title: The role of the endocrine system in feeding-induced tissue-specific circadian entrainment.
abstract: The circadian clock is entrained to environmental cycles by external cue-mediated phase adjustment. Although the light input pathway has been well defined, the mechanism of feeding-induced phase resetting remains unclear. The tissue-specific sensitivity of peripheral entrainment to feeding suggests the involvement of multiple pathways, including humoral and neuronal signals. Previous in vitro studies with cultured cells indicate that endocrine factors may function as entrainment cues for peripheral clocks. However, blood-borne factors that are well characterized in actual feeding-induced resetting have yet to be identified. Here, we report that insulin may be involved in feeding-induced tissue-type-dependent entrainment in vivo. In ex vivo culture experiments, insulin-induced phase shift in peripheral clocks was dependent on tissue type, which was consistent with tissue-specific insulin sensitivity, and peripheral entrainment in insulin-sensitive tissues involved PI3K- and MAPK-mediated signaling pathways. These results suggest that insulin may be an immediate early factor in feeding-mediated tissue-specific entrainment.
authors.affiliation: The Research Institute for Time Studies, Yamaguchi University, 1677-1 Yoshida, Yamaguchi 753-8511, Japan.
authors.forename: Miho
authors.initials: M
authors.lastname: Sato
authors.affiliation: The Research Institute for Time Studies, Yamaguchi University, 1677-1 Yoshida, Yamaguchi 753-8511, Japan.
authors.forename: Mariko
authors.initials: M
authors.lastname: Murakami
authors.affiliation: Department of Cardiovascular Medicine, Saga University, 5-1-1 Nabeshima, Saga 849-8501, Japan.
authors.forename: Koichi
authors.initials: K
authors.lastname: Node
authors.affiliation: The Research Institute for Time Studies, Yamaguchi University, 1677-1 Yoshida, Yamaguchi 753-8511, Japan.
authors.forename: Ritsuko
authors.initials: R
authors.lastname: Matsumura
authors.affiliation: The Research Institute for Time Studies, Yamaguchi University, 1677-1 Yoshida, Yamaguchi 753-8511, Japan. Electronic address: akashima@yamaguchi-u.ac.jp.
authors.forename: Makoto
authors.initials: M
authors.lastname: Akashi
mesh_terms: D016475:3T3 Cells; D000818:Animals; D045744:Cell Line, Tumor; D057906:Circadian Clocks; D004435:Eating; D004703:Endocrine System / Q000378:metabolism* / Q000502:physiology; D006801:Humans; D007328:Insulin / Q000378:metabolism; D020935:MAP Kinase Signaling System; D051379:Mice; D009928:Organ Specificity; D056950:Period Circadian Proteins / Q000235:genetics / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism
chemical_list: D007328:Insulin; C513312:Per2 protein, mouse; D056950:Period Circadian Proteins; D019869:Phosphatidylinositol 3-Kinases