Abstract:Objective To explore the expression and significance of apoptosis related protein caspase-3 in interstitial cell of Cajal (ICC) in small intestine of rats with functional dyspepsia (FD). Methods Eighty adult Wistar rats of specific pathogen free（SPF）grade (half male and half female) were randomly divided into control group (n=30) and FD model group (n=50). Rats in control group were perfused with normal saline, and rats in FD model group were perfused with Chinese medicine to establish FD rat model. The general state and weight changes of rats were observed during feeding and modeling. After modeling, urinary D-xylose excretion rate and intestinal propulsive rate were determined in each group, and the rats were killed by cervical dislocation. The small intestine was taken from 8 cm distal to the pylorus to measure the number and distribution of ICC by immunofluorescence and to observe the morphological changes of ICC by transmission electron microscope (TEM). Western blot and reverse transcription polymerase chain reaction (RT-PCR) were used to detect the expressions of Caspase-3 protein and mRNA in ICC. Results Compared with those in control group, the average body weight and the urinary D-xylose excretion rate significantly reduced, and ICC presented with smaller volume, fewer organelles, swelling and even vacuolization of cytoplasm, as well as varying degrees of disorder and destruction of the connecting structure with surrounding smooth muscle cells and nerve fiber terminals in FD model group(P<0.05). Confocal fluorescence microscopy showed that the distribution of ICC in the small intestine of FD rats was significantly lower than that in control group (P<0.05). Caspase-3 protein and mRNA expression levels in ICC significantly increased in group B (P<0.05). Conclusion Morphological and structural changes of ICC in rats play a role in the pathogenesis of FD. Apoptosis of ICC in small intestine induced by high expression of Caspase-3 is a possible cause for functional dyspepsia.