Inhibitory Effect of Shoseiryuto on Substance P and CGRP Production in the Trigeminal Nerve

Abstract

It has been reported that the effect of shoseiryuto, a traditional Japanese “Kampo” medicine, on allergic rhinitis depends on several mechanisms. Previously, we reported that shoseiryuto administered in an allergic rhinitis rat model, inhibited increases of substance P (SP) and calcitonin gene-related peptide (CGRP) in the nasal mucus, which in turn are involved in the exacerbation of rhinitis symptoms and allergic symptoms. In the present research, we looked into whether the secretion of SP and CGRP are directly inhibited by the administration of shoseiryuto.
Histamine solution 5µl (10 mg/ml) was instilled in both nostrils of healthy, male SD rats, thereby inducing allergic symptoms, and for the group to which shoseiryuto had been pre-administered, increase in the concentration of SP and CGRP in the nasal mucus was significantly inhibited. Moreover, upon investigating SP and CGRP production in the trigeminal ganglia by means of immunostaining, it was found to be similarly significantly inhibited. The above results indicate that shoseiryuto directly inhibits the secretion of SP and CGRP in the C-fibers of nasal mucosa.