Objective: To compare the effects of electroacupuncture (EA) and moxibustion (Moxi) on visceral pain and expression of vanilloid receptor subtype 1 (VR 1) and heat shock protein (HSP)70 in "Tianshu" (ST 25) region in colorectal distension (CRD)-induced visceral hypersensitivity (VHS) rats.
Methods: Fifty male SD rats were randomly divided into normal control, VHS model, 43℃-moxi, 46℃-moxi, 1 mA-EA and 3 mA-EA groups (n=10 in each group). The VSH model was established by CRD once daily for 14 days. EA or Moxi stimulation was applied to bilateral "Tianshu" (ST 25) for 10 min, once daily for consecutive 10 days. The abdominal withdrawal reflex (AWR) scores (0-4 points) were rated according to Al-Chaer's and coworkers' standards (2000) and the expression levels of VR 1 and HSP 70 in bilateral ST 25 area tissues detected by immunohistochemistry.
Results: The AWR scores for 20, 40, 60 and 80 mmHg CRD pressures were significantly increased compared to the normal control group (P<0.01) and notably decreased after 43℃- and 46℃-moxi, and 1 mA- and 3 mA-EA stimulation of bila-teral ST 25 in comparison with the model group (P<0.05, P<0.01), and the effect of 46℃-moxi was apparently superior to those of 1 mA-EA at 40 and 80 mmHg, and 3 mA-EA at 40 mmHg (P<0.05). After modeling, the expression of both VR 1 and HSP 70 (percentages of area of positive-cells) in ST 25 region had no significant changes (P>0.05). Compared to the model group, the expression levels of VR 1 in the 43℃-moxi and 46℃-moxi groups, and HSP 70 in the 43℃-moxi and 46℃-moxi, 1 mA-EA and 3 mA-EA groups were significantly up-regulated (P<0.01), but without obvious changes in the expression of VR 1 in the 1 mA-EA and 3 mA-EA groups (P>0.05). The effects of 46℃-moxi were considerably better than those of 43℃-moxi, 1 mA-EA and 3 mA-EA in up-regulating VR 1 and HSP 70 expression (P<0.05, P<0.01). No significant differences were found among the 43℃-moxi, 1 mA-EA and 3 mA-EA groups in the expression of VR 1 and HSP 70 (P>0.05).
Conclusions: Moxibustion at 43℃ and 46℃ and EA at 1 mA and 3 mA, especially the 46℃-moxi, can relieve visceral pain in visceral hypersensitivity rats, which may be related to their effects in up-regulating expression of VR 1 and HSP 70 in "Tianshu" (ST 25) area.