Objective: To observe the effects of electroacupuncture (EA) on gastrointestinal motility and the ultrastructure of interstitial cells of Cajal (ICC) and the expressions of c-kit receptor protein and stem cell factor (SCF) mRNA in diabetic gastroparesis (DGP) rats, so as to explore its mechanism.
Methods: Fifty SD rats were randomly divided into normal, model, acupoint, non-acupoint and metoclopramide groups (n＝10 rats/group). DGP model was established by intraperitoneal injection of streptozotocin (STZ, 2%), and raised with high-sugar high-fat diet irregularly. EA (sparse-dense, 10 Hz/50 Hz, 2 mA, 20 min) was applied at "Zusanli" (ST 36), "Liangmen" (ST 21) and "Sanyinjiao" (SP 6), and the corresponding non-acupoints of the 3 acupoints, daily for 15 days. The rats in metoclopramide group received intragastric administration of metoclopramide (1.7%, 1 mL/100 g) for 15 days, once a day. Blood sugar was determined with One Touch blood glucose test paper. The gastric emptying rate (GER) and the intestinal propulsion rate (IPR) were measured by intragastric phenol red. The ultrastructure of ICC was detected by transmission electron microscopy. The expression levels of c-kit receptor protein and SCF mRNA of gastric antrum were examined respectively by Western blot and RT-PCR.
Results: Compared with the normal group, the blood glucose significantly increased in the model group (P<0.01), while the GER, IRP and the expression level of SCF mRNA in the gastric antrum significantly decreased (P<0.01), and the ultrastructure of ICC appeared apoptosis-like changes. The blood glucose of the EA group was obviously decreased compared with that of the model group (P<0.05); the GER and IRP significantly increased(P<0.05, P<0.01); the expression level of SCF mRNA increased (P<0.01), the number of ICC increased and its ultrastructure was repaired. There was some relief on ICC ultrastructure in the acupoint group compared with that in the non-acupoint group; and SCF mRNA increased (P<0.05). There was no significant difference on c-kit receptor expression among all the modeling groups (P＞0.05).
Conclusions: EA at ST 36, etc. can regulate the blood glucose and improve gastrointestinal emptying in DGP rats. The mechanism may be related to up-regulating SCF mRNA, repairing ICC ultrastructure, restoring the pacing function, and improving gastrointestinal motility.
Keywords: Diabetic gastroparesis; Electroacupuncture; Gastrointestinal motility; Interstitial cells of Cajal (ICC); SCF-kit.