[Effect of acupuncture for pain threshold among the groups of different constitutions]

To observe the difference in acupuncture for pain threshold at different time points among the groups of 9 TCM constitutions.

The cross-sectional survey was adopted to investigate TCM constitutions among 600 subjects and determine 9 TCM constitution types (neutral constitution, qi-deficiency constitution, yang-deficiency constitution, yin-deficiency constitution, phlegm-damp constitution, damp-heat constitution, blood-stagnation constitution, qi-stagnation constitution, special diathesis constitution). The same acupuncture manipulation was applied to Zusanli (ST 36) on the left side in the subjects and the needle was retained for 30 min. The tenderness threshold was detected with 2390 type Von Frey apparatus at different time points, named before acupuncture, at the moment after qi arrival, in 10 min of needle retaining, in 30 min of needle retaining and in 15 min after needle withdrawal in the subjects of 9 TCM constitutions.

The interactive effect happened between the constitution type and time point (P < 0.05). Among the groups of 9 TCM constitutions, the pain threshold values at the moment after qi arrival (except blood-stagnation constitution, qi-stagnation constitution, special diathesis constitution) in 10 min of needle retaining and in 30 min of needle retaining were increased as compared with those before acupuncture separately (P < 0.01), among which, the value increase was the most significant in 30 min of needle retaining. The differences in the pain thresholds were significant in 15 min after needle withdrawal in the groups of neutral constitution and damp-heat constitution as compared with those before acupuncture (both P < 0.01). In 10 min of needle retaining and in 30 min of needle retaining, as compared with the group of neutral constitution, the changes in pain thresholds of the rest abnormal constitutions were apparently lower (all P < 0.05).

Acupuncture at Zusanli (ST 36) presents different effects among the groups of different constitution types. The effect maintaining durations are different.