Objective To compare the difference of brain functional connectivity between diarrhea-predominant irritable bowel syndrome(IBS-D) patients and healthy volunteers and changes after acupuncture intervention

so as to investigate the underlying mechanism of acupuncture in regulating functional activities of IBS-D patients by using seed point correlation analysis. Methods A total of 25 IBS-D patients and 25 healthy volunteers were recruited in the present study and respectively attributed to acupuncture group and control group. The IBS-D patients received manual acupuncture stimulation of Baihui(GV20)

Yintang(EX-HN3)

and bilateral Tianshu(ST25)

Zusanli(ST36)

Shangjuxu(ST37)

Sanyinjiao(SP6) and Taichong(LR3) with mind-regulating and spleen-strengthening technique for 30 min

once a day

3 days a week for 6 weeks. Before and after the intervention

the IBS symptom severity scale(IBS-SSS) was used to assess the patients' state of abdominal pain

distention and defecation

and Hamilton Anxiety Rating Scale(HAMA) employed to evaluate the patients' anxiety severity. The resting state functional magnetic resonance imaging(rs-fMRI) data were acquired and preprocessed by using SPM8 and DPARSE soft-wares. Seeds(bilate-ral hippocampus regions) to whole-brain analysis was performed to obtain the mean time series of the left and right seed regions

followed by making Pearson correlation analysis to obtain the correlation coefficient(time series from each seed region with the rest of the voxels in the brain)

and making a multivariate comparative correction to get data of functional connectivity(FC) of bilateral hippocampus regions and to find the related difference in the brain regions. Then

the differences of the FC of brain regions between IBS-D patients and healthy volunteers were compared. Results Following acupuncture treatment

both the HAMA and IBS-SSS scores were significantly reduced in the acupuncture group compared with its pre-treatment(P<0.01). Compared with the healthy volunteers

there were a reduction in the functional connectivity between the left hippocampus seed region and the right inferior temporal gyrus

left fusiform gyrus and left superior gyrus

and between the right hippocampus region and the right fusiform gyrus

left inferior temporal gyrus

left inferior occipital gyrus

left rectus gyrus

left insula

left precuneus

right angular gyrus

left middle occipital gyrus

right precuneus

and the left superior temporal gyrus

and an increase in the FC between the left hippocampus and left superior temporal gyrus was increased in ISB-D patients. Self-comparison showed that after the treatment

the FC was increased between the left hippocampus seed region and the right inferior temporal gyrus

left fusiform gyrus

bilateral lingual gyrus

left amygdala

right inferior occipital gyrus

right insula

right middle frontal gyrus

left middle frontal gyrus and the left middle occipital gyrus; and between the right hippocampus seed region and the posterior inferior cerebellar lobe

left inferior temporal gyrus

left suboccipital gyrus

right fusiform gyrus

left insula

right inferior frontal gyrus

left superior temporal gyrus

left middle occipital gyrus

right middle frontal gyrus

left supplementary motor area and right supplementary motor area

and decreased between the left hippocampus region and the left anterior cingulate

paracingulate gyrus and the right posterior central gyrus in IBS-D patients. Conclusion Mind-regulating and spleen-strengthening acupuncture intervention may improve the abdominal pain and distension and emotional state in IBS-D patients

which is possibly associated with its effect in enhancing FC between the hippocampus and brain regions.