Diet, not aging, causes skeletal muscle insulin resistance.
The purpose of this study was to compare the effects of raising female Fischer rats on a low-fat, high-complex-carbohydrate diet (LFCC) versus a high-fat, sucrose diet (HFS) on serum glucose and insulin as well as skeletal muscle glucose transport. No significant differences were observed between 6- and 24-month-old rats raised on the LFCC diet for serum glucose (3.6 +/- 0.1 vs. 3.7 +/- 0.2 mM) and insulin (88 +/- 6 vs. 98 +/- 10 pM) or for basal (35 +/- 3 vs. 39 +/- 6 pmol/mg protein/15 s) or insulin-stimulated (74.2 +/- 7.6 vs. 69.4 +/- 3.8 pmol/mg protein/15 s) glucose transport. These data indicate that aging per se does not lead to insulin resistance. When the 24-month-old animals raised on the HFS diet were compared with those on the LFCC diet, major differences were observed. Fasting serum insulin was significantly higher in the HFS group (437 +/- 118 vs. 98 +/- 10 pM) and insulin-stimulated glucose transport was significantly reduced (52.5 +/- 3.7 vs. 69.4 +/- 3.8 pmol/mg protein/15 s). Fasting glucose (3.7 +/- 0.2 vs. 3.6 +/- 0.1 mM) and basal glucose transport (38 +/- 6 vs. 39 +/- 6 pmol/mg protein/15 s) were unchanged. These results indicate that diet and not aging per se caused insulin resistance.
Barnard
R J
RJ
Department of Physiological Science, University of California, Los Angeles 90024-1527, USA.
Youngren
J F
JF
Martin
D A
DA
D000375:Aging / Q000378:metabolism*; D000818:Animals; D001693:Biological Transport, Active; D001786:Blood Glucose / Q000378:metabolism; D004032:Diet / Q000009:adverse effects*; D004040:Dietary Carbohydrates / Q000008:administration & dosage; D004041:Dietary Fats / Q000008:administration & dosage; D005215:Fasting / Q000378:metabolism; D005260:Female; D005947:Glucose / Q000378:metabolism; D007328:Insulin / Q000097:blood; D007333:Insulin Resistance / Q000502:physiology; D018482:Muscle, Skeletal / Q000378:metabolism; D051381:Rats; D011916:Rats, Inbred F344; D012508:Sarcolemma / Q000378:metabolism
D001786:Blood Glucose; D004040:Dietary Carbohydrates; D004041:Dietary Fats; D007328:Insulin; D005947:Glucose