Menthacarin induces calcium ion influx in sensory neurons, macrophages and colonic organoids of mice

Menthacarin is a herbal combination that is clinically used for the treatment of functional gastrointestinal disorders (FGIDs). In several clinical studies, Menthacarin reduced visceral hypersensitivity-related symptoms. Pathogenesis of visceral hypersensitivity is multifactorial. This involves several cell types and different transient receptor potential ion channels (TRPs); these ion channels are highly conductive for calcium ions. Since transient changes in cytosolic calcium levels are crucial for many functions of living cells, we investigated if Menthacarin can induce calcium influx in sensory, largely nociceptive, neurons from dorsal root ganglia (DRG), peritoneal macrophages (PMs) and colonic organoids. We employed the calcium imaging technique on sensory neurons from DRG, PMs and colonic organoids isolated from mice. All cells were superfused by Menthacarin at several concentrations (600, 1200, 1800 μg/ml) during the experiments, followed by calcium ionophor ionomycin (Iono., 1 μM) as a positive control. Menthacarin induced concentration-dependent calcium ion influx in all investigated cell types. Furthermore, repeated applications of Menthacarin induced tachyphylaxis (desensitisation) of calcium responses in sensory neurons and colonic organoids. Menthacarin-induced calcium influx into sensory neurons, macrophages and colonic organoids is probably related to its clinical desensitising effects in patients with FGIDs.