Suppressive Effects of Kambaku-taiso-to on the Yawning Induced by Cholinergic Agonists / 日本東洋医学雑誌

ABSTRACT

The present experiments were performed to investigate effects of a Kampo (Japanese herbal) medicine, Kambaku-taiso-to (Gan-mai-da-zao-tang), on incidence of yawning in rats. Physostigmine, a cholinesterase inhibitor, 0.05-0.1mg/kg s. c., induced yawning responses with a marked effect at 0.05mg/kg. Pilocarpine, a muscarinic receptor agonist, 1-2mg/kg s. c., also induced yawning responses, the maximum effect being observed at a dose of 2mg/kg. Talipexole, a dopaminergic D-2 receptor agonist, 0.02mg/kg s. c., also induced yawning. Kambaku-taiso-to, 250-1, 000mg/kg, was orally administered 30min before injection of physostigmine, pilocarpine or talipexole. The yawning induced by both cholinergic and dopaminergic agents was reduced in a dose-dependent manner by Kambaku-taiso-to. All the yawning responses to cholinergic and dopaminergic agents were also reduced by rauwolscine 0.5mg/kg, yohimbine 2.5mg/kg, α-2 adrenoceptor antagonists, and by scopolamine 0.5mg/kg—muscarinic receptor antagonist. The present findings thus suggest that Kambaku-taiso-to exerts a suppressive effect on the incidence of yawning, and dopaminergic and cholinergic suppression and the indirect suppressive mechanism mediated by the central adrenergic nerve are associated with this suppression.