title: Effect of treadmill exercise on interleukin-15 expression and glucose tolerance in zucker diabetic Fatty rats.
abstract: BACKGROUND
  Interleukin-15 (IL-15), a well-known myokine, is highly expressed in skeletal muscle and is involved in muscle-fat crosstalk. Recently, a role of skeletal muscle-derived IL-15 in the improvement of glucose homeostasis and insulin sensitivity has been proposed. However, little is known regarding the influence of endurance training on IL-15 expression in type 2 diabetic skeletal muscles. We investigated the effect of endurance exercise training on glucose tolerance and IL-15 expression in skeletal muscles using type 2 diabetic animal models.
  
  
  METHODS
  MALE ZUCKER DIABETIC FATTY (ZDF) AND ZDF LEAN CONTROL (ZLC) RATS WERE RANDOMLY DIVIDED INTO THREE GROUPS: sedentary ZLC, sedentary ZDF (ZDF-Con), and exercised ZDF (ZDF-Ex). The ZDF-Ex rats were forced to run a motor-driven treadmill for 60 minutes once a day 5 times per week for 12 weeks. Intraperitoneal glucose tolerance test (IPGTT) was performed after 12 weeks. Expression of IL-15 was measured using ELISA in extracted soleus (SOL) and gastrocnemius medial muscles.
  
  
  RESULTS
  After 12 weeks of treadmill training, reduction of body weight was observed in ZDF-Ex compared to ZDF-Con rats. Glucose tolerance using IPGTT in diabetic rats was significantly improved in ZDF-Ex rats. Furthermore, the expression of IL-15 was significantly increased (P<0.01) only in the SOL of ZDF-Ex rats compared to ZDF-Con. Additionally, IL-15 expression in SOL muscles was negatively correlated with change of body weight (R=-0.424, P=0.04).
  
  
  CONCLUSIONS
  The present study results suggest that 12 weeks of progressive endurance training significantly improved glucose tolerance with concomitant increase of IL-15 expression in SOL muscles of type 2 diabetic rats.
authors.affiliation: Health and Exercise Science Laboratory, The Institute of Sports Science, Seoul National University, Seoul, Korea.
authors.forename: Hee-Jae
authors.initials: HJ
authors.lastname: Kim
authors.forename: Jae Young
authors.initials: JY
authors.lastname: Park
authors.forename: Seung Lyul
authors.initials: SL
authors.lastname: Oh
authors.forename: Yong-An
authors.initials: YA
authors.lastname: Kim
authors.forename: Byunghun
authors.initials: B
authors.lastname: So
authors.forename: Je Kyung
authors.initials: JK
authors.lastname: Seong
authors.forename: Wook
authors.initials: W
authors.lastname: Song
keywords: Exercise; Glucose intolerance; Interleukin-15; Rats, Zucker; Treadmill