Lipid metabolism and cellular features of skeletal muscle and subcutaneous adipose tissue in pigs differing in IGF-II genotype.
In pigs, a paternally (pat) imprinted mutation in the IGF-II gene is associated with increased muscle mass and decreased backfat thickness. The aim of this study was to determine whether this mutation influenced cellular, biochemical and metabolic features of skeletal muscle and adipose tissue. Muscle (trapezius) and subcutaneous adipose tissue (SCAT) were collected from pigs (106kg) carrying (Qpat, n=6) or not carrying (qpat, n=7) the mutation. Adipocytes were isolated from those tissues by collagenase treatment. Lipid content and activity of lipogenic enzymes were determined using standard assays. Gene expression levels were determined by real-time PCR. Levels of IGF-II mRNA were higher (P<0.01) in muscle of Qpat than in that of qpat pigs, but they did not differ significantly between the two groups in SCAT. Whereas levels of IGF-I mRNA in muscle were similar in both groups, they were higher (P<0.05) in SCAT of Qpat pigs than in that of qpat pigs. Muscle lipid content and intramuscular adipocyte diameters were not influenced significantly by the IGF-II genotype. In SCAT, the reduction of backfat thickness in Qpat pigs compared with qpat pigs was associated with lower (P<0.05) lipid content and smaller (P<0.05) adipocytes, with no significant genotype-effects on expressions and/or activities of lipogenic enzymes. In summary, our results suggest that the IGF-II mutation altered body composition in pigs by favoring myofiber hypertrophy and repressing adipose cell development in SCAT.
Gardan
Delphine
D
INRA, Unité Mixte de Recherches, Systèmes d'Elevage, Nutrition Animale et Humaine, 35590 Saint Gilles, France.
Gondret
Florence
F
Van den Maagdenberg
Karijn
K
Buys
Nadine
N
De Smet
Stefaan
S
Louveau
Isabelle
I
D017667:Adipocytes / Q000166:cytology / Q000378:metabolism; D000818:Animals; D002452:Cell Count / Q000662:veterinary; D048429:Cell Size; D054890:Fatty Acid Synthase, Type I / Q000235:genetics / Q000378:metabolism; D005260:Female; D015870:Gene Expression; D006651:Histocytochemistry / Q000662:veterinary; D007334:Insulin-Like Growth Factor I / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism; D007335:Insulin-Like Growth Factor II / Q000096:biosynthesis / Q000235:genetics* / Q000378:metabolism*; D050356:Lipid Metabolism / Q000235:genetics*; D008291:Malate Dehydrogenase / Q000235:genetics / Q000378:metabolism; D008297:Male; D018482:Muscle, Skeletal / Q000166:cytology / Q000201:enzymology / Q000378:metabolism*; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D017526:Receptor, IGF Type 1 / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism; D017527:Receptor, IGF Type 2 / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000662:veterinary; D050151:Subcutaneous Fat / Q000166:cytology / Q000201:enzymology / Q000378:metabolism*; D013552:Swine / Q000235:genetics* / Q000378:metabolism*
D012333:RNA, Messenger; D017527:Receptor, IGF Type 2; D007334:Insulin-Like Growth Factor I; D007335:Insulin-Like Growth Factor II; D008291:Malate Dehydrogenase; D054890:Fatty Acid Synthase, Type I; D017526:Receptor, IGF Type 1