"At the genus level, antidepressants reduced abundances of Ruminococcus, Adlercreutzia, and an unclassified Alphaproteobacteria. To examine implications of the dysregulated bacteria, we chose one of antidepressants (duloxetine) and investigated if its antidepressive effects can be attenuated by simultaneous treatment with Ruminococcus flavefaciens or Adlercreutzia equolifaciens. Supplementation with R. flavefaciens diminished duloxetine-induced decrease in depressive-like behavior, while A. equolifaciens had no such effect. R. flavefaciens treatment induced changes in cortical gene expression, up-regulating genes involved in mitochondrial oxidative phosphorylation, while down-regulating genes involved in neuronal plasticity. Our results demonstrate that various types of antidepressants alter gut microbiota composition, and further implicate a role for R. flavefaciens in alleviating depressive-like behavior. Moreover, R. flavefaciens affects gene networks in the brain, suggesting a mechanism for microbial regulation of antidepressant treatment efficiency."
"Based on a series of experiments, duloxetine and Ruminococcus flavefaciens found that the supplementation of R. flavefaciens reduced or even abolished antidepressive and antianhedonic properties of duloxetine. Most importantly, the authors found reduced levels of serotonin and noradrenaline as a result of R. flavefaciens supplementation."
Note - A prominent source of Ruminococcus flavefaciens probiotic bacteria is fermented barley grass which may be found readily on Amazon. It takes time to buildup in the digestive tract but it may be worth a try.