Objective

2

To observe the effect of moxibustion on small intestinal mucosal immune barrier in rats with diarrhea-predominant irritable bowel syndrome (IBS-D) and explore its underlying mechanisms.

Methods

2

Of 38 newborn rats from 4 healthy SPF pregnant rats

12 neonatal rats were randomly selected in a normal group. IBS-D model was prepared by the combined measures for the rest rats

including neonatal maternal separation

acetic acid enema and chronic restraint stress. Twenty-four successfully-modeled rats were randomized into a model group and a moxibustion group

12 rats in each one. In the moxibustion group

suspending moxibustion was delivered at bilateral "Tianshu" (ST25) and "Shangjuxu" (ST37)

20 min each time

once daily and for 7 consecutive days. Separately

before acetic acid enema (aged 35 days)

after modeling (aged 45 days) and after intervention (aged 53 days)

the body mass

loose stool rate (LSR) and and the minimum volume threshold when abdominal withdrawal reflex (AWR) scored 3 were observed in the rats of each group. After intervention (aged 53 days)

using HE and PAS staining

the morphology of duodenum was observed

the length of villus and the depth of crypt were measured

the ratio of the length of villus to the depth of crypt was calculated; and the numbers of mucosal intraepithelial lymphocytes (IELs) and goblet cells were counted. With ELISA adopted

the contents of γ-interferon (IFN-γ)

interleukin-4 (IL-4) and secretory immunoglobulin A (sIgA) in duodenal mucosa of rats were detected. The proportion of T cell subsets in duodenal mucosa was detected using flow cytometry. The microvilli and tight junctions of duodenal mucosal epithelial cells were observed by transmission electron microscopy

and the integrity of duodenal mucosa observed by scanning electron microscopy.

Results

2

Compared with the normal group

for the rats in the model group

the body mass

the minimum volume threshold when AWR scored 3

the length of duodenal villus and the the ratio of the length of villus to the depth of crypt

as well as the proportion of CD

8

+

T subset were all reduced (

P

<

0.01

P

<

0.05)

the counts of goblet cells in duodenal mucosa decreased (

P

<

0.01); LRS

the proportion of CD

4

+

T subset and CD

4

+

/CD

8

+

as well as the contents of IFN-γ

IL-4 and sIgA in duodenal mucosa and IFN-γ/IL-4 were all elevated (

P

<

0.01); and the numbers of IELs rose (

P

<

0.01). The morphology of duodenal mucosa was irregular

the villi got shorter

sparse and scattered

with uneven density. The morphology of epithelial cells was destroyed and the tight junctions damaged

with larger spaces. When compared with the model group

in the moxibustion group

the body mass

the minimum volume threshold when AWR scored 3

the length of duodenal villus and the ratio of the length of villus to the depth of crypt

as well as the counts of goblet cells in duodenal mucosa increased (

P

<

0.01); LRS

the proportion of CD

4

+

T subset

and CD

4

+

/CD

8

+

as well as the contents of IFN-γ

IL-4 and sIgA in duodenal mucosa and IFN-γ/IL-4 were reduced (

P

<

0.01); and the numbers of IELs was dropped (

P

<

0.01). The morphology of duodenal mucosa was more regular

the villi were grew

got longer and arranged regularly

with even density. The morphology of epithelial cells was slightly destroyed

and the tight junctions partially damaged.

Conclusion

2

Moxibustion at "Tianshu" (ST25) and "Shangjuxu" (ST37) can reduce visceral hypersensitivity in IBS-D rats and relieve abdominal pain

diarrhea and other symptoms. Its effect mechanism may be related to the repair of small intestinal mucosal immune barrier and the improvement in the immune function in IBS-D.