Cholecystokinin (CCK) has been found to express in various regions of the central nervous system, including hypothalamus. However, it is not clear what are the functional roles of CCK expressed in the hypothalamus in the regulation of body weight. In this study, we examined the expression of CCK mRNA expression in the hypothalamus of chronic high-fat diet-induced obese (DIO), obese-resistant (DR) and low-fat fed (LF) mice. The expression of CCK mRNA in the hypothalamic nuclei was examined using in situ hybridization technique.
The results showed that DIO mice had significantly higher body weight and food intake than DR and LF mice. DR mice had significantly higher CCK mRNA expression than the DIO (p=0.019) and LF (p=0.021) mice in the arcuate hypothalamic nucleus (Arc). However, DIO mice did not significantly differ from LF mice in CCK mRNA expression in the Arc (p=0.989). There was no significantly difference in CCK mRNA expression in the dorsomedial hypothalamic nucleus, ventromedial hypothalamic nucleus, and ventral tegmental area among DIO, DR and LF mice.
In conclusion, this study has shown that DIO mice had no change in CCK mRNA expression following a high-fat diet. Conversely, DR mice had a higher CCK mRNA expression in the Arc in respond to high-fat diet, which may contribute to resistance of obesity development.