title: Early treatment of obese (ob/ob) mice with triiodothyronine increases oxidative metabolism in muscle but not in brown adipose tissue or liver.
abstract: We explored the possibility that early replacement of low triiodothyronine (T3) may improve the low oxidative metabolism in metabolically important tissues of ob/ob mice. Triiodothyronine doses (2.5 to 25.0 micrograms/100 g body wt) were injected intraperitoneally into ob/ob and non-ob/ob mice daily from 3 wk until 6 wk of age. Untreated ob/ob and non-ob/ob mice were injected with saline (pH 9.1). Food intake was equalized across all groups. At 6 wk of age, the O2 consumption of muscle, white and brown adipose tissues, and hepatocytes was measured. The saline-treated ob/ob mice showed lower muscle weights, higher fat pad and liver weights, and larger fat cell sizes than saline-treated non-ob/ob mice. In ob/ob mice, tissue O2 consumption was the same in muscle, lower in brown and white adipose tissues, but higher in liver compared with values in non-ob/ob mice. Triiodothyronine treatment in ob/ob mice resulted in lower values for body weight, liver weight, hepatocyte number, liver protein, epididymal fat pad weight, and white adipocyte number and size than in saline-treated ob/ob mice. Triiodothyronine treatment increased soleus muscle, liver and brown adipose tissue O2 consumption in non-ob/ob mice. In ob/ob mice, triiodothyronine increased only soleus muscle O2 consumption and required higher doses than in non-ob/ob mice to achieve an effect. These data are consistent with the concept of tissue triiodothyronine resistance in ob/ob mice. Low triiodothyronine levels and tissue resistance to triiodothyronine might be important early defects in this obesity syndrome.
authors: Food Science and Human Nutrition Department, Iowa State University, Ames 50011.
authors: S S
authors: SS
authors: Oh
authors: M L
authors: ML
authors: Kaplan
mesh_terms: D000273:Adipose Tissue / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D002001:Adipose Tissue, Brown / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D000704:Analysis of Variance; D000818:Animals; D001835:Body Weight; D002452:Cell Count; D002478:Cells, Cultured; D003964:Diaphragm / Q000254:growth & development; D004435:Eating; D008099:Liver / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008820:Mice, Obese; D024510:Muscle Development; D009124:Muscle Proteins / Q000187:drug effects; D018482:Muscle, Skeletal / Q000187:drug effects / Q000378:metabolism*; D009765:Obesity / Q000188:drug therapy* / Q000378:metabolism; D009929:Organ Size; D010101:Oxygen Consumption / Q000187:drug effects; D014284:Triiodothyronine / Q000494:pharmacology / Q000627:therapeutic use*
chemical_list: D009124:Muscle Proteins; D014284:Triiodothyronine