Objective

2

To explore the effect of electroacupuncture (EA) at front-

mu

and back-

shu

points of large intestine on autophagy of Cajal interstitial cells (ICCs) in the colon of rats with slow transit constipation (STC)

and to analyze the mechanism of EA for mitigating STC.

Methods

2

Thirty-six SD rats were randomly divided into a blank group

a model group

an EA group

a mosapride group

an EA+rapamycin (RAPA) group and an EA+3-methyladenine (3-MA) group

with 6 rats in each group. The STC model was established by intragastric administration with loperamide hydrochloride. In the EA group

the EA+RAPA group and the EA+3-MA group

EA was operated at bilateral "Tianshu" (ST25) and "Dachangshu" (BL25)

with dense-disperse waves (2 Hz/15 Hz in frequency)

for 15 min each time. In the mosapride group

intragastric administration with mosapride solution was operated. In the EA+RAPA group and the EA+3-MA group

30 min before acupuncture

the intraperitoneal injection was administered with RAPA and 3-MA solution

respectively. The intervention was delivered once daily and for consecutive 14 days in each group. After model establishment

the defecation time of the first red fecal particle was recorded in each group. After modeling and intervention

the number of fecal particles and fecal quality were recorded in each group over a 24-hour period. After intervention

the small intestinal propulsion rate was calculated in each group. HE staining was used to observe the histological morphology of colonic tissue

transmission electron microscopy was used to observe the ultrastructure of ICCs in the colon tissues

the immunofluorescence assay was used to observe the positive expression of the ICCs marker tyrosine kinase receptor (C-kit) in colonic tissue

the real-time quantitative PCR assay was used to detect C-kit mRNA expression

and Western-blot was used to detect C-kit and autophagy-related protein expression in each group.

Results

2

After modeling

compared with the blank group

the model group exhibited the prolonged defecation time of the first red fecal particle and the reduced number of fecal particles

and the decline of fecal quality and small intestinal propulsion rate (

P

<

0.01). After intervention

compared with the model group

the EA group and the mosapride group showed the increase in the number of fecal particles

fecal quality

and small intestinal propulsion rate (

P

<

0.01). Compared with the EA group

fecal quality and small intestinal propulsion rate were reduced in the EA+RAPA group (

P

<

0.01). Compared with the blank group

the model group showed the impaired colonic mucosal structure and reduced goblet cell count; and autophagosomes and mitochondrial swelling were markedly observed in the cytoplasm of ICCs. The average fluorescence intensity of C-kit

the mRNA expression of C-kit

and the protein expression of C-kit and P62 all decreased

while the protein expression of LC3 and ATG5 increased in the model group (

P

<

0.01). Compared with the model group

all other groups showed the improvements in colonic mucosal structure and ICCs ultrastructure

with the increase in average C-kit fluorescence intensity (

P

<

0.01); the mRNA expression of C-kit and the protein expression of C-kit and P62 were elevated (

P

<

0.01)

while the protein expression LC3 and ATG5 were reduced in the EA group (

P

<

0.01). When compared with the EA group

the prote

in expression of P62 decreased in the EA+3-MA group (

P

<

0.01).

Conclusion

2

Electroacupuncture at front-

mu

and back-

shu

point of large intestine can effectively alleviate intestinal motility disorder in rats with slow transit constipation

which may be related to inhibiting excessive autophagy of ICCs and repairing the structure and quantity of ICCs.