Cellular and biochemical features of skeletal muscle in obese Yucatan minipigs.
OBJECTIVE
To examine cellular and biochemical features of skeletal muscle in response to dietary-induced obesity in a novel Yucatan minipig model of childhood obesity.


METHODS
From 4 to 16 months of age, minipigs were fed either a recommended human-type diet (NF; n = 4) or were overfed a western-type diet with saturated fat and high-glycemic index carbohydrates (OF, n = 4). Muscle samples (biceps femoris) were histochemically stained for the identification of intramuscular adipocytes, intramyocellular lipid aggregates (oil red O), and myofiber types (myosin ATPase, succinate dehydrogenase). Gene expressions and/or activities of factors involved in lipogenesis, lipolysis, or energetic metabolism were quantified in muscle.


RESULTS
Cross-sectional areas of myofibers paralleled pig body weight (r = 0.86, p < 0.01). The size of intramuscular adipocytes, the relative proportion of oil red O-stained fibers, and total muscle lipid content tended (p < or = 0.10) to increase in response to OF diet. Hormone-sensitive lipase, carnitine palmityl transferase-I, and uncoupling protein 2 mRNA levels were lower (p < 0.05) in OF pigs than in NF pigs. Activities of beta-hydroxyacyl-coenzyme A dehydrogenase and citrate synthase assessing post-carnitine palmityl transferase I events and the proportion of oxidative myofibers were not altered by OF diet. Activity and gene expression of fatty acid synthase were lower (p < 0.02) in OF pigs than in NF pigs.


CONCLUSIONS
Overfeeding in Yucatan minipigs reduced the expression levels of three catabolic steps in skeletal muscle that are involved also in the etiology of human obesity.
Guillerm-Regost
Christelle
C
Institut National de la Recherche Agronomique/AgroCampus Rennes, Unité Mixte de Recherche, Livestock Production Systems, Animal and Human Nutrition, Saint Gilles, France.
Louveau
Isabelle
I
Sébert
Sylvain P
SP
Damon
Marie
M
Champ
Martine M
MM
Gondret
Florence
F
D017667:Adipocytes / Q000378:metabolism / Q000473:pathology; D000818:Animals; D001835:Body Weight / Q000502:physiology; D004040:Dietary Carbohydrates / Q000008:administration & dosage; D004041:Dietary Fats / Q000008:administration & dosage; D064429:Fatty Acid Synthases / Q000378:metabolism; D015870:Gene Expression / Q000235:genetics; D006003:Glycogen / Q000378:metabolism; D006801:Humans; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D008055:Lipids / Q000032:analysis; D050155:Lipogenesis / Q000235:genetics; D018485:Muscle Fibers, Skeletal / Q000378:metabolism / Q000473:pathology; D018482:Muscle, Skeletal / Q000378:metabolism* / Q000473:pathology*; D009765:Obesity / Q000209:etiology / Q000503:physiopathology*; D047495:PPAR gamma / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051780:Sterol Regulatory Element Binding Protein 1 / Q000235:genetics; D050151:Subcutaneous Fat / Q000378:metabolism; D013552:Swine; D013556:Swine, Miniature
D004040:Dietary Carbohydrates; D004041:Dietary Fats; D008055:Lipids; D047495:PPAR gamma; D012333:RNA, Messenger; C497388:Srebf1 protein, mouse; D051780:Sterol Regulatory Element Binding Protein 1; D006003:Glycogen; D007770:L-Lactate Dehydrogenase; D064429:Fatty Acid Synthases