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Title: SOMATOTROPIN INCREASES PROTEIN BALANCE BY LOWERING BODY PROTEIN DEGRADATIONIN FED GROWING PIGS

Author
item VANN, RHONDA - USDA/ARS CHILDREN'S NUTR
item DAVIS, TERESA - USDA/ARS CHILDREN'S NUTR
item NGUYEN, HANH - USDA/ARS CHILDREN'S NUTR
item BURRIN, DOUGLAS - USDA/ARS CHILDREN'S NUTR
item REEDS, PETER - USDA/ARS CHILDREN'S NUTR
item FIOROTTO, MARTA - USDA/ARS CHILDREN'S NUTR
item HAYMOND, MOREY - USDA/ARS CHILDREN'S NUTR
item JAHOOR, FAROOK - USDA/ARS CHILDREN'S NUTR
item Steele, Norman
item DEAVER, DANIEL - PENN STATE/DEPT ANMI SCI

Submitted to: American Journal of Physiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/1/1999
Publication Date: N/A
Citation: N/A

Interpretive Summary: Administration of recombinant somatotropin increases protein growth of muscle and visceral tissues. Protein growth, or accretion, represents the differential between protein synthesis and protein degradation. In well-fed growing pigs administered porcine somatotropin, protein growth was due to a reduction of protein degradation and a reduction of amino acid oxidation. These effects were examined by stable isotopic methodologies. High rates of protein synthesis typify growth of young animals and somatotropin did not influence this parameter. Results of this study may be of value to reduce the loss of lean body mass attributable to disease processes.

Technical Abstract: Somatotropin (ST) administration enhances protein deposition in well-nourished, growing animals. To determine whether the anbolic effect is due to an increase in protein synthesis or a decrease in proteolysis, pair-fed, weight-matched (15 kg) growing swine were treated with porcine (p) ST (150ug/kg/d, n=6) or diluent (n=6) for 7 d. Fed rates of whole-body nonoxidative leucine disposal (NOLD), whole-body leucine appearance (Ra), fractional tissue protein synthesis (Ks), urea production and leucine oxidation were determined with primed, continuous of 13C- leucine, 13C-bicarbonate, and 15N2-urea. PST administration increased (P<0.05) the weight gain to feed intake ratio, plasma insulin-like growth factor I (100%) and insulin concentrations (125%) and decreased plasma urea nitogen concentrations (53%). PST-treated animals had lower leucine Ra (-33%), leucine oxidation (-63%) and urea production (-70%). PST treatment did not alter NOLD or Ks in the longissimus dorsi, semitendinosus, or gastrocnemius muscles liver or gut. The results suggest that the mechanism by which pST treatment increases protein deposition in the continuously fed state in growing swine is through a suppression of protein degradation and amino acid catabolism rather than a stimulation of protein synthesis during meal absorption.