This Article Full Text Full Text (PDF) Services Download to citation manager PubMed PubMed Citation

Effect of Aging and Obesity on Insulin Responsiveness and Glut-4 Glucose Transporter Content in Skeletal Muscle of Fischer 344 x Brown Norway Rats

^a Division of Geriatric Medicine, Department of Internal Medicine
^b Institute of Gerontology, University of Michigan, Ann Arbor
^c Geriatric Research, Education, and Clinical Center, Department of Veterans Affairs Medical Center, Ann Arbor, Michigan
^d The Department of Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts

Lisa M. Larkin, Geriatrics Center, 5302 CCGCB, 1500 East Medical Center Drive, University of Michigan, Ann Arbor, MI 48109-0940 E-mail: llarkin{at}umich.edu.

Decision Editor: Edward Masoro, PhD

This study investigated the metabolic changes with age in the Fischer 344 x Brown Norway rat and its suitability as an animal model of postmaturational insulin resistance. Specifically, we determined whether an age-associated decrease in glucose disposal is associated with diminished whole body insulin responsiveness and/or a decrease in glucose transporter (GLUT-4) protein and mRNA content in medial gastrocnemius muscle of male Fischer 344 x Brown Norway rats of ages 8, 18, and 28 months. Fasting plasma glucose was unchanged with age. There was a significant age effect on visceral adiposity, fasting plasma insulin levels, insulin responsiveness, and GLUT-4 protein content. Insulin responsiveness and GLUT-4 protein were lower in the 18-month-old rats than in the 8-month-old rats. The findings of age-associated increases in visceral adiposity and insulin resistance, and decreases in GLUT-4 in the Fisher 344 x Brown Norway rat, suggest that this rat strain may be an appropriate model for studying the effects of aging on glucose homeostasis.