title: Overexpression of Insulin Degrading Enzyme could Greatly Contribute to Insulin Down-regulation Induced by Short-Term Swimming Exercise.
abstract: Exercise training is highly correlated with the reduced glucose-stimulated insulin secretion (GSIS), although it enhanced insulin sensitivity, glucose uptake and glucose transporter expression to reduce severity of diabetic symptoms. This study investigated the impact of short-term swimming exercise on insulin regulation in the Goto-Kakizaki (GK) rat as a non-obese model of non-insulin-dependent diabetes mellitus. Wistar (W/S) and GK rats were trained 2 hours daily with the swimming exercise for 4 weeks, and then the changes in the metabolism of insulin and glucose were assessed. Body weight was markedly decreased in the exercised GK rats compare to their non-exercised counterpart, while W/S rats did not show any exercise-related changes. Glucose concentration was not changed by exercise, although impaired glucose tolerance was improved in GK rats 120 min after glucose injection. However, insulin concentration was decreased by swimming exercise as in the decrease of GSIS after running exercise. To identify the other cause for exercise-induced insulin down-regulation, the changes in the levels of key factors involved in insulin production (C-peptide) and clearance (insulin-degrading enzyme; IDE) were measured in W/S and GK rats. The C-peptide level was maintained while IDE expression increased markedly. Therefore, these results showed that insulin down-regulation induced by short-term swimming exercise likely attributes to enhanced insulin clearance via IDE over-expression than by altered insulin production.
authors.affiliation: Department of Laboratory Animal Resources, National Institute of Food and Drug Evaluation, Seoul, Republic of Korea.
authors.forename: Min Sun
authors.initials: MS
authors.lastname: Kim
authors.forename: Jun Seo
authors.initials: JS
authors.lastname: Goo
authors.forename: Ji Eun
authors.initials: JE
authors.lastname: Kim
authors.forename: So Hee
authors.initials: SH
authors.lastname: Nam
authors.forename: Sun Il
authors.initials: SI
authors.lastname: Choi
authors.forename: Hye Ryun
authors.initials: HR
authors.lastname: Lee
authors.forename: In Sik
authors.initials: IS
authors.lastname: Hwang
authors.forename: Sun Bo
authors.initials: SB
authors.lastname: Shim
authors.forename: Seung Wan
authors.initials: SW
authors.lastname: Jee
authors.forename: Su Hae
authors.initials: SH
authors.lastname: Lee
authors.forename: Chang Joon
authors.initials: CJ
authors.lastname: Bae
authors.forename: Jung Sik
authors.initials: JS
authors.lastname: Cho
authors.forename: Jun Yong
authors.initials: JY
authors.lastname: Cho
authors.forename: Dae Youn
authors.initials: DY
authors.lastname: Hwang