Regulation of lipoprotein lipase activity and mRNA content in rat epididymal adipose tissue in vitro by recombinant tumour necrosis factor.
Tumour necrosis factor (TNF) has previously been shown to decrease lipoprotein lipase (LPL) activity and mRNA levels in 3T3-L1 cells and in adipose tissue from rats and guinea pigs when injected in vivo, but not to alter LPL activity in human adipocytes incubated in vitro. The effect of recombinant human TNF on LPL activity and mRNA levels in rat epididymal adipose tissue incubated in vitro was examined. LPL activity and mRNA levels fell in adipose tissue taken from fed rats and incubated in Krebs-Henseleit bicarbonate medium with glucose. The addition of insulin and dexamethasone prevented these falls. TNF (400 ng/ml) produced a fall of approx. 50% in LPL activity after 2 h of incubation and of approx. 30% in LPL mRNA levels after 3 h. TNF did not decrease LPL activity in isolated adipocytes. These results demonstrate that rat adipose tissue incubated in vitro is responsive to TNF whereas isolated adipocytes are not.
Department of Biochemistry and Genetics, University of Newcastle upon Tyne, U.K.
A G
AG
Mackay
J D
JD
Oliver
M P
MP
Rogers
D000273:Adipose Tissue / Q000187:drug effects / Q000201:enzymology*; D000818:Animals; D003907:Dexamethasone / Q000494:pharmacology; D007328:Insulin / Q000494:pharmacology; D007700:Kinetics; D008071:Lipoprotein Lipase / Q000235:genetics / Q000378:metabolism*; D008297:Male; D012333:RNA, Messenger / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D011994:Recombinant Proteins / Q000494:pharmacology; D014404:Tubulin / Q000235:genetics; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*
D007328:Insulin; D012333:RNA, Messenger; D011994:Recombinant Proteins; D014404:Tubulin; D014409:Tumor Necrosis Factor-alpha; D003907:Dexamethasone; D008071:Lipoprotein Lipase