Effect of age and protein restriction on the clearance and secretion of growth hormone in the domestic fowl.
Metabolic clearance rates (MCR) and secretion rates for growth hormone (GH) were determined in young (6-wk-old) chicks and adults (1 yr old) as well as in chicks fed low protein diets for 2 wk. Birds were either conscious or anesthetized during these determinations in the latter study. Age-related differences in plasma concentrations of GH reflect greater secretion of GH in younger chicks (3.5-fold increase). The MCR was reduced by 35% in chicks compared with adults, but when expressed per unit metabolic body weight, was higher in the young chickens. The MCR in protein-restricted chicks was 28% lower than in that of controls. However, when the MCR was calculated on a metabolic body weight basis, protein-restricted and control chicks did not differ in MCR. Elevated plasma concentrations of GH in unanesthetized, protein-restricted chicks were due to greater GH secretion (2.4-fold) of these chicks compared with secretions of chicks fed control diets. Basal secretions of GH, determined in the anesthetized chicks, did not differ between dietary treatments. These results indicate that secretion of GH but not clearance was affected by protein restriction in conscious birds.
Lauterio
T J
TJ
Department of Internal Medicine, Eastern Virginia Medical School, Norfolk.
Scanes
C G
CG
D000367:Age Factors; D000818:Animals; D002645:Chickens / Q000378:metabolism*; D004044:Dietary Proteins / Q000494:pharmacology*; D013006:Growth Hormone / Q000097:blood / Q000378:metabolism* / Q000493:pharmacokinetics; D008297:Male; D008657:Metabolic Clearance Rate / Q000187:drug effects
D004044:Dietary Proteins; D013006:Growth Hormone