Objective: To observe the effect of electroacupuncture (EA) of "Zhongwan" (CV12) and "Zusanli" (ST36) in different combinations of stimulating parameters on intragastric pressure (IGP) in normal rats so as to explore their best combinations for promoting gastrointestinal mobility.
Methods: A total of 90 male SD rats were randomly divided into 6 EA groups：CV12-1 mA＋ST36-1 mA, CV12-1 mA＋ST36-2 mA, CV12-1 mA＋ST36-4 mA, ST36-1 mA＋CV12-1 mA, ST36-2 mA＋CV12-1 mA, and ST36-4 mA＋CV12-1 mA which the first acupoint was stimulated first, followed by the second in each group (n＝15 rats/group). Before (1 min), and 0-30 s, 30-60 s, 60 -90 s, and 90-120 s during EA stimulation of the left ST36 or CV12 first or later, the IGP was measured via an inserted intragastric balloon, a connected pressure transducer and an amplifier. Changes of the IGP were analyzed using 2×3×4 factorial design.
Results: 1) During 0-30 s, EA-CV12 showed an obvious inhibitory effect on IGP(P<0.05) while EA-ST36 showed a mild exciting effect (P>0.05). 2) Compared with the IGP level of 0-30 s, the IGP levels of 30-120 s were significantly decreased in all the groups (P<0.01). 3) In the CV12-1 mA/ST 36-1 mA groups, only the IGP level of 0-30 s was affected by the EA-stimulating order (P<0.05). In the CV12-1 mA/ST36-2 mA groups, both the IGP levels during 0-30 s and 90-120 s were obviously affected by EA-stimulating sequence. In the CV12-1 mA/ST36-4 mA groups, the IGP level during 0-120 s was affected by EA-stimulating order. 4) Only in the condition of EA-CV12 stimulating first and EA-ST36 second and at 4 mA, the reduction effect of IGP of EA-CV12 was antagonized. There are marked interaction effects between the EA strength and acupoint EA stimulating sequence, and between the time course and acupoint EA stimulating sequence (P<0.01), but no significant interaction effects were found between the time course and stimulating strength, and among the EA stimulating strength, time course and acupoint EA stimulating sequence (P>0.05).
Conclusion: Simultaneous EA stimulation of ST36 and CV12 has an antagonistic effect on IGP in normal rats, which is affected by the stimulating sequence, stimulating strength and time course.
Keywords: Acupoint stimulating sequence; EA stimulating strength; Electroacupuncture; Intragastric pressure; Time course; Zhongwan (CV12); Zusanli (ST36).