Localization of cholecystokinin and vasoactive intestinal peptide in lower biliary tract in cats following electroacupuncture on right Qimen (LR14) and Riyue (GB 24): an immunohistochemistry study.

Accumulating evidence has shown that control of the motility of the sphincter of Oddi (SO) involves a complex interaction between nerves, neurotransmitters and gastrointestinal hormones such as vasoactive intestinal peptide (VIP) and cholecystokinin (CCK). Our previous studies demonstrated that electroacupuncture (EA) modulated the SO motility in cats and rabbits through activation of nonadrenergic non-cholinergic (NANC) pathway. This study was designed to investigate the changes of neurotransmitters such as CCK and VIP in lower biliary tract in cats receiving EA stimulation. After cats were anesthetized with intramuscular injection of ketamine hydrochloride, they were prepared to conduct EA stimulation on right Qimen (LR14) and Riyue (GB 24). The parameters of EA were 6 pulses/ 3 sec and 45 pulses/ 3 sec alternatively in frequency, 1-2 mA in intensity and 20 min in stimulation duration. After the completeness of EA stimulation, visceral organs such as gallbladder, duodenum and the sphincter of Oddi were removed and frozen for immunohistochemistry localization of CCK and VIP. The results showed that the distribution of CCK-labeled cells in duodenum, gallbladder and SO were more and distinct after EA than before EA stimulation. Whereas, the VIP-labeled cells were significantly more and distinct in duodenum and SO, but not in gall bladder. We conclude that EA regulates the biliary motility though increasing the distribution of CCK- and VIP-containing cells in duodenum and the sphincter of Oddi.