Impact of Ethanol and Saccharin on Fecal Microbiome in Pregnant and Non-Pregnant Mice

Research identifying connections between the gastrointestinal flora and human health has developed at a rapid pace. Several studies link the gut microbiome to a variety of biological functions beyond the gastrointestinal tract. Changes in our diets, including the consumption of artificial sweeteners, have profound effects on the composition of the gut microbiome and can, in turn, affect brain function, glucose tolerance, and inflammation. Sweeteners are often used to encourage consumption of agents such as ethanol and nicotine in laboratory studies using rodents. Studies aiming to examine the effects of agents like ethanol on the developing nervous system administer these agents during pregnancy. To date, there have been no studies exploring the impact of the combination of dietary ethanol and saccharin during pregnancy on the gut microbiome in either humans or laboratory animal models. In the study presented, we evaluated the impact of ethanol in either water or saccharin on the fecal microbiome in pregnant and non-pregnant mice using a qPCR approach. We found that the combination of ethanol and saccharin produced different effects than ethanol in water, depending on pregnancy status. Levels of Clostridium were reduced in ethanol-saccharin but not ethanol-water drinking mice, even though the total levels of ethanol consumed were the same for the two groups. Eubacteria were increased in the pregnant, but decreased in the non-pregnant, ethanol-saccharin drinking group. These treatment and pregnancy specific changes could impact the development of the offspring. In developing and quality checking our primer sets for these studies we identified several problems within previous research in the field. The technical drawbacks in previous studies, as well as our own study, are discussed. Despite some progress in the ability to study the gut microbiome, more advances and standardization of practices should be established to improve the reliability and validity of microbiome research.