HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) 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 HighWire Citing Articles via Google Scholar Google Scholar Articles by White, M. E. Articles by Dayton, W. R. Search for Related Content PubMed PubMed Citation Articles by White, M. E. Articles by Dayton, W. R.

Growth factor messenger RNA levels in muscle and liver of steroid-implanted and nonimplanted steers^1,2

M. E. White, B. J. Johnson, M. R. Hathaway^* and W. R. Dayton^*,3

^* Animal Growth and Development Laboratory, Department of Animal Science, University of Minnesota, St. Paul 55108 and and Department of Animal Sciences and Industry, Kansas State University, Manhattan 66506

³ Correspondence:
348 ABLMS, 1334 Eckles Ave. (phone: 612-624-2234; fax: 612-624-3677; E-mail:
wdayton{at}umn.edu).

Ribonuclease protection assays were used to measure steady-state semimembranosus muscle and/or hepatic levels of IGF-I, IGFBP-3, IGFBP-5, hepatocyte growth factor (HGF), and myostatin messenger RNA (mRNA) in steers implanted from 32 to 38 d with Revalor-S, a combined trenbolone acetate and estradiol implant. Insulin-like growth factor-I mRNA levels were 69% higher (P < 0.01, n = 7) in the livers of implanted steers than in the livers of nonimplanted steers. Similarly, IGF-I mRNA levels were 50% higher (P < 0.05, n = 7) in the semimembranosus muscles of implanted steers than in the same muscles from nonimplanted steers. Hepatic IGFBP-3 mRNA levels were 24% higher (P < 0.07, n = 7) in implanted steers than in nonimplanted steers. Hepatic HGF and IGFBP-5 mRNA levels did not differ between implanted and nonimplanted steers. Similarly, muscle IGFBP-3, IGFBP-5, HGF, and myostatin mRNA levels were not affected by treatment. Previous data from these same steers have shown that circulating IGF-I and IGFBP-3 concentrations were 30 to 40% higher (P < 0.01, n = 7) in implanted steers than in nonimplanted, control steers. Additionally, the number of actively proliferating satellite cells that could be isolated from the semimembranosus muscle was 45% higher (P < 0.01, n = 7) for implanted steers than for nonimplanted steers. Viewed together, these data suggest that increased muscle IGF-I levels stimulate increased satellite cell proliferation, resulting in the increased muscle growth observed in Revalor-S implanted steers.

Key Words: Estradiol • Growth Promoters • Insulin-Like Growth Factor • Muscles • Steers • Trenbolone

This article has been cited by other articles:

				W. R. Dayton and M. E. White Cellular and molecular regulation of muscle growth and development in meat animals J Anim Sci, April 1, 2008; 86(14_suppl): E217 - E225. [Abstract] [Full Text] [PDF]

				K. Y. Chung and B. J. Johnson Application of cellular mechanisms to growth and development of food producing animals J Anim Sci, April 1, 2008; 86(14_suppl): E226 - E235. [Abstract] [Full Text] [PDF]

				J. M. Gonzalez, J. N. Carter, D. D. Johnson, S. E. Ouellette, and S. E. Johnson Effect of ractopamine-hydrochloride and trenbolone acetate on longissimus muscle fiber area, diameter, and satellite cell numbers in cull beef cows J Anim Sci, August 1, 2007; 85(8): 1893 - 1901. [Abstract] [Full Text] [PDF]

				E. K. Sissom, C. D. Reinhardt, and B. J. Johnson Melengestrol acetate alters muscle cell proliferation in heifers and steers J Anim Sci, November 1, 2006; 84(11): 2950 - 2958. [Abstract] [Full Text] [PDF]

				W. T. Oliver, J. Rosenberger, R. Lopez, A. Gomez, K. K. Cummings, and M. L. Fiorotto The Local Expression and Abundance of Insulin-Like Growth Factor (IGF) Binding Proteins in Skeletal Muscle Are Regulated by Age and Gender But Not Local IGF-I in Vivo Endocrinology, December 1, 2005; 146(12): 5455 - 5462. [Abstract] [Full Text] [PDF]

				R. G. Mateescu and M. L. Thonney Effect of testosterone on insulin-like growth factor-I, androgen receptor, and myostatin gene expression in splenius and semitendinosus muscles in sheep J Anim Sci, April 1, 2005; 83(4): 803 - 809. [Abstract] [Full Text] [PDF]

				J. D. Dunn, B. J. Johnson, J. P. Kayser, A. T. Waylan, E. K. Sissom, and J. S. Drouillard Effects of flax supplementation and a combined trenbolone acetate and estradiol implant on circulating insulin-like growth factor-I and muscle insulin-like growth factor-I messenger RNA levels in beef cattle J Anim Sci, December 1, 2003; 81(12): 3028 - 3034. [Abstract] [Full Text] [PDF]

				M. S. Pampusch, B. J. Johnson, M. E. White, M. R. Hathaway, J. D. Dunn, A. T. Waylan, and W. R. Dayton Time course of changes in growth factor mRNA levels in muscle of steroid-implanted and nonimplanted steers J Anim Sci, November 1, 2003; 81(11): 2733 - 2740. [Abstract] [Full Text] [PDF]

				M. E. Davis, S. L. Boyles, S. J. Moeller, and R. C. M. Simmen Genetic parameter estimates for serum insulin-like growth factor-I concentration and ultrasound measurements of backfat thickness and longissimus muscle area in Angus beef cattle J Anim Sci, September 1, 2003; 81(9): 2164 - 2170. [Abstract] [Full Text] [PDF]