Skeletal muscle composition in dietary obesity-susceptible and dietary obesity-resistant rats.
The intent of this study was to determine whether a relationship exists between susceptibility to high-fat diet (HFD)-induced obesity and skeletal muscle fiber type. Forty-four adult male Wistar rats were given ad libitum access to a HFD (60% of calories from fat) for 4 wk. Rats were then grouped into quartiles for total weight gain, and the top-quartile [obesity prone (OP)] rats were compared with the bottom-quartile [obesity resistant (OR)] rats. OP rats gained 1.5 times as much weight as OR rats. OR rats had a significantly higher proportion of type I muscle fibers in the medial head of the gastrocnemius muscle than OP rats both before (determined from a muscle biopsy) and after the HFD feeding period. A greater proportion of type I fibers may be associated with a greater capacity for fat oxidation, which would favor resistance to body fat accumulation. Preexisting differences in muscle fiber composition may play a role in determining susceptibility to dietary obesity.
Abou Mrad
J
J
Department of Pediatrics, Vanderbilt University, Nashville, Tennessee 37232.
Yakubu
F
F
Lin
D
D
Peters
J C
JC
Atkinson
J B
JB
Hill
J O
JO
D000818:Animals; D001823:Body Composition; D001835:Body Weight; D004032:Diet; D004198:Disease Susceptibility; D008297:Male; D009132:Muscles / Q000473:pathology*; D009765:Obesity / Q000209:etiology* / Q000473:pathology; D051381:Rats; D011919:Rats, Inbred Strains