In vivo modulation by glucose of human placental growth hormone level in the maternal circulation

Abstract

The growth hormone (GH)-enhancing monoclonal antibody (MAb) OA15 defines a functionally linear epitope (residues 91–102) lying on the loop connecting helices 2 and 3 of the bovine GH (bGH) molecule. Further studies revealed that a number of analogue peptides were possible by substituting residues within the epitope peptide. The aim of this study was examine the ability of antisera prepared against these peptides to mimic the ability of MAb OA15 to enhance bGH and porcine GH (pGH) activity. Antisera against the epitope peptide and its analogues were characterised by their ability to bind to bGH by solid-phase ELISA and liquid phase RIA. Antisera binding [125I]-bGH enhanced the somatogenic activity of both exogenous bGH and pGH as determined by the incorporation of 35SO42− into the costal cartilage of Snell dwarf mice. Long term treatment of Snell dwarf mice with GH complexed to anti-peptide F (QFLSRITNSLV) antisera stimulated mice to reach their normal mature weight significantly faster than that of mice treated with GH alone, although the final weight of the animal was not altered. This finding suggests that enhancement takes place via normal physiological processes and that antibody-mediated enhancement of GH action may have a potential application in manipulating growth in the livestock industry.