Acupuncture is a commonly used therapy for treating functional diarrhea (FD), although there is limited knowledge on the mechanism. The objectives of this study were to investigate the differences in brain activities elicited by acupuncture between FD patients and healthy controls (HC) so as to explore the possible mechanism. Eighteen FD patients and eighteen HC received 10 sessions of acupuncture treatment at ST25 acupoints. Functional magnetic resonance imaging (fMRI) scans were, respectively, performed before and after acupuncture. The defecation frequency, Bristol stool form scale (SBFS), and MOS 36-item Short Healthy Survey (SF-36) were employed to evaluate the clinical efficacy. After acupuncture, the FD patients showed a significant decrease in defecation frequency and BSFS score. The regional homogeneity (ReHo) map showed a decrease in the paracentral lobule and postcentral gyrus, and an increase in the angular gyrus, insula, anterior cingulate cortex (ACC), and precuneus in the FD group. Moreover, the changes in ReHo values in the ACC were correlated with the reduction in defecation frequency. Decreasing functional connectivity among the ACC, insula, thalamus, and orbital frontal cortex only existed in the FD group. Conclusively, acupuncture alleviated defecation frequency and improved stool formation in FD patients. The efficacy might result from the regulation of the homeostasis afferent processing network.
Functional diarrhea (FD), one of the functional gastrointestinal disorders (FGID), is characterized by chronic diarrhea in the absence of structural or biochemical abnormalities that explain the symptoms [
Acupuncture, an important traditional Chinese medicine (TCM) therapy, has been used to treat gastrointestinal symptoms for centuries in China. Now it has been increasingly accepted as a complementary and alternative treatment for functional gastrointestinal disorders in western countries [
Altered perceptual responses and reflex within the brain-gut axis have been proposed as a generally accepted model to explain the cardinal symptoms of FGID [
We hypothesize that if acupuncture therapy is effective, it would improve gut function and couple with regulation of disease-related brain regions. In this study, we sought to investigate the differences in brain activity between FD patients and healthy controls (HC) after acupuncture using functional mapping with fMRI. We first identified regions showing different brain regional homogeneity (ReHo) after acupuncture in FD patients compared with controls. Then, we tested whether some of these regions were correlated with symptom changes. Finally, we explored functional connectivity alterations after acupuncture in both FD and HC.
Eighteen FD patients were recruited from September 2011 to December 2012. The inclusion criteria were as follows. (1) Patients were right-handed and aged between 20 and 30 years; (2) they matched the Rome III diagnosis criteria for FD [
Eighteen age and sex-matched right-handed HC were recruited by advertisement. Each healthy volunteer was free from any gastrointestinal symptoms or sign and accepted a review of medical history and a physical examination to exclude disease carriers and medication users. All healthy volunteers signed the informed consent.
Both FD patients and HC accepted 10 sessions total of acupuncture treatment over a period of 2 weeks (5 sessions per week). The acupuncture treatment was performed on ST25 (Tianshu), which are classical acupuncture points for diarrhea. The acupuncture points were punctured bilaterally (Figure
(a) Location of acupoints, (b) experimental paradigm.
The outcome in this study included the following items: the times of defecation and the score of the Bristol Stool Form Scale (BSFS) throughout the second week, the physical component summary (PCS) score and the mental component summary (MCS) score of the MOS 36-item Short Health Survey (SF-36) [
The experiment was carried out on a 3-T Siemens magnetic resonance scanner (Allegra; Siemens Medical System, Germany) at the MR Research Center of the West China Hospital at Sichuan University, Chengdu, China. The heads of the subjects were secured carefully with a comfortable holder, and ear plugs were used to reduce scanner noise. Prior to the functional run, a high-resolution structural image for each subject was acquired by the volumetric three-dimensional spoiled gradient recalled sequence (TR = 1900 ms; TE = 2.26 ms; data matrix, 256 × 256 mm2). Two expert radiologists examined the structural images of the participants to exclude the possibility of clinically silent lesions. The resting-state functional images were obtained with echo planar imaging (30 continuous slices with a thickness of 5 mm each; TR = 2000 ms; TE = 30 ms; flip angle, 90°; field of view, 240 × 240 mm2; data matix, 64 × 64; total volumes, 180).
The clinical data were analyzed by the SPSS 16.0 statistical software (SPSS Inc., Chicago, IL, USA). All the numerical variables in this paper are presented as mean ± standard deviation (SD). Two independent-sample
Regional homogeneity (ReHo), a data-driven method, analyzes the blood oxygen level-dependent signals of the brain, which could help reveal the high complexity of the human brain function [
ReHo changes in FD patients or HC were determined by the contrast between baseline and after treatment. Statistical parametric maps were constructed by computing a paired
Functional connectivity has been used to describe the relationship between the neuronal activation patterns of anatomically separated brain regions, which reflect the level of functional communication between regions [
There was an insignificant difference in the age and gender between the two groups, which were comparable (Table
Baseline characteristics.
Characteristic | Healthy controls |
Functional diarrhea |
|
---|---|---|---|
Age (y) |
|
|
0.144 |
Male/female | 10/8 | 10/8 | |
Defecation times |
|
|
0.000 |
BSFS score |
|
|
0.000 |
PCS score |
|
|
0.000 |
MCS score |
|
|
0.006 |
BSFS: Bristol stool form scale; PCS: physical component summary; MCS: mental component summary.
Presented values are mean ± SD.
In the HC group, the change in defecation frequency, BSFS score, PCS score, and MCS score were not significant (
Clinical outcome measurements pre- and postacupuncture stimulation.
Characteristic | Healthy controls |
|
Functional diarrhea |
|
||
---|---|---|---|---|---|---|
Pre |
Post |
Pre |
Post |
|||
Defecation times |
|
|
0.144 |
|
|
0.000 |
BSFS score |
|
|
0.858 |
|
|
0.001 |
PCS score |
|
|
0.808 |
|
|
0.085 |
MCS score |
|
|
0.751 |
|
|
0.711 |
BSFS: Bristol stool form scale; PCS: physical component summary; MCS: mental component summary.
Presented values are mean ± SD.
In the FD group, a decrease in ReHo was observed in the middle temporal gyrus, paracentral lobule, postcentral gyrus, and thalamus, while an increase in ReHo was observed in the middle frontal gyrus, angular gyrus, insula, ACC, and precuneus (
Regional homogeneity (ReHo) changes in functional diarrhea (FD) patients and healthy controls (HC) after acupuncture (
The correlation coefficients of Regional homogeneity (ReHo) and clinical variables. (a) In the functional diarrhea (FD) group, compared with preacupuncture, the defecation frequency postacupuncture was significantly decreased (
In the FD group, the supplementary motor area, inferior frontal gyrus, orbital frontal cortex (OFC), thalamus, and insula were found to be negatively correlated with the left ACC after acupuncture (
Functional connectivity network of ACC-L changes in functional diarrhea (FD) patients and healthy controls (HC) after treatment (
In the present study, we investigated the cumulative effects of acupuncture stimulation on the resting-state brain activity of FD and compared them with HC. Clinical outcome showed that acupuncture was effective for the FD but had no effect on the HC. Neuroimaging results demonstrated the similarities and differences between FD and HC.
In this study, an increased ReHo in the middle frontal gyrus and a decreased ReHo in the thalamus and temporal cortex were found in both groups after acupuncture treatment. The middle frontal gyrus belongs to the dorsolateral prefrontal cortex (DLPFC), which is generally considered as a cognitive brain region. The DLPFC is directly interconnected with the sensorimotor cortex and indirectly connected with limbic structures that process internal information. The DLPFC is critical for arbitrary associations between sensory cues, rewards, and voluntary actions [
In this study, acupuncture stimulation elicited more extensive cerebral ReHo changes in the FD group as compared with the HC group. The increases in the angular gyrus, precuneus, ACC, and insula and the decrease in the paracentral lobule and postcentral gyrus were found only in the FD group but not in the HC group. Furthermore, the correlation analysis showed a negative relationship between the variation of ReHo in the ACC and the change in defecation frequency after acupuncture in the FD group. The ACC, insula, and somatosensory cortex were the main components of the visceral sensory neuromatrix, which is commonly described by the term “homeostatic afferent processing network” [
As ReHo of the left ACC increased after acupuncture and showed a negative correlation with the change in defecation frequency, we chose this region as the region of interest (ROI) to investigate the resting-state functional connectivity change after acupuncture stimulation. Both groups showed significantly decreased functional connectivity in the left ACC to the PFC and motor cortex compared with preacupuncture. Besides, decreased functional connectivity in the left ACC was also found in insula, thalamus and OFC in the FD group. The extent of structural links between the ACC and the lateral PFC and motor cortices is one of the most striking cortico-cortical connectivities in the primate frontal cortex [
As mentioned above, ReHo map showed some brain regions involved in the homeostatic afferent processing network and DMN in the FD group changes but not in the HC group after acupuncture. Among these brain regions, change in the ACC is related to clinical symptom alleviation. Moreover, the ACC-related functional connectivity network indicated that the homeostatic afferent processing network only changed in the FD group. This meant acupuncture could regulate the unbalanced organism state, and the homeostasis afferent processing network might play a key role in the central mechanism of treating FD by stimulation at ST25.
Some limitations should be taken into account when interpreting the results of this study. First, the sample size was small (18 subjects for each group). Better results would have been gained with a larger sample. Second, the participants received acupuncture for ten sessions during two weeks. Intestinal symptoms of the FD group were alleviated after treatment, but quality of life did not improve significantly due to such short treatment time. Longer treatment cycle is recommended in future studies.
This study revealed the similarities and differences in resting-state ReHo and the functional connectivity response between the FD patients and HC with the same acupuncture stimulation. Modulation of the sensory, cognition, and motor pathways might be the common mechanism of acupuncture treatment in different groups. Some brain regions only changed in the FD group. More importantly, these changes were negatively correlated with the change in the defecation frequency. Our results demonstrated that acupuncture influenced the left ACC and the homeostatic afferent processing network during the resting state. Our findings hope to shed light on the underlying mechanisms of acupuncture on ST25 for FD.
Anterior cingulate cortex
Dorsolateral prefrontal cortex
Default mode network
Functional diarrhea
Functional magnetic resonance imaging
Family-wise error
Functional gastrointestinal disorders
Full width at half-maximum
Healthy controls
Regional homogeneity
Region of interest
Kendall’s coefficient of concordance
Mental component summary
Orbital frontal cortex
Physical component summary
Positron emission tomography
Self-rating Anxiety Scale
Bristol Stool Form Scale
MOS 36-item Short Health Survey
Self-rating Depression Scale
Statistical Parametric Mapping 5
Traditional Chinese medicine.
The authors declare they have no conflict of interests.
This work was supported by grants from the National Key Basic Research Program of China (973 Program, no. 2011CB505205), the Youth Foundation of Sichuan Province (no. 2012JQ053), and the Youth Foundation of National Natural Science Foundation of China (no. 81001504, no. 81101108).