BACKGROUND: The incidence of gallstone is higher in patients with diabetes mellitus than in general population because of hypomotility and lowered emptying function. The aim of this study was to investigate the gene expression of cholecystokinin-A (CCK-A) receptor in patients with gallstones and diabetes mellitus and its correlation with the hypomotility of the gallbladder.
METHODS: Smooth muscle was taken from the gallbladder after cholecystectomy and total RNA was extracted from it by Trizol reagent to compose cDNA. CCK-A receptor was enlarged by reverse transcription-polymerase chain reaction (RT-PCR) and identified by electrophoresis. Based on the analysis of images, the relative expression of the CCK-A receptor was obtained after comparison of the CCK-A receptor and β-action. The emptying function of the gallbladder was measured with B ultrasound before operation.
RESULTS: Gallbladder ejetion fraction (GBEF2)(%) (24.9±12.7) decreased more significantly in patients with gallstones and diabetes mellitus than in those with simple gallstone (61.5±8.5)(P<0.01). In the two groups, a fraction of 540bp of CCK-A receptor could be testified respectively, but the relative expression was different. Compared to the expression of β-action, it was 0.400±0.068 in patients with gallstones and diabetes mellitus, but 0.622±0.070 in those with gallstone only (F=7.169,  P<0.01). The result was consistent with the decreased contractility.
CONCLUSIONS: The gene expression of CCK-A receptor on the smooth muscle of the gallbladder may decrease more significantly in patients with gallstone and diabetes mellitus than in those with gallstone only; this result is consistent with the decreased motility. Thus the lowered expression of CCK-A receptor is probably the cause of hypomotility in patients with gallstones and diabetes mellitus.