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

Background: Irritable 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® 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® can reverse existing visceral hypersensitivity in maternally separated rats. Methods: In 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 24 hours after water-avoidance stress and after 7 days treatment with Menthacarin® 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® were studied with radial diffusion assay. Key Results: Menthacarin® 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® treatment of non-handled and maternally separated rats shifted the mycobiomes to more similar compositions. Conclusions & Inferences: The development of visceral hypersensitivity in maternally separated rats and the Menthacarin®-mediated reversal of hypersensitivity is associated with changes in the mycobiome. Therefore, Menthacarin® may be a safe and effective treatment option that should be tested for IBS. © 2018 The Authors. Neurogastroenterology & Motility Published by John Wiley & Sons Ltd. Chemicals / CAS: decanoic acid, 334-48-5, 3398-75-2; fluconazole, 86386-73-4; octanoic acid, 124-07-2, 1984-06-1, 74-81-7; peppermint oil, 8006-90-4; streptomycin, 57-92-1