Modulation of Corydalis tuber on glycine-induced ion current in acutely dissociated rat periaqueductal gray neurons.

Traditionally, Corydalis tuber has been used for the control of pain including headache, stomach ache, and neuralgia. In the present study, modulation of the Corydalis tuber on glycine-activated ion current in the acutely dissociated periaqueductal gray (PAG) neurons was studied by a nystatin-perforated patch-clamp technique. High concentrations of Corydalis tuber elicited ion current, which was suppressed by strychnine application, while low concentrations of Corydalis tuber reduced glycine-induced ion current in the PAG neurons. Inhibitory action of Corydalis tuber on glycine-activated ion current was partially abolished by treatment with naltrexone, a non-selective opioid antagonist. Application of N-methylmalemide (NEM), a sulfhydryl alkylating agent, also partially abolished the inhibitory action of Corydalis tuber on glycine-activated ion current in the PAG neurons. These results suggest that the inhibitory effect of Corydalis tuber on glycine-activated ion current in the PAG neurons is one of the analgesic mechanisms of the Corydalis tuber.