title: Effect of transforming growth factor-beta on insulin-like growth factor 1- and dexamethasone-induced proliferation and differentiation in primary cultures of pig preadipocytes.
abstract: The purpose of this study was to examine the effects of a known inhibitor, transforming growth factor-beta1 (TGF-beta1) versus the known stimulators insulin-like growth factor-1 (IGF-1) and dexamethasone (DEX) on pig preadipocyte differentiation in serum and serum-free primary cultures. In cultures with serum, preadipocyte and nonpreadipocyte replication was increased (p < 0.02) by IGF-1 and by TGF-beta1 (p < 0.05; p < 0.001). IGF-1 (10 nM) enhanced preadipocyte differentiation (p < 0.05) in serum-supplemented (1% pig serum) cultures, whereas TGF-beta1 (15 pM) reduced preadipocyte differentiation (p < 0.01) in the presence and absence of IGF-1. Furthermore, GPDH (SN-glycerol-3-phosphate dehydrogenase) specific activity (marker that indicates differentiation) was decreased (p < 0.05) by adding TGF-beta1 to serum-free cultures, but TGF-beta1 had little effect in serum-supplemented cultures. DEX significantly enhanced GPDH activity and fat cell cluster number, whereas pretreatment with TGF-beta1 eliminated the DEX enhancement. We have shown for the first time that TGF-beta can decrease (p < 0.01) the cellular secretion of IGF-1 by pig adipose tissue cells and counter the effects of exogenous IGF-1. These studies indicate that TGF-beta1 may not inhibit adipocyte development in the initial growth phase, but may inhibit differentiation and/or hypertrophy (lipid filling) at a later stage of development.
authors.affiliation: US Department of Agriculture, Athens, Ga., USA.
authors.forename: R L
authors.initials: RL
authors.lastname: Richardson
authors.forename: G J
authors.initials: GJ
authors.lastname: Hausman
authors.forename: H R
authors.initials: HR
authors.lastname: Gaskins
mesh_terms: D017667:Adipocytes / Q000187:drug effects* / Q000502:physiology; D000818:Animals; D000831:Animals, Newborn; D015415:Biomarkers; D002454:Cell Differentiation / Q000187:drug effects*; D002455:Cell Division / Q000187:drug effects*; D002478:Cells, Cultured; D003470:Culture Media / Q000737:chemistry; D003907:Dexamethasone / Q000494:pharmacology*; D004790:Enzyme Induction / Q000187:drug effects; D005938:Glucocorticoids / Q000494:pharmacology*; D005993:Glycerolphosphate Dehydrogenase / Q000378:metabolism; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology*; D013552:Swine; D016212:Transforming Growth Factor beta / Q000494:pharmacology*
chemical_list: D015415:Biomarkers; D003470:Culture Media; D005938:Glucocorticoids; D016212:Transforming Growth Factor beta; D007334:Insulin-Like Growth Factor I; D003907:Dexamethasone; D005993:Glycerolphosphate Dehydrogenase; C036140:L-alpha-glycerol-phosphate oxidase