title: Changes in photoperiod alter Glut4 expression in skeletal muscle of C57BL/6J mice.
abstract: Seasonal changes in photoperiod influence body weight and metabolism in mice. Here, we examined the effect of changes in photoperiod on the expression of glucose transporter genes in the skeletal muscle and adipose tissue of C57BL/6J mice. Glut4 expression was lower in the gastrocnemius muscle of mice exposed to a short-duration day (SD) than those to a long-duration day (LD), with accompanying changes in GLUT4 protein levels. Although Glut4 expression in the mouse soleus muscle was higher under SD than under LD, GLUT4 protein levels remained unchanged. To confirm the functional significance of photoperiod-induced changes in Glut4 expression, we checked for variations in insulin sensitivity. Blood glucose levels after insulin injection remained high under SD, suggesting that the mice exposed to SD showed lower sensitivity to insulin than those exposed to LD. We also attempted to clarify the relationship between Glut4 expression and physical activity in the mice following changes in photoperiod. Locomotor activity, as detected via infrared beam sensor, was lower under SD than under LD. However, when we facilitated voluntary activity by using running wheels, the rotation of wheels was similar for both groups of mice. Although physical activity levels were enhanced due to running wheels, Glut4 expression in the gastrocnemius muscle remained unchanged. Thus, variations in photoperiod altered Glut4 expression in the mouse skeletal muscle, with subsequent changes in GLUT4 protein levels and insulin sensitivity; these effects might be independent of physical activity.
authors.affiliation: Laboratory of Regulation in Metabolism and Behavior, Faculty of Agriculture, Kyushu University, Hakozaki 6-10-1, Higashi-ku, Fukuoka 812-8581, Japan.
authors.forename: Ayako
authors.initials: A
authors.lastname: Tashiro
authors.affiliation: Laboratory of Regulation in Metabolism and Behavior, Faculty of Agriculture, Kyushu University, Hakozaki 6-10-1, Higashi-ku, Fukuoka 812-8581, Japan.
authors.forename: Satomi
authors.initials: S
authors.lastname: Shibata
authors.affiliation: Laboratory of Regulation in Metabolism and Behavior, Faculty of Agriculture, Kyushu University, Hakozaki 6-10-1, Higashi-ku, Fukuoka 812-8581, Japan.
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Takai
authors.affiliation: Laboratory of Regulation in Metabolism and Behavior, Faculty of Agriculture, Kyushu University, Hakozaki 6-10-1, Higashi-ku, Fukuoka 812-8581, Japan.
authors.forename: Tatsuhiro
authors.initials: T
authors.lastname: Uchiwa
authors.affiliation: Laboratory of Regulation in Metabolism and Behavior, Faculty of Agriculture, Kyushu University, Hakozaki 6-10-1, Higashi-ku, Fukuoka 812-8581, Japan.
authors.forename: Mitsuhiro
authors.initials: M
authors.lastname: Furuse
authors.affiliation: Laboratory of Regulation in Metabolism and Behavior, Faculty of Agriculture, Kyushu University, Hakozaki 6-10-1, Higashi-ku, Fukuoka 812-8581, Japan. Electronic address: syasuo@brs.kyushu-u.ac.jp.
authors.forename: Shinobu
authors.initials: S
authors.lastname: Yasuo
mesh_terms: D000818:Animals; D005786:Gene Expression Regulation; D005947:Glucose / Q000378:metabolism; D051275:Glucose Transporter Type 4 / Q000032:analysis / Q000235:genetics* / Q000378:metabolism; D007328:Insulin / Q000378:metabolism; D007333:Insulin Resistance; D008297:Male; D008810:Mice, Inbred C57BL; D018482:Muscle, Skeletal / Q000378:metabolism / Q000502:physiology*; D017440:Photoperiod; D010805:Physical Conditioning, Animal; D012420:Running
chemical_list: D051275:Glucose Transporter Type 4; D007328:Insulin; C495693:Slc2a4 protein, mouse; D005947:Glucose
keywords: Gastrocnemius muscle; Glucose transporter; Insulin sensitivity; Locomotor activity; Photoperiodism; Running wheel