title: Effect of aging and obesity on insulin responsiveness and glut-4 glucose transporter content in skeletal muscle of Fischer 344 x Brown Norway rats.
abstract: 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.
authors.affiliation: Division of Geriatric Medicine, Department of Internal Medicine, University of Michigan, Ann Arbor 48109-0940, USA. llarkin@umich.edu
authors.forename: L M
authors.initials: LM
authors.lastname: Larkin
authors.forename: T H
authors.initials: TH
authors.lastname: Reynolds
authors.forename: M A
authors.initials: MA
authors.lastname: Supiano
authors.forename: B B
authors.initials: BB
authors.lastname: Kahn
authors.forename: J B
authors.initials: JB
authors.lastname: Halter
mesh_terms: D000273:Adipose Tissue / Q000473:pathology; D000375:Aging / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D005947:Glucose / Q000378:metabolism; D051275:Glucose Transporter Type 4; D006706:Homeostasis; D007328:Insulin / Q000097:blood; D007333:Insulin Resistance / Q000502:physiology*; D008297:Male; D023421:Models, Animal; D009004:Monosaccharide Transport Proteins / Q000235:genetics / Q000378:metabolism*; D009124:Muscle Proteins; D018482:Muscle, Skeletal / Q000378:metabolism*; D009765:Obesity / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D011914:Rats, Inbred BN; D011916:Rats, Inbred F344
chemical_list: D001786:Blood Glucose; D051275:Glucose Transporter Type 4; D007328:Insulin; D009004:Monosaccharide Transport Proteins; D009124:Muscle Proteins; D012333:RNA, Messenger; C495694:Slc2a4 protein, rat; D005947:Glucose