New Roles of Ghrelin, Appetite Regulating Hormone, in the Motivation for Voluntary Exercise at the Reset Time of the Circadian Rhythm
【Supercategory：7. DESCENTE SPORTS SCIENCE Subcategory：7.39 Vol.39】
ABSTRACT
Ghrelin is involved in the brain reward circuits via dopamine neurons related to motivational properties. Here, we showed the relevance of ghrelin as an initiator of voluntary exercise in ghrelin knockout (GKO) mice. The plasma ghrelin concentration showed a bimodal diurnal rhythm with peaks at the beginning and end of the dark phase in the wild type (WT) mice. Although predominant increases in wheel running activity were observed accordant to both peaks of plasma ghrelin in the WT mice, those were severely attenuated in the GKO mice. A single injection of ghrelin receptor agonist brought about marked enhancement of wheel running activity, in contrast to no effect by the continuous administration. The brain dopamine level was attenuated in GKO mice compared to that in WT mice. These findings suggested that the surge in ghrelin should play a crucial role in the motivation for voluntary exercise via the central hedonic dopamine system.
DESCENTE SPORTS SCIENCE Vol.39/THE DESCENTE AND ISHIMOTO MEMORIAL FOUNDATION FOR THE PROMOTION SPORTS SCIENCE
Ghrelin is involved in the brain reward circuits via dopamine neurons related to motivational properties. Here, we showed the relevance of ghrelin as an initiator of voluntary exercise in ghrelin knockout (GKO) mice. The plasma ghrelin concentration showed a bimodal diurnal rhythm with peaks at the beginning and end of the dark phase in the wild type (WT) mice. Although predominant increases in wheel running activity were observed accordant to both peaks of plasma ghrelin in the WT mice, those were severely attenuated in the GKO mice. A single injection of ghrelin receptor agonist brought about marked enhancement of wheel running activity, in contrast to no effect by the continuous administration. The brain dopamine level was attenuated in GKO mice compared to that in WT mice. These findings suggested that the surge in ghrelin should play a crucial role in the motivation for voluntary exercise via the central hedonic dopamine system.
DESCENTE SPORTS SCIENCE Vol.39/THE DESCENTE AND ISHIMOTO MEMORIAL FOUNDATION FOR THE PROMOTION SPORTS SCIENCE
| Researcher | Hiroharu Mifune*1, Yuji Tajiri*2, Ryouichi Mitsuzono*3 |
|---|---|
| University or institution | *1 Institute of Animal Experimentation, Kurume University School of Medicine, *2 Division of Endocrinology, Kurume University, *3 Institute of Health and Sports Science, Kurume University |
Keywords
Ghrelin, Exercise Motivation, Circadian Rhythm, Ghrelin Knockout Mouse, Appetite Regulating Hormone