Effects of Rifaximin on Central Responses to Social Stress—a Pilot Experiment
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Probiotics that promote the gut microbiota have been reported to reduce stress responses, and improve memory and mood. Whether and how antibiotics that eliminate or inhibit pathogenic and commensal gut bacteria also affect central nervous system functions in humans is so far unknown. In a double-blinded randomized study, 16 healthy volunteers (27.00 ± 1.60 years; 9 males) received either rifaximin (600 mg/day) (a poorly absorbable antibiotic) or placebo for 7 days. Before and after the drug intervention, brain activities during rest and during a social stressor inducing feelings of exclusion (Cyberball game) were measured using magnetoencephalography. Social exclusion significantly affected (p < 0.001) mood and increased exclusion perception. Magnetoencephalography showed brain regions with higher activations during exclusion as compared to inclusion, in different frequency bands. Seven days of rifaximin increased prefrontal and right cingulate alpha power during resting state. Low beta power showed an interaction of intervention (rifaximin, placebo) × condition (inclusion, exclusion) during the Cyberball game in the bilateral prefrontal and left anterior cingulate cortex. Only in the rifaximin group, a decrease (p = 0.004) in power was seen comparing exclusion to inclusion; the reduced beta-1 power was negatively correlated with a change in the subjective exclusion perception score. Social stress affecting brain functioning in a specific manner is modulated by rifaximin. Contrary to our hypothesis that antibiotics have advert effects on mood, the antibiotic exhibited stress-reducing effects similar to reported effects of probiotics (supported by NeuroGUT, a EU 7th Framework Programme ITN no. 607652; ClinicalTrials.gov identifier number NCT02793193).
KeywordsGut–brain axis Antibiotic Stress Cyberball MEG
The research leading to these results has received funding from the People Programme of the European Union’s Seventh Framework Programme under Research Executive Agency Grant agreement no. 607652 (NeuroGUT).
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PE is responsible for the integrity of the work—the inception of the study and publication of the work. HW contributed to the design of the study, data collection and analysis, drafting of the manuscript, and critical revisions of the manuscript. CB and PE contributed to the design of the study, data analysis, and critical revisions of the manuscript. All authors approved the final version of the manuscript.
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The authors declare that they have no conflicts of interest.
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