Moxibustion Regulates Gastrointestinal Motility via HCN1 in Functional Dyspepsia Rats

Abstract

BACKGROUND Moxibustion therapy has been found to ameliorate clinical symptoms of functional dyspepsia (FD). We aimed to examine the regulatory effect of moxibustion on the gastrointestinal (GI) motility in FD and explore the underlying mechanism based on the hyperpolarization-activated cyclic nucleotide-gated cation channel 1 (HCN1). MATERIAL AND METHODS Moxibustion therapy was used in FD rats induced by using classic tail-pinch and irregular feeding. Weight gain and food intake were recorded weekly, followed by detecting gastric residual rate (GRR) and small intestine propulsion rate (IPR). Next, western blotting was performed to determine the expression levels of HCN1 in the gastric antrum. qRT-PCR was used to detect HCN1 in the small intestine and hypothalamic satiety center. Double immunolabeling was used for HCN1 and ICCs in gastric antrum and small intestine. RESULTS The obtained results suggested that moxibustion treatment could increase weight gain and food intake in FD rats. The GRR and IPR were compared among the groups, which showed that moxibustion treatment could decrease GRR and increase IPR. Moxibustion increased the expression of HCN1 in the gastric antrum, small intestine, and hypothalamic satiety center. Histologically, the co-expressions of HCN1 and ICCs tended to increase in gastric antrum and small intestine. Meanwhile, HCN channel inhibitor ZD7288 prevented the above-mentioned therapeutic effects of moxibustion. CONCLUSIONS The results of the present study suggest that moxibustion can effectively improve the GI motility of FD rats, which may be related to the upregulation of HCN1 expression in gastric antrum, small intestine, and satiety center.

Figure 1

The weight gain (A) and food intake (B) of rats (n=10/group) (mean±SEM). ^### P<0.001 vs N group; ** P<0.001 vs M group; ^Δ P<0.05, ^ΔΔ P<0.01 and ^ΔΔΔ P<0.001 vs MD; ^&&& P<0.001 vs MB group.

Figure 2

HCN1 expression in the gastric antrum tissues of rats by western blotting (n=4/group). (mean±SEM). ^### P<0.001 vs N group;** P<0.01and *** P<0.001 vs M group; ^ΔΔΔ P<0.001 vs MD group; ^& P<0.05 vs MB group.

Figure 3

Double immunofluorescence staining of c-kit and HCN1 in gastric tissues. Red, c-kit; Green, HCN1; Blue, DAPI.

Figure 4

(A) Quantitative analysis of c-kit and HCN1 fluorescence luminance in gastric antrum of FD rats (n=3/group). (mean±SEM). (B) Quantitative analysis of c-kit and HCN1 fluorescence luminance in small intestine of rats (n=3/group). (mean±SEM). ^### P<0.001 vs N group; *** P<0.001 vs M group; ^ΔΔ P<0.01 vs MD group; ^ΔΔΔ P<0.001 vs MD group.

Figure 5

(A) HCN1 expression in the upper segments of small intestine (RT-PCR) of rats (n=4/group) (mean±SEM). (B) HCN1 expression in the satiety center of the hypothalamus of rats (n=4/group) (mean±SEM). ^### P<0.001 vs N group; *** P<0.001 vs M group; ^ΔΔ P<0.01 vs MD group; ^&&& P<0.001 vs MB group.

Figure 6

Double immunofluorescence staining of c-kit and HCN1 in upper small intestinal tissues. Red, c-kit; Green, HCN1; Blue, DAPI.

Figure 7

GRR (A) and IPR (B) of rats (n=10/group) (mean±SEM). ^### P<0.001 vs N group; *** P<0.001 vs M group; ^ΔΔΔ P<0.001 vs MD group; ^&&& P<0.001 vs MB group.