The Effect of Nichin-to on the Plasma Gut-Regulatory Peptide Level in Healthy Human Subjects

Nichin-to, a traditional Chinese herbal (Kampo) medicine, has been used to treat nausea and vomiting. Most of traditional herbal medicines are prepared from several different herbs. For example, Nichin-to is a combination of five herbs : Pinelliae Tuber, Zingiberis Rhizoma, Poria, Glycyrrhizae Radix and Aurantii Nobilis Pericarpium. Thus, to determine the exact pharmacological mechanisms of Chinese herbal medicines is very difficult. However, the pharmacological effects of some Chinese herbal medicines can be elucidated from the changes in plasma levels of neuropeptides. In this study, we investigated the effects of Nichin-to on the plasma levels of gut-regulated peptides [gastrin, somatostatin, motilin, vasoactive intestinal peptide (VIP), calcitonin gene-related peptide (CGRP) and substance P] in healthy human subjects. A single oral administration of Nichin-to caused significant (p<0.05) increases in plasma levels of gastrin-, somatostatin-, VIP-, motilin-, CGRP- and substance P-immunoreactive substance (IS), compared with placebo group. In conclusion, these results might indicate that the pharmacological action of Nichin-to is closely related to changes in these peptide levels in human plasma, and we hypothesize that the pharmacological effect of Nichin-to might be due to improvement of digestion, and accelerating the rate of gastric emptying and intestinal propulsion.