The Construction Of CCK Transgenic Mice And Exploration In Its Effects On Food Intake Behavior

Cholecystokinin(CCK) is a peptide, which distributed widely throughout the gastrointestinal tract and the central nervous system, and has a number of physiological effects. In addition to gallbladder contraction, Cholecystokinin also regulates enzyme secretion and growth of pancreas, intestinal motility, satiety signalling and the inhibition of gastric acid secretion. As one of the most abundant neuropeptide in the brain, Cholecystokinin take part in some physiological process in the central nervous system and dose have some important role, such as food consumption, anxiety, regulation of blood pressure and memory, and so on. However, it is not very clearly about the detailed mechanisms of its functions. Besides, there are controversies about whether CCK can regulate the long-term food consumption of animals by its functions in brain; whether CCK can protect neurons and improve the memory? In addition, researchers are now trying to find out the presumed relationship between CCK and some central neuron diseases like Parkinson's disease and Schizophrenia. Nowadays, people focus there research on the function of various CCK peptide and receptors. However, there is no CCK transgenic mouse until now.To do further research into the definite function of CCK in central nervous system, we use the neuron-specific promoter PDGF to construct transgenic mice and detect the expression of the exogenous gene. The whole project had mainly three parts: the CCK cDNA was cloned and the expression vector was constructed; the expression of the vector was detected in SH-SY5Y neuroblastoma cells; the expression of exogenous gene was detected in transgenic mice and the function of CCK on food intake was explored.CCK cDNA was cloned and inserted into the expression vector under control of PDGF promoter. The expression vector was transient transfected into SH-SY5Y neuroblastoma cells and Western Blot showed its expression in vitro. Cut out the fragment containing PDGF promoter, CDS of CCK and PolyA and prepare it for the microinjection. Three out of thirteen mice were confirmed to be positive transgenic mice. Western Blot indicated that there are high expression of CCK in the brain and intestine. The expression levels of CCK in the brain tissue of three founders was detected with Western Blot and compared to the wild type mouse. Results showed that there were expressions of the exogenous gene in all the three founders. The expression levels of CCK in brains of founder 8~#,12~# and 20~# were one,one and two times higher respectively compared to that of the wild type mouse. Mice were divided into transgenic arid control groups and were given normal and high fat diet. Preliminary experiment shows that when given normal diet, body weights of male transgenic mice were lower compared to control mice (27.61±1.67g vs 30.02±1.04g, P＜0.05); and female transgenic mice show same trend(21.48±0.41g vs 22.00±1.02g, P=0.364); when given high fat diet, body weight of transgenic female mice were lower compared to control mice (21.83±0.54g vs 23.36±1.09g, P＜0.05), and male transgenic mice show same trend (27.56±2.04g vs 29.13±1.47g, P=0.144)。Detection of food and water intake of every groups showed that: under normal diet, male transgenic group consume less food compared to control group, female consume more; under high fat diet, transgenic group consume more food compared to control group. As for water intake, there is no obvious difference among groups. The results suggest that CCK has effect on food consumption of mice. It could be an important peptide to regulate food intake and body weight of mice.