Evaluation of postprandial thermal feeling in mice using a behavioral thermoregulation analysis: Differences in meat species and their fractions

Classification of the thermal nature of meat in traditional Chinese medicine (TCM) varies depending on the meat species and their fractions. The objectives of this study were to establish an experimental system to evaluate postprandial thermal feeling based on behavioral thermoregulation, investigate it among different meat species and their fractions, and clarify the relationship between their thermal nature and the active meat constituents that affect thermal feeling. Freeze-dried meat, defatted meat, and extracted fat were prepared from horse meat, chicken, pork, beef, mutton, and venison. After feeding, mice were placed in an elongated chamber equipped with a continuous thermogradient floor. An obvious peak in the cumulative staying time at the mouse's preferred temperature was observed after 30 min, and the postprandial thermal feeling was evaluated by examining the preferred temperatures. As a result, purified meat proteins were not considered to affect postprandial thermal feeling among meat species. In contrast, the ethanol and water extracts of defatted horse meat induced a “cool feeling,” and the extracts of other meat species induced a “warm feeling.” Chicken and pork fat induced a cool feeling, whereas beef and mutton fat induced a warm feeling. Additionally, certain dose-dependent constituent(s) in these fats affected the postprandial thermal feeling. Using the established evaluation system, it was concluded that the extract and fat in meat are involved in the postprandial thermal feeling, and the thermal nature of the meat in TCM depends not only on animal-specific components but also on their contents.