TY - JOUR
T1 - Triiodothyronine differentially regulates key metabolic factors in lean and obese cats
AU - Hoenig, M.
AU - Caffall, Z.
AU - Ferguson, D. C.
N1 - Funding Information:
This study has been supported in part by a grant from the Veterinary Medical Experimental Station, University of Georgia, Athens, GA.
PY - 2008/4
Y1 - 2008/4
N2 - The effect of a 2-week administration of 75 μg triiodothyronine (T3) on substrate oxidation, heat production, non-esterified fatty acids, and leptin was evaluated in eight lean (three females and five males) and eight obese (five females and three males) age-matched adult neutered cats. In addition, using real-time RT-PCR, expression of muscle and adipose tissue uncoupling proteins (UCP2 and UCP3), deiodinase 1 and 2 (D1; D2), and peroxisome proliferator-activated receptor (PPAR) α and γ and peroxisome-proliferator-activator receptor-gamma co-activator 1α (PGC1) was examined. Compared to lean cats, obese cats had increased NEFA, leptin, UCP2, and D1mRNA in muscle and UCP3mRNA levels in fat, but lower heat production, and fat PPARs and PGC1. T3 administration increased thermogenesis and NEFA in lean and obese cats, and adipose tissue PPARγ in lean cats. It also increased muscle D1 in lean and D2 in obese cats. The increase in muscle D2 was interpreted to be reflective of the reduced serum total T4 concentration following T3 suppression of the pituitary. No effect was seen on leptin, or UCP2 and 3. This shows that T3 regulates thermogenesis but not through changes in uncoupling protein expression. It also indicates that PPARs have an important role in the pathogenesis of obesity in cats.
AB - The effect of a 2-week administration of 75 μg triiodothyronine (T3) on substrate oxidation, heat production, non-esterified fatty acids, and leptin was evaluated in eight lean (three females and five males) and eight obese (five females and three males) age-matched adult neutered cats. In addition, using real-time RT-PCR, expression of muscle and adipose tissue uncoupling proteins (UCP2 and UCP3), deiodinase 1 and 2 (D1; D2), and peroxisome proliferator-activated receptor (PPAR) α and γ and peroxisome-proliferator-activator receptor-gamma co-activator 1α (PGC1) was examined. Compared to lean cats, obese cats had increased NEFA, leptin, UCP2, and D1mRNA in muscle and UCP3mRNA levels in fat, but lower heat production, and fat PPARs and PGC1. T3 administration increased thermogenesis and NEFA in lean and obese cats, and adipose tissue PPARγ in lean cats. It also increased muscle D1 in lean and D2 in obese cats. The increase in muscle D2 was interpreted to be reflective of the reduced serum total T4 concentration following T3 suppression of the pituitary. No effect was seen on leptin, or UCP2 and 3. This shows that T3 regulates thermogenesis but not through changes in uncoupling protein expression. It also indicates that PPARs have an important role in the pathogenesis of obesity in cats.
KW - Deiodinase
KW - Leptin
KW - Obesity
KW - PPAR
KW - UCP
UR - http://www.scopus.com/inward/record.url?scp=40249091431&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=40249091431&partnerID=8YFLogxK
U2 - 10.1016/j.domaniend.2007.06.002
DO - 10.1016/j.domaniend.2007.06.002
M3 - Article
C2 - 17683895
AN - SCOPUS:40249091431
SN - 0739-7240
VL - 34
SP - 229
EP - 237
JO - Domestic Animal Endocrinology
JF - Domestic Animal Endocrinology
IS - 3
ER -