Glucosamine (GlcN), which has been reported to induce insulin resistance (IR), is a popular nutritional supplement used to treat osteoarthritis in menopausal women. We previously demonstrated that GlcN treatment caused IR in ovariectomized rats by reducing the expression of glucose transport protein subtype 4 (GLUT-4) in skeletal muscle. In the present study, we hypothesized that endurance exercise training can reverse GlcN-induced IR.
Fifty female rats were randomly divided into five groups with 10 rats in each group: (1) sham-operated group; (2) sham-operated group with GlcN treatment for 14 days; (3) ovariectomy (OVX) group; (4) OVX with GlcN treatment; and (5) OVX with GlcN treatment followed by exercise training (running program) for 8 weeks.
Fasting plasma glucose increased in the OVX + GlcN group, and fasting plasma insulin and the homeostasis model assessment-insulin resistance (HOMA-IR) were significantly higher only in this group. After the rats received exercise training for 8 weeks, no increase in the fasting plasma glucose, insulin, or HOMA-IR was observed. In an intraperitoneal glucose tolerance test, the plasma glucose, plasma insulin, HOMA-IR, and glucose-insulin index were significantly elevated only in the OVX with GlcN treatment group. However, the plasma glucose, plasma insulin, HOMA-IR, and glucose-insulin index decreased after exercise training for 8 weeks, implying that GlcN-induced IR in OVX rats could be reversed through exercise. A histological analysis revealed that exercise training can reduce islet hypertrophy and maintain GLUT-4 in skeletal muscle.
Exercise training can alleviate IR in OVX rats treated with GlcN. Islet hyperplasia was subsequently prevented. Preserving GLUT-4 expression may be one of the mechanisms by which exercise prevents IR.
1Department of Orthopedics, Kaohsiung Municipal Ta-Tung Hospital, Kaohsiung City, Taiwan
2Department of Orthopedics, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung, Taiwan
3Orthopaedic Research Center, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan
4Departments of Orthopedics, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan
5Institute of Physical Education, Health and Leisure Studies, National Cheng Kung University, Tainan, Taiwan
6Department of Physiology, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan
7Department of Anatomy, School of Medicine, China Medical University, Taichung, Taiwan
8Graduate Institute of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan
9Department of Obstetrics and Gynecology, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, Tainan, Taiwan.
Address correspondence to: Lin Kang, MD, PhD, Department of Obstetrics and Gynecology, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, No. 138, Sheng-Li Road, Tainan 70428, Taiwan. E-mail: firstname.lastname@example.org
Received 7 July, 2016
Revised 26 October, 2016
Accepted 26 October, 2016
C.-H.C. and T.-H.H contributed equally.
Funding/support: This study was supported in part by the National Cheng Kung University Hospital (NCKUH-10203008), Kaohsiung Medical University Hospital (KMUH103-3R38), Kaohsiung Medical University (KMU-TP104B09, KMU-DK105009), and Taiwan and Ministry of Science and Technology (MOST 103-2314-B-006-072-) (MOST 104-2314-B-037-032-MY3) (104-2314-B-006-071-MY2) of Taiwan.
Financial disclosure/conflicts of interest: None reported.