Objective To observe the effect of electroacupuncture(EA)stimulation of"Ganshu"(BL18)on expression of substance P(SP)in the gastric mucosa and hypothalamus tissues and hippocampal 5-hydroxytryptamine(5-HT)content in rats with depression+gastric ulcer

so as to explore its mechanism underlying improvement of depressive gastric ulcer.MethodsA total of 60SD rats were equally randomized into normal

model

EA-BL18and non-acupoint groups.The depression+gastric ulcer model was established by chronic unpredictable mild stress(CUMS)paradigm for 21days in accordance with Willner and colleagues' methods(1987)

and injection of 90% glacial acetic acid(0.01mL)into the sub-serous layer near the gastric antrum under anesthesia on day 10after starting CUMS.Following modeling

EA(4Hz/15Hz

2V)was applied to bilateral"Ganshu"(BL 18)for 20min

once daily for 2weeks

with one day's interval between two weeks.The non-acupoint was located about 2.5 cm lateral to the umbilicus and stimulated by EA similar to EA-BL18.The rats' locomotor ability was assessed by open field tests(crossing and rearing numbers).The gastric ulcer index was calculated according to Guth's method

and hypothalamic and gastric antrum SP immunoactivity was determined by immunohistochemistry and hippocampal 5-HT content was detected by ELISA. Results After modeling

compared to the normal group

both crossing number and rearing number of open field tests on day 21 and 34were significantly decreased in the model group(P<0.01)

while compared to the model group

both crossing and rearing numbers on day 34were considerably increased in the EA-BL18group(P<0.01)rather than in the non-acupoint group(P>0.05).Following modeling

the gastric ulcer index

SP expression levels in the gastric antrum and hypothalamus tissue were obviously increased in the model group(P<0.01)

and notably decreased in the EA-BL18group(P<0.01)but not in the nonacupoint group(P>0.05).The hippocampal 5-HT content was remarkably lower in the model group than in the normal group

but obviously higher in the EA-BL18group than in the model group(P<0.01).No significant difference was found between the model and non-acupoint groups in the hippocampal 5-HT content(P>0.05).Conclusion EA of"Ganshu"(BL18)can promote locomotor and reduce gastric ulcer index in depression+gastric ulcer rats

which may be related to its effects in lowering gastric and hypothalamic SP immunoactivity and in raising hippocampal 5-HT content.