title: Melengestrol acetate alters muscle cell proliferation in heifers and steers.
abstract: In vitro experiments were performed to investigate the effects of melengestrol acetate (MGA) or progesterone (P4) on bovine muscle satellite cells and C2C12 myoblasts. Addition of MGA at physiological and supraphysiological concentrations resulted in a dose-dependent decrease (P < 0.05) in DNA synthesis as measured by [3H]-thymidine incorporation (TI). Similarly, P4 addition (0.01 nM) reduced (P < 0.05) TI. Addition of MGA (10 nM) increased (P < 0.05) IGF-I mRNA abundance but did not affect myogenin mRNA. Progesterone addition (10 nM) increased myogenin mRNA abundance (P < 0.05). In C2C12 cultures, P4 addition resulted in a dose-dependent decrease in TI. The antiprogestin RU486, in combination with MGA or P4, also resulted in reduced (P < 0.05) TI. Treatment with RU486 alone had a negative effect (P < 0.05) on TI that was similar to the progestins. Treatment of C2C12 myoblasts with MGA (100 nM) resulted in an increase (P < 0.05) in myogenin mRNA. These studies suggest that progestins may reduce satellite cell proliferation, ultimately affecting carcass composition.
authors.affiliation: Department of Animal Sciences and Industry, Kansas State University, Manhattan 66506, USA.
authors.forename: E K
authors.initials: EK
authors.lastname: Sissom
authors.forename: C D
authors.initials: CD
authors.lastname: Reinhardt
authors.forename: B J
authors.initials: BJ
authors.lastname: Johnson
mesh_terms: D000818:Animals; D002417:Cattle / Q000378:metabolism*; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D005260:Female; D007334:Insulin-Like Growth Factor I / Q000378:metabolism; D008297:Male; D008552:Melengestrol Acetate / Q000494:pharmacology*; D015735:Mifepristone / Q000494:pharmacology; D018482:Muscle, Skeletal / Q000166:cytology* / Q000187:drug effects*; D018008:Myogenin / Q000378:metabolism; D011374:Progesterone / Q000494:pharmacology; D012333:RNA, Messenger / Q000378:metabolism; D032496:Satellite Cells, Skeletal Muscle / Q000166:cytology / Q000187:drug effects / Q000378:metabolism
chemical_list: D018008:Myogenin; D012333:RNA, Messenger; D015735:Mifepristone; D011374:Progesterone; D008552:Melengestrol Acetate; D007334:Insulin-Like Growth Factor I