This study was performed, using c-fos, to investigate the effect of TENS on pain model induced by capsaicin in spinal level. Twelve rats with 200-250g body weight were randomly divided into three groups: One group which induced by capsaicin, another group which applicated TENS with low frequency(4Hz, 200 us, 20min) and the other group which applicated TENS with high frequency(100Hz, 500s, 20 min).
The results of this study were as follows:
1. The number of c-fos immunoreactive neurons in superficial dorsal horn was increased markedly 2 hours after capsaicin injection, and decreased gradually from 4 hours to 16 hours after injection.
2. At 2hours after capsaicin injection, both low frequency and high frequency TENS decrease the number of c-fos immunoreactive neurons in superficial dorsal horn.
3. In acute pain model, low frequency TENS greatly decrease c-fos expression than high frequency TENS.
Therefore, decreasing the number of c-fos immunoreactive neurons which increased after capsaicin injection with application of TENS indicate that both of the TENS have inhibitory effect. In addition, low frequency TENS greatly decreased the number of neurons explains low frequency TENS is more effective than high frequency TENS in acute pain.
This study also can become a part of scientific evidence on electrotherapy through measuring quantitively effects of TENS in pain mocked.
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