Clenbuterol increases muscle fiber size and GATA-2 protein in rat skeletal muscle in utero

Diane Downie, Margaret I. Delday, Charlotte A. Maltin, Alan A. Sneddon

Research output: Contribution to journalArticle

8 Citations (Scopus)

Abstract

Certain beta 2-adrenoceptor agonists, such as clenbuterol, are known to elicit a muscle-specific anabolism or hypertrophy in both normal and catabolic muscle in a wide variety of species. However, the underlying mechanism(s) of the beta 2-agonist-induced anabolism remains unclear. This study aimed to determine the effects of clenbuterol administration in utero on skeletal muscle and to examine the underlying molecular mechanisms. Pregnant rats were fed clenbuterol (2 mg/kg diet) from Day 4 of gestation (4 dg) until weanling and fetal samples were taken from 13.5, 15.5, 17.5, and 19.5 dg and from 1d neonatal pups. Muscles were analyzed for total DNA, RNA and protein and sections examined morphologically for changes in muscle development. Western and immunohistochemical analyses were performed to identify changes in known myogenic signaling proteins, Clenbuterol increased the size of both fast and slow fibers in utero which was associated with a decreased DNA:protein ratio (28%) and an increased RNA:DNA ratio (36%). Additionally, drug treatment in utero induced a decrease in the fast:slow fiber ratio (38%). These myogenic changes were correlated with an increase in the GATA-2 hypertrophic transcription factor at both 17.5 dg (by 250%) and 19.5 dg (by 40%) in fetuses from clenbuterol treated dams. In addition, drug treatment resulted in increased membrane association of PKC-mu at 17.5 dg (325%) and increased PKC-alpha cytosolic abundance (40%) and PKC-theta membrane abundance at 19.5 dg (250%). These results are the first demonstration that beta 2-agonists such as clenbuterol may act through upregulating the GATA-2 transcription factor and implicate certain PKC isoforms in the drug-induced regulation of skeletal muscle development. Mol. Reprod. Dev. 75: 785-794, 2008. (C) 2007 Wiley-Liss, lnc.

Original languageEnglish
Pages (from-to)785-794
Number of pages10
JournalMolecular Reproduction and Development
Volume75
Issue number5
Early online date18 Oct 2007
DOIs
Publication statusPublished - May 2008

Keywords

  • beta-adrenergic agonist
  • hypertrophy
  • anabolism
  • fetal
  • kinase-C
  • agonist clenbuterol
  • gene-expression
  • PKC-theta
  • growth
  • beta
  • differentiation
  • stimulation
  • atrophy
  • ß-adrenergic agonist

Cite this

Clenbuterol increases muscle fiber size and GATA-2 protein in rat skeletal muscle in utero. / Downie, Diane; Delday, Margaret I.; Maltin, Charlotte A.; Sneddon, Alan A.

In: Molecular Reproduction and Development, Vol. 75, No. 5, 05.2008, p. 785-794.

Research output: Contribution to journalArticle

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AB - Certain beta 2-adrenoceptor agonists, such as clenbuterol, are known to elicit a muscle-specific anabolism or hypertrophy in both normal and catabolic muscle in a wide variety of species. However, the underlying mechanism(s) of the beta 2-agonist-induced anabolism remains unclear. This study aimed to determine the effects of clenbuterol administration in utero on skeletal muscle and to examine the underlying molecular mechanisms. Pregnant rats were fed clenbuterol (2 mg/kg diet) from Day 4 of gestation (4 dg) until weanling and fetal samples were taken from 13.5, 15.5, 17.5, and 19.5 dg and from 1d neonatal pups. Muscles were analyzed for total DNA, RNA and protein and sections examined morphologically for changes in muscle development. Western and immunohistochemical analyses were performed to identify changes in known myogenic signaling proteins, Clenbuterol increased the size of both fast and slow fibers in utero which was associated with a decreased DNA:protein ratio (28%) and an increased RNA:DNA ratio (36%). Additionally, drug treatment in utero induced a decrease in the fast:slow fiber ratio (38%). These myogenic changes were correlated with an increase in the GATA-2 hypertrophic transcription factor at both 17.5 dg (by 250%) and 19.5 dg (by 40%) in fetuses from clenbuterol treated dams. In addition, drug treatment resulted in increased membrane association of PKC-mu at 17.5 dg (325%) and increased PKC-alpha cytosolic abundance (40%) and PKC-theta membrane abundance at 19.5 dg (250%). These results are the first demonstration that beta 2-agonists such as clenbuterol may act through upregulating the GATA-2 transcription factor and implicate certain PKC isoforms in the drug-induced regulation of skeletal muscle development. Mol. Reprod. Dev. 75: 785-794, 2008. (C) 2007 Wiley-Liss, lnc.

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