We examined effects of electro-acupuncture on the jaw opening reflex. Using rats anesthetized with pentobarbital sodium (40mg/kg: intraperitoneal) the jaw opening reflex was evoked by electrical stimulation of the dental pulp. The reflex was evoked by electro-myograms were recorded from the digastric muscle, showing di- or triphasic potentials with latency of about 6 msec. The dental pulp stimulation was preceded by single pulse electroacupuncture (EA) of the fore- or hind-leg.
Facilitation followed by inhibition of the jaw opening reflex was induced by the EA. The facilitation lasted for about 20 msec and 30 msec in case of the fore- and hind-leg EAs, respectively. The following inhibition was observed up to about 300 msec and 400 msec after the fore- and hind-le2 EA9, respectively.
It is worthy of note that train pulse EAs diminished inhibition of the jaw opening reflex.