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This Article Full Text (PDF) All Versions of this Article: jas.2008-1340v1 87/14_suppl/E72    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Smith, S. B. Articles by Sawyer, J. E. Search for Related Content PubMed PubMed Citation Articles by Smith, S. B. Articles by Sawyer, J. E.

Cellular regulation of bovine intramuscular adipose tissue development and composition

S. B. Smith^*, H. Kawachi, C. B. Choi, C. W. Choi, G. Wu^* and J. E. Sawyer^*

^* Department of Animal Science,Texas A&M University, College Station 77843-2471 , Kyoto University, Kyoto, Sakyo-ku, Japan , Yeungman University, Gyeongsan, Korea National Institute of Animal Science, Suwon, Korea

sbsmith{at}tamu.edu

Abstract

It is well documented that grain feeding stimulates adipogenesis in beef cattle, whereas pasture feeding depresses the development of adipose tissues, including intramuscular (i.m.) adipose tissue. Additionally, production practices that depress adipocyte differentiation also limit the synthesis of monounsaturated fatty acids (MUFA). Marbling scores and MUFA increase in parallel, indicating that stearoyl-CoA desaturase (SCD) gene expression is closely associated with and(or) necessary for differentiation of marbling adipocytes. Similarly, marbling scores and fatty acid indices of SCD activity are depressed in response to dietary vitamin A restriction. In bovine preadipocytes, vitamins A and D both decrease glycerol-3-phosphate dehydrogenase (GPDH) activity, an index of adipocyte differentiation, whereas incubation of bovine preadipocytes with L-ascorbic acid-2-phosphate increases GPDH activity. Exposing bovine preadipocytes to zinc also stimulates adipogenesis, putatively by inhibiting nitric oxide (NO) production. However, incubation of bovine preadipocytes with arginine, a biological precursor of NO, strongly promotes differentiation in concert with increased SCD expression. This indicates that the effect of either arginine or zinc on adipogenesis is independent of NO synthesis in bovine preadipocytes. Enhanced expression of SCD is associated with a greater accumulation of MUFA both in bovine preadipocyte cultures and during development in growing steers. In bovine preadipocytes, trans-10, cis-12 conjugated linoleic acid (t10,c12 CLA) strongly depresses adipocyte differentiation and SCD gene expression, thereby reducing MUFA concentrations. The bovine preadipocyte culture studies indicate that any production practice that elevates vitamins A or D or t10,c12 CLA in bovine adipose tissue will reduce i.m. adipose tissue development. Conversely, supplementation with vitamin C or zinc may promote the development of i.m. adipose tissue.

Key Words: Adipose tissue • bovine • fatty acids • intramuscular • stearoyl coenzyme a desaturase • vitamins