Insulin inhibits lipolytic activity and degradation of beta-lipotropin in rabbit adipose tissue.
beta-Lipotropin, a pituitary peptide, is a potent stimulator of lipolysis in rabbit adipose tissue in vitro and in vivo. Insulin inhibited the beta-lipotropin (1-100 nM)-stimulated glycerol release from rabbit adipocytes and fat pads significantly at concentrations of 10 and 100 microM. Both these concentrations of insulin also decreased the degradation of beta-lipotropin in intact adipose tissue to the same extent as the lipolytic activity. Furthermore, insulin reduced the degradation of beta-lipotropin in rabbit adipose tissue homogenate. Like insulin, several lysosomotropic agents also decreased significantly the degradation and the lipolytic activity of beta-lipotropin. On the other hand, insulin-like growth factor I in lower concentrations (1-100 nM) did not effect degradation and lipolytic activity of beta-lipotropin in rabbit adipose tissue. Thus, a direct influence of insulin on lysosomal enzymes degrading beta-lipotropin in rabbit adipose tissue can be suggested.
Richter
W O
WO
Department of Medicine II, University of Munich, F.R.G.
Jacob
B G
BG
Schwandt
P
P
D000273:Adipose Tissue / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D000818:Animals; D005260:Female; D005990:Glycerol / Q000378:metabolism; D066298:In Vitro Techniques; D007328:Insulin / Q000494:pharmacology*; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology; D008066:Lipolysis / Q000187:drug effects*; D011817:Rabbits; D013268:Stimulation, Chemical; D008083:beta-Lipotropin / Q000378:metabolism / Q000494:pharmacology*
D007328:Insulin; D007334:Insulin-Like Growth Factor I; D008083:beta-Lipotropin; D005990:Glycerol