Growth Hormone Increases Mrna Levels Of Ppar5 And Foxo1 In Skeletal Muscle Of Growth Hormone Deficient Lit/lit Mice

摘要

GH plays an important role in lipid metabolism as a partitioning hormone. PPAR8 regulates lipid oxidation in skeletal muscle and is activated by several physiological ligands including fatty acids. To investigate whether GH has an effect on the regulation of transcription of PPAR8 and other genes involved in energy metabolism in skeletal muscle, mRNA levels were studied by real-time RT-PCR in lit/lit mice (isolated GH deficiency) and lit/+ mice controls (normal GH levels). Mice received either a single bolus (120 ng/g) of rat GH or vehicle, and skeletal muscle was collected 4h later. PPAR8 mRNA was increased in vehicle-treated lit/lit mice compared to vehicle-treated lit/+ mice (1.67 fold, P<0.05). lit/ lit mice treated with GH showed a further increase in PPARδ mRNA levels (2.83 fold vs. vehicle-treated lit/+ mice, P<0.001). mRNA levels of Foxol were increased in vehicle-treated lit/lit mice compared to vehicle-treated lit/+ mice (1.74 fold, P<0.05). lit/lit mice treated with GH showed a further increase in Foxol mRNA levels (6.30 fold vs. vehicle-treated lit/+ mice, P<0.001). mRNA levels of acyl CoA-oxidase showed a trend to be higher in vehicle-treated lit/lit mice compared to vehicle-treated lit/+ mice. This reached statistical significance in GH-treated lit/lit mice compared to vehicle-treated lit/+ mice (2.11 fold, P<0.05). In summary, mRNA levels of PPARδ and Foxol were increased in skeletal muscle of GH-deficient mice, and further acutely increased by GH administration. These results suggest that GH plays a relevant role in the lipid catabolism in skeletal muscle.