Monoclonal antibodies to growth hormone (GH) prolong liver GH binding and GH-induced IGF-I/IGFBP-3 synthesis.
(1999) American journal of physiology — Vol. 277, n° 2 Pt 1, p. E308-E315 (1999)
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- This time-course study further explored the mechanisms whereby monoclonal antibodies (MAbs) may enhance growth hormone (GH) effects. Hypophysectomized rats were killed 0, 1, 3, 6, 12, 24, and 48 h after a single injection of bovine (b) GH alone or complexed with an anti-bGH MAb. Serum insulin-like growth factor I (IGF-I) concentrations were increased more and for a longer period after MAb-GH complexes (peak at 24 h: 295 +/- 24 ng/ml) than after bGH alone (peak at 12 h: 219 +/- 37 ng/ml; P < 0.01), whereas liver IGF-I mRNA was similar at 12 h in both groups but remained higher at 24 h (by 65%, P < 0.001) and 48 h (by 64%, P < 0.001) in the presence of the MAb. Induction of serum insulin-like growth factor-binding protein (IGFBP)-3 and liver IGFBP-3 mRNA by bGH also was markedly amplified by the MAb (3.6- and 2-fold at 24 h, respectively; P < 0.01). GH receptors (GHR) remained occupied for a longer period after MAb-GH injection (36 +/- 16 and 35 +/- 8% at 6 and 12 h, respectively) compared with bGH alone (0 +/- 28 and -15 +/- 11%), whereas total liver GH-binding sites and GHR mRNA levels were not affected by the MAb. We conclude that MAbs against GH amplify and prolong the serum IGF-I response to GH, which may result from both a prolongation of liver IGF-I synthesis and an enhanced induction of IGFBP-3. These two effects may in turn be the consequences of sustained GH binding to its liver receptors in the presence of MAb.
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Beauloye, V., Muaku, S. M., Lause, P., Portetelle, D., Renaville, R., Robert, A., Ketelslegers, J.-M., & Maiter, D. (1999). Monoclonal antibodies to growth hormone (GH) prolong liver GH binding and GH-induced IGF-I/IGFBP-3 synthesis. American journal of physiology, 277(2 Pt 1), E308-E315. https://doi.org/10.1152/ajpendo.1999.277.2.E308 (Original work published 1999)