Abstract
In our previous study, we presented a significant difference in neuropeptide Y (NPY) mRNA in the arcuate nucleus of the hypothalamus (ARC) between food-restricted and exercising OLETF rats. However, we found no significant differences between ad lib control and exercising rats. It is well known that Golden Syrian Hamsters have a higher activity level than rats and they have strictly distinguished circadian rhythms in running activity. For those reasons, we expected that the regulation factors of appetite behavior will be changed obviously in exercising hamsters. Moreover, hamsters have a hoarding habit, which reflects their long-term appetite. Therefore, we attempted to use the hamsters in this study. As a result, exercising hamsters showed strictly distinguished circadian rhythms in running activity, and we could find the low appetite behaviors indicated by the decreases in eating and hoarding volume of food. Leptin showed a marked decrease in exercising hamsters compared to ad lib controls. No significant difference was found in leptin receptors mRNA in the ARC. Also, in accordance with our expectations, NPY mRNA showed a significant decrease in exercising hamsters compared to ad lib controls. Therefore, we speculate that one of the mechanism leading to exercise-induced appetite inhibition is a decrease in NPY in the ARC. [J Physiol Sci. 2007;57 Suppl:S186]
