Childhood obesity and insulin resistance in a Yucatan mini-piglet model: putative roles of IGF-1 and muscle PPARs in adipose tissue activity and development.
OBJECTIVE
To explore metabolic and cellular modifications induced during childhood obesity, in a novel animal model of obese mini-piglets.


METHODS
A total of 10 four-month old Yucatan mini-pigs were followed from prepuberty to adulthood. Animals were divided into two groups. The first one had been overfed (OF) a western-type diet and the second one had been normally fed a control recommended human-type diet (NF).


METHODS
Plasma insulin-like growth factor 1 (IGF-1), insulin, leptin, nonesterified fatty acids, triglycerides (TGs) and glucose were determined at sexual maturity and at young adulthood. Quantitative gene expressions of peroxysome-proliferator-activated receptors (PPARs), glucose transporter 4, insulin receptor, IGF-1, leptin and interleukin-6 (IL-6) in skeletal muscle, adipose tissue and liver were also measured at both stages. Adult insulin sensitivity was measured via euglycaemic-hyperinsulinaemic clamps.


RESULTS
Increased body weight in adult OF pigs was associated with increased body size and low insulin sensitivity. Sexually mature OF pigs had higher IGF-1 plasma concentrations than their lean littermates (P < 0.05). In the OF group, TGs and glucose were both decreased (P < 0.05). Muscle PPARgamma and alpha in OF pubescent pigs as compared to NF pigs were 11 times higher and 20 times lower, respectively (P < 0.01).


CONCLUSIONS
Obesity and insulin resistance induced by overfeeding mini-pigs during development and puberty were not associated with the cluster of metabolic modifications frequently observed in their adult littermates. Increased IGF-1 concentrations and modifications of skeletal muscle PPAR (alpha and gamma) expressions may help the young obese pig to partially regulate its glycaemia and triglyceridaemia through an increase of fat mass, which maintains its high insulin sensitivity.
Sébert
S P
SP
Unité des Fonctions Digestives et de Nutrition Humaine, Institut National de la Recherche Agronomique (INRA), Nantes, France.
Lecannu
G
G
Kozlowski
F
F
Siliart
B
B
Bard
J M
JM
Krempf
M
M
Champ
M M-J
MM
D000273:Adipose Tissue / Q000254:growth & development / Q000378:metabolism*; D000375:Aging / Q000378:metabolism; D000818:Animals; D000886:Anthropometry; D001835:Body Weight; D002648:Child; D004195:Disease Models, Animal; D018507:Gene Expression Regulation, Developmental; D006801:Humans; D007333:Insulin Resistance; D007334:Insulin-Like Growth Factor I / Q000378:metabolism / Q000502:physiology*; D008099:Liver / Q000378:metabolism; D008297:Male; D018482:Muscle, Skeletal / Q000378:metabolism; D009765:Obesity / Q000378:metabolism* / Q000503:physiopathology; D047492:Peroxisome Proliferator-Activated Receptors / Q000502:physiology*; D012741:Sexual Maturation; D013552:Swine; D013556:Swine, Miniature
D047492:Peroxisome Proliferator-Activated Receptors; D007334:Insulin-Like Growth Factor I