| Research Abstract |
Cholecystokinin (CCK) is an important gastrointestinal hormone as well as neurotransmitter. Two types of CCK receptors (type A and type B) have been identified. The CCK-A receptor is known to be involved in satiety, food intake and behavior and the B receptor to be involved in anxiety. As we recently raised CCK-A, -B and AB receptor knockout mice, the role of these receptors was determined.
CCK-BR(-/-) and AR(-/-)BR(-/-) mice showed increased anxiety states compared with CCK-AR(+/+)BR(+/+) and AR(-/-) mice. Previous reports showed that panic attack and anxiety could be induced by CCK-4, which predominantly bound CCK-BR. Our observation was not compatible for the previous report. Further study is necessary.
The daily energy intake and energy expenditure were significantly higher in CCK BR(-/-) and CCK-AR(-/-)BR(-/-) mice than CCK-AR(-/-) and wild-type [CCKAR(+/+)BR(+/+)] mice. The ratios of liver and kidneys per body weight (g-kg) were significantly higher in CCKAR(-/-)BR(-/-) mice than wild-type mice. Energy metabolism and energy turnover were increased under the condition of disruption of CCK-BR gene, although the real mechanism is unknown.
Gastric emptying was not delayed in CCK-AR(-/-) mice. Gastric emptying was enhanced in CCK-BR(-/-) and AR(-/-)BR(-/-) mice. However, administration of atropine significantly inhibited gastric emptying in all mice. CCK-8 delayed gastric emptying in CCK-AR(+/+)BR(+/+) and BR(-/-) mice, but not in CCK-AR(-/-) and AR(-/-)BR(-/-) mice.
In mice, CCK, acetylcholine, and GRP could stimulate amylase release from the pancreas, whereas only CCK could induce gallb ladder contration.
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