Objective: To observe the effect of acupuncture stimulation of Stomach Meridian of Foot-Yangming (ST) acupoints on motilin and gastrin release and the resultant changes of interdigestive migrating motor complex (MMC) of the gastrointestinal tract for clarifying the material basis between ST and gastrointestinal functions.

Methods: MMC was recorded by strain gauge transducers implanted in the gastric antrum, the proximal end of the duodenum and the proximal end of the jejunum separately in 7 dogs. Systolic frequency, average amplitude and dynamic index in 3 normal MMC cycles in the control group were recorded. Blood samples were taken from the external jugular vein once every 10 min in phase I, II, III and IV of MMC for detecting plasma motilin, gastrin and CCK levels. In the ST group, after recording the first MMC cycle and in phase 1 of MMC of the gastric antrum, electroacupuncture (EA) stimulation of "Zusanli" (ST 36), "Tianshu" (ST 25) and "Lianquan" (ST 21) of the Stomach Meridian was given to the dogs. Similarly, in Bladder (BL) Meridian group, effects of EA of Pishu (BL 20), Yinmen (BL 37) and Chengshan (BL 57) were analyzed; and in Gallbladder (GB) Meridian group, effects of EA of Yanglingquan (GB 34), Wushu (GB 27) and Jingmen (GB 25) were observed and analyzed. EA parameters were: frequency being 20 - l00Hz, strength being l2 - l6mA and duration of stimulation being 100min (about one MMC cycle). Plasma motilin and gastrin contents were detected once every l0 min by RIA.

Results: (l) After EA ST Meridian acupoints, the time course was changed considerably, including significant shortening of phase I (quiescent period) and obvious increase of phase II (intermittent systolic period) and phase III (intense systolic period) (P<0.01). It indicated that EA ST Meridian acupoints could strikingly increase the amplitude of MMC phase III of gastric antrum, duodenum and jejunum by 119.5±l7.3%, 110.4±9.3% and 104.7 ±l0.2% respectively (P<0.01). Motility indexes also significantly increased. After EA BL Meridian acupoints, phase III duration shortened, the systolic amplitude and motility indexes decreased. After EA GB Meridian acupoints, the gastrointestinal contraction in phase III was also strengthened but was a little weaker than the effect of EA stimulation of ST Meridian acupoints; (2) In comparison with control group, plasma motilin and gastrin contents of EA ST Meridian group increased apparently by 60.4±7.3% and 171 .2±11 .9% (P<0.01 ) separately. In EA BL Meridian group, plasma motilin and gastrin contents had no any clear changes; (3) After EA, CCK release in GB Meridian group increased significantly (P<0.01), being (l41.0± l3.5% higher than control group, while that of ST Meridian group increased lightly, being only 15.1 ±2.4%) higher than control group. EA BL Meridian acupoints had no any effect on CCK release; (4) The effect of EA ST Meridian plasma motilin and gastrin was partially blocked by intravenous infusion of motilin antiserum (1:100 1ml/hr, 100min) or gastrin receptor antagonist proglumide (25ug/kg · Hr, 100rnin). Intravenous infusion of CCK-A receptor antagonist loxiglumide (200ughg · hr 100min) could block the effect of EA GL Meridian acupoints on gastrointestinal contraction and CCK release.

Conclusion: EA stimulation of acupoints of ST Meridian can enhance functional activity of the gastrointestine, showing a relatively specific effect of the ST Meridian on gastrointestinal movement involving motilin and gastrin release.

By Zhou Lu, Wang Lijian, Yun Dayou & Wang Ling