Modulation of Core Body Temperature by Amino Acids

(Young Investigator Award of JSNFS (2010))

Abstract

Anesthetics impair core body temperature (T_core) homeostasis, resulting in a reduction of T_core during surgery that is associated with a poorer postoperative outcome. We attempted to prevent such a decrease of T_core in rats by infusion of a solution of amino acids (AAs) during anesthesia. The infusion enhanced muscle protein synthesis accompanied by obvious increases in plasma insulin and translation initiation activities in comparison with the conscious state. The increased plasma insulin contributed to the linkage acceleration of muscle protein synthesis, themogenesis and heat storage by AAs. The AAs also enhanced myofibrillar protein breakdown. These findings provide supportive evidence for the connection that enhancement of protein turnover by AAs contributes to T_core modification. Branched chain amino acids play an important role in heat accumulation, and isoleucine then contributes to control of glucose and energy metabolism. We also demonstrated that dietary protein modulates circadian T_core fluctuation differently in rats during the dark and light phases. These findings suggest that AAs contribute considerably to T_core modification, which is an important vital sign.