterial 16 S ribosomal RNA gene. In humans, we found that heavy episodic drinking is associated with a specific stool type phenotype (type 1, according to Bristol Stool Scale; p < 0.05) and with an increase in the abundance of Actinobacteria (p < 0.05). Next, using rats, we demonstrate that the transfer of IMB from alcohol-intoxicated animals causes an increase in voluntary alcohol consumption in transplant-recipient animals (p < 0.001). The relative quantification data indicate that the genus Porphyromonas could be associated with the effect on voluntary alcohol consumption. We also show that gut microbiota depletion by antibiotics administration causes a reduction in alcohol consumption (p < 0.001) and altered the relative abundance of relevant phyla such as Firmicutes, Bacteroidetes or Cyanobacteria (p < 0.05), among others. Benjamini-Hochberg false discovery rate (FDR) correction was performed for multiple comparisons. These studies reveal some of the consequences of alcohol on the IMB and provide evidence that manipulation of IMB may alter voluntary alcohol consumption.

The influence of dopaminergic polymorphisms on selective stopping.

Although the genetic influence on global stopping has been extensively investigated, little is known about the genetic contribution to other more complex forms of inhibitory control such as selective stopping. The selectivity of inhibitory control can be assessed by using the stimulus-selective stop-signal task. Notably, recent behavioural and neural evidence indicates that individuals can adopt selective but also non-selective stopping strategies to solve it. This study aimed to investigate for the first time the influence of two relevant dopaminergic polymorphisms (in COMT and DRD2 genes) on stimulus-selective stopping in a sample of 529 adults. Results showed that although none of these polymorphisms (neither individually nor in combination) modulate the latency of the stop process in each strategy (the stop-signal reaction time), the choice of strategy was influenced by their interaction. These results suggest that dopaminergic polymorphisms might influence strategy adoption in selective stopping paradigms, which constitutes a novel finding.