Objective: To compare the analgesic effects of electroacupuncture(EA) at different stimulating intensities and different treatment intervals so as to explore a suitable set of therapeutic parameters for chronic pain.Methods: A total of 70 Wistar rats were randomized into model(n=10)

1 mA-EA(n=30) and 5 mA-EA(n=30) groups which of the later two groups were further divided into 1 time(t)/day(d)

1 t/3 d and 1 t/week(w) EA subgroups

with 10 cases in each subgroup.Chronic constrictive injury(CCI) pain model was established by loosely ligating the sciatic nerve near the proximal side of the bifid site.Paw withdrawal latency(PWL) was detected once every other day by using radiant heat source to radiate the rat's bilateral hind-paws.The difference values between the affected limb and the healthy limb were used to judge changes of the pain threshold.EA (2/15 Hz

1 mA

5 mA) was respectively applied to bilateral "Zusanli"(ST 36)-"Yanglingquan"(GB 34) for 30 min

once everyday

every 3 days and every week in different subgroups.Results: 1) When 1 mA stimulating current was used

in comparison with model group

the mean difference values of PWL in 1 t/d-EA

1 t/3 d-EA and 1 t/w-EA subgroups from the 1

s

t day to 21st day to 21

s

t day after EA were significantly lower(P

<

0.05);while comparison among the 3 EA subgroups showed that the mean difference values of PWL in 1 t/3 d and 1 t/w subgroups were significantly higher than those of 1 t/d group(P

<

0.05)

indicating that 1 t/d-EA

1 t/3 d-EA and 1 t/w-EA at the lower intensity all had a marked analgesic effect and that of 1 t/d-EA was the best.In addition

the accumulative effect in 1 t/3 d and 1 t/w subgroups was apparent along with the increase of the therapeutic times.2) When 5 mA stimulating current was used

compared with model group

the mean difference values of PWL in 1 t/d-EA subgroup and in 1 t/w-EA subgroup from the 1st day after EA were significantly lower(P

<

0.05);while comparison among the 3 EA subgroups showed that the mean difference values of PWL in 1 t/3 d and 1 t/w subgroups were significantly higher than those of 1 t/d group(P

<

0.05)

indicating that 1 t/d-EA

1 t/3 d-EA and 1 t/w-EA at the lower intensity all had a marked analgesic effect and that of 1 t/d-EA was the best.In addition

the accumulative effect in 1 t/3 d and 1 t/w subgroups was apparent along with the increase of the therapeutic times.2) When 5 mA stimulating current was used

compared with model group

the mean difference values of PWL in 1 t/d-EA subgroup and in 1 t/w-EA subgroup from the 1

s

t day to 21st day to 21

s

t day were significantly lower(P

<

0.05)

displaying that at the higher stimulating current

1 t/d-EA and 1 t/w-EA subgroups had apparent analgesic effects

while 1 t/3 d-EA had no marked analgesic effect.3) When EA treatment was given once everyday

the mean difference values of PWL in 1 mA group decreased significantly faster(P

<

0.05)

meaning that the analgesic effect of lower stimulating intensity EA was significantly better than that of higher stimulating intensity in CCI rats.Conclusion: In the treatment of neurogenic pain with EA

both lower and higher stimulating intensities have an apparent analgesic effect

the effect of lower intensity is remarkably superior to that of higher intensity;when lower intensity EA is applied

the analgesic effect of 1 t/d is the best

and the accumulative effect is definite;when the higher intensity EA applied

the analgesic effect of 1 t/d and 1 t/w is the best.