Abstract
Effects of local application of capsaicin (CAP) to peripheral nerve on electro-acupuncture (EA) analgesia were examined in rats. Changes in paine thresholds by the EA were examind using tail-flick, hot-plate and Jaw-opening reflex methods. In the tail-flick methods, and hot-plate the latency of responses to heat noxious stimuli were measured in awake rats. In the jaw-opening reflex method, the EMG amplitude of digstric muscle in response to electrical stimulation of the tooth pulp of the incisor was measure in lightly anesthetized rats. Cap was topically treated on the right side of the radial, ulner and medial nerves of the animal's forepaw. The application of the EA to the CAP-untreated left side of the animal's forepaw produced significant changes in the latencies and the EMG amplitude, indicating the abolishment of the EA analgesia by CAP treatment.
These results suggest that CAP-sensitive primaly afferents are responsible for the EA analgesia measured by there different methodes.
