title: The interrelationship between and the regulation of hepatic growth hormone receptors and circulating GH binding protein in the pig.
abstract: We evaluated the interrelationship between, and regulation of, the hepatic growth hormone receptor and serum GH binding protein (GH BP) in pigs treated with recombinant porcine growth hormone (rpGH). Infant and pubertal male pigs (N = 5 per group) received either rpGH 0.15 mg/kg daily or diluent intramuscularly for 12 days. Somatic growth, serum IGF-I and GH BP and [125I]bovine GH (bGH) binding to MgCl2-treated hepatic membrane homogenates were examined. Marked age-related increases were seen in serum GH BP (p less than 0.001) and [125I]bGH binding to hepatic membranes (p less than 0.001). GH BP was increased in rpGH treated animals (p = 0.03), from 13.8 +/- 1.2 (mean +/- 1 x SEM) (controls) to 17.8 +/- 2.0% in infants, and from 35.2 +/- 2.6 (controls) to 41.8 +/- 3.4% in pubertal animals. [125I]bGH binding to hepatic membranes was also increased by rpGH treatment (p less than 0.05), from 7.0 +/- 1.6 (controls) to 15.4 +/- 3.6% in infants and from 53.7 +/- 7.1 (controls) to 65.1 +/- 11.8% in pubertal animals. No significant interaction between age and treatment was seen. Overall, serum GH BP correlated significantly with [125I]bGH membrane capacity (r = 0.82, p less than 0.001), with a correlation of r = 0.83 in the infant animals but no significant correlation in the pubertal animals considered alone (r = 0.13). Serum IGF-I correlated significantly with serum GH BP (r = 0.93, p less than 0.001) and [125I]bGH membrane binding capacity (r = 0.91, p less than 0.001). These observations suggest that serum GH BP levels reflect major changes of hepatic GH receptor status.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Department of Paediatrics, University of Auckland, New Zealand.
authors.forename: G R
authors.initials: GR
authors.lastname: Ambler
authors.forename: B H
authors.initials: BH
authors.lastname: Breier
authors.forename: A
authors.initials: A
authors.lastname: Surus
authors.forename: H T
authors.initials: HT
authors.lastname: Blair
authors.forename: S N
authors.initials: SN
authors.lastname: McCutcheon
authors.forename: A
authors.initials: A
authors.lastname: Silbergeld
authors.forename: P D
authors.initials: PD
authors.lastname: Gluckman
mesh_terms: D000375:Aging / Q000378:metabolism*; D000818:Animals; D000831:Animals, Newborn; D002352:Carrier Proteins / Q000097:blood*; D002462:Cell Membrane / Q000378:metabolism; D013006:Growth Hormone / Q000494:pharmacology; D007334:Insulin-Like Growth Factor I / Q000378:metabolism; D008099:Liver / Q000378:metabolism*; D008297:Male; D011986:Receptors, Somatotropin / Q000378:metabolism*; D011994:Recombinant Proteins / Q000494:pharmacology; D012741:Sexual Maturation; D013552:Swine; D015430:Weight Gain
chemical_list: D002352:Carrier Proteins; D011986:Receptors, Somatotropin; D011994:Recombinant Proteins; D007334:Insulin-Like Growth Factor I; D013006:Growth Hormone; C051815:somatotropin-binding protein