Reversal of visceral hypersensitivity in rat by Menthacarin®, a proprietary combination of essential oils from peppermint and caraway, coincides with mycobiome modulation

BackgroundIrritable bowel syndrome (IBS) is a common gastrointestinal disorder associated with altered gastrointestinal microflora and increased nociception to colonic distension. This visceral hypersensitivity can be reversed in our rat maternal separation model by fungicides. Menthacarin((R)) is a proprietary combination of essential oils from Mentha x piperita L. and Carum carvi. Because these oils exhibit antifungal and antibacterial properties, we investigated whether Menthacarin((R)) can reverse existing visceral hypersensitivity in maternally separated rats. MethodsIn non-handled and maternally separated rats, we used the visceromotor responses to colorectal distension as measure for visceral sensitivity. We evaluated this response before and 24hours after water-avoidance stress and after 7days treatment with Menthacarin((R)) or control. The pre- and post-treatment mycobiome and microbiome were characterized by sequencing of fungal internal transcribed spacer 1 (ITS-1) and bacterial 16s rDNA regions. In vitro antifungal and antimicrobial properties of Menthacarin((R)) were studied with radial diffusion assay. Key ResultsMenthacarin((R)) inhibited in vitro growth of yeast and bacteria. Water-avoidance caused visceral hypersensitivity in maternally separated rats, and this was reversed by treatment. Multivariate analyses of ITS-1 and 16S high throughput data showed that maternal separation, induced changes in the myco- and microbiome. Menthacarin((R)) treatment of non-handled and maternally separated rats shifted the mycobiomes to more similar compositions. Conclusions & InferencesThe development of visceral hypersensitivity in maternally separated rats and the Menthacarin((R))-mediated reversal of hypersensitivity is associated with changes in the mycobiome. Therefore, Menthacarin((R)) may be a safe and effective treatment option that should be tested for IBS.