Effects of recombinant ovine leptin on in vitro lipolysis and lipogenesis in subcutaneous adipose tissue from lactating and nonlactating sheep.
Direct effects of recombinant ovine leptin on adipose metabolism in sheep were investigated. Lipolytic and lipogenic rates were assessed following preincubation of subcutaneous adipose tissue explants with recombinant ovine leptin. Leptin had no consistent effect on the basal (unstimulated) lipolytic rate in adipose tissue from wethers. Lipolytic rate measured in the presence of combinations of adenosine deaminase, isoprenaline, and N6-phenylisopropyl adenosine was unaffected by pretreatment with leptin. In lactating ewes, there was no relationship between increasing concentrations of leptin and basal lipolytic rate. Leptin had no effect on basal (unstimulated) lipogenesis, or on insulin-stimulation or growth hormone inhibition of lipogenesis in adipose tissue from wethers. Lipogenesis in adipose tissue from lactating ewes was also unaffected by preincubation with leptin; however, at supraphysiological concentrations of leptin, there was a small reduction in the rate of insulin-stimulated lipogenesis. Leptin failed to induce phosphorylation of the signal transducers and activators of transcription, STAT 3 and STAT 5, in sheep adipocytes. These results suggest that leptin does not have a direct physiological effect on subcutaneous adipose tissue metabolism in sheep.
Newby
D
D
Hannah Research Institute, Ayr, United Kingdom.
Gertler
A
A
Vernon
R G
RG
D000243:Adenosine Deaminase / Q000502:physiology; D017667:Adipocytes / Q000378:metabolism / Q000502:physiology; D000273:Adipose Tissue / Q000187:drug effects* / Q000378:metabolism; D000318:Adrenergic beta-Agonists / Q000494:pharmacology; D000818:Animals; D015153:Blotting, Western / Q000662:veterinary; D046508:Culture Techniques; D004268:DNA-Binding Proteins / Q000378:metabolism; D005260:Female; D013006:Growth Hormone / Q000494:pharmacology; D007545:Isoproterenol / Q000494:pharmacology; D007774:Lactation / Q000187:drug effects / Q000378:metabolism*; D020738:Leptin / Q000378:metabolism / Q000494:pharmacology*; D008055:Lipids / Q000096:biosynthesis*; D008066:Lipolysis / Q000187:drug effects*; D008297:Male; D008894:Milk Proteins; D010660:Phenylisopropyladenosine / Q000494:pharmacology; D010766:Phosphorylation / Q000187:drug effects; D011994:Recombinant Proteins / Q000378:metabolism / Q000494:pharmacology; D050796:STAT3 Transcription Factor; D050799:STAT5 Transcription Factor; D012756:Sheep / Q000378:metabolism / Q000502:physiology*; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D015534:Trans-Activators / Q000378:metabolism
D000318:Adrenergic beta-Agonists; D004268:DNA-Binding Proteins; D020738:Leptin; D008055:Lipids; D008894:Milk Proteins; D011994:Recombinant Proteins; D050796:STAT3 Transcription Factor; D050799:STAT5 Transcription Factor; D015534:Trans-Activators; D010660:Phenylisopropyladenosine; D013006:Growth Hormone; D000243:Adenosine Deaminase; D007545:Isoproterenol