| Sphincter of Oddi dysfunction (SOD), whose symptom is clinical abdominal pain or recurrent pancreatitis, is a syndrome caused by the obstruction at sphincter of oddi level. It is one of the main causes of post-cholecystectomy syndrome (PCS) and more frequently recognized in postcholecystectomy patients. However, there isn't ideal therapy yet due to its unclear mechanism. The present studies are to interpret it from the regulatory change of SO, but it is far from satisfactory . Therefore, to set up an animal model of cholecystectomy and to explore the change of SO after cholecystectomy is of great importance. The sphincter of Oddi (SO) is a complex, valve-like, neuromuscular structure located at the junction of the bile and pancreatic ducts with the duodenum and is under the double regulation of nerve and hormone and contacts with bile-cyst through regionally nervous reflex. Luman and colleagues reported that cholecystectomy at least temporarily suppresses the normal inhibitory effect of pharmacological doses of CCK on the SO. Wang et al found that the intracellular calcium (Ca2+) concentration was increased in cultured SO cell incubated with cholesterol liposome. Calcium channel antagonists such as nifedipine has also been reported decrease the basal tone and contractile activity of the SO and to relieve the painful symptoms in patients with SO dyskinesia. The change of Ca2+ concentration in SO cell not only affects contraction of muscle cell directly, but also regulates the corresponding downstream signal transduction. The pathway of CaN-Nuclear Factor of Activated TCells is broadly distributed in many tissue such as myocardium, skeletal muscle, detrusor muscle and vascular smooth muscle. It plays an essential role in T cell activation and attributes to the hypertrophy of myocardium, skeletal muscle and detrusor muscle. Studies on pathological cardiac hypertrophy showed that when intracytoplasm calcium concentration increased, calcineurin (the only serine/threonine protein phosphatase under the control of Ca2+/calmodulin) was activated. Activated calcineurin directly dephosphorylates cytosolic NFAT, resulting in their nuclear translocation and activation of hypertrophy response genes.Myosin heavy chain (MHC) varied from majorityα-MHC to majorityβ-MHC and the synthesis of cardiac transforming growth factor-β(TGF-β) increased. The aim of this study is to set up an animal model of cholecystectomy, examining the pressure of SO, investigating the expressions of the functional SO proteins and the different expressions between CnAαand CnAβ(the main two catalytic subunits of Calcineurin), and exploring the regulatory role of Calcineurin (CaN) in the early-stage change of sphincter of Oddi after cholecystectomy.ObjectiveBased on an animal model of cholecystectomy to examine the pressure of SO by manometry; investigate the changes of functional proteins and structure change of SO; detect the different expressions between the main two catalytic subunits of Calcineurin: CnAαand CnAβ, exploring its role in the change of sphincter of Oddi at the early-stage after cholecystectomy.Methods68 New Zealand rabbits were divided into four groups: group A, B, C and D. In group A, rabbits were only subjected to laparotomy and brood for 4 weeks, while in group B,C and D, rabbits were subjected to cholecystectomy and brood for 2, 4 and 8 weeks respectively. When time is up, 8 rabbits in both group A and C were sacrificed after Sphincter of Oddi Manometry and the sphincter of Oddi were taken for HE stain. The other rabbits were sacrificed directly and the tissues of sphincter of Oddi were subjected to experiment. 2 rabbits in both group A and group D were examined by transmission electro microscope. MHC protein expression was examined by Western blot.The mRNA and protein expression of CnAαand CnAβwas examined respectively by RT-PCR and Western blot.Results1. The basic pressure and wave amplitude increased at 4 week after cholecystectomy;2. Dense bodies in smooth muscles increased in group D compared with group A; the protein expression of MHC increased at 2, 4, 8 week after cholecystectomy (P <0.01). 3. Compared with control group, the mRNA expression of CnAβincreased at 4 week after cholecystectomy (P <0.01), but decreased at 8 week compared with 4 week. The protein expression of CnAβincreased at 2, 4 and 8 week after cholecystectomy (P <0.01). There is no difference in mRNA expression and protein expression of CnAαin compared with control group.Conclusion1. The motor function of SO was enhanced after cholecystectomy.2. The ultrastructure of SO cell changed and the protein expression of MHC increased after cholecystectomy.The increase of CnAβmight play a role in the increase of MHC after cholecystectomy. This may be one molecular mechanism that SOD is more frequently recognized in postcholecystectomy patients.
|
PDF Full Text Request