GLP-2 and GIP exert separate effects on bone turnover: A randomized, placebo-controlled, crossover study in healthy young men

Bone. 2019 Aug:125:178-185. doi: 10.1016/j.bone.2019.05.014. Epub 2019 May 15.

Abstract

Background: Glucagon-like peptide-2 (GLP-2) and glucose-dependent insulinotropic polypeptide (GIP) both inhibit bone resorption in humans but the underlying mechanisms are poorly understood. In vitro, GLP-2 activates the GIP-receptor (GIPR).

Objective: Based on in vitro studies, we hypothesized that the antiresorptive effect of GLP-2 was mediated through the GIPR. This was tested using the selective GIPR-antagonist GIP(3-30)NH2.

Methods: The study was a randomized, single-blinded, placebo-controlled, crossover study conducted at Hvidovre University Hospital, Denmark. Eight healthy young men were included and studied on four study days: GIP (200 μg), GLP-2 (800 μg), GIP(3-30)NH2 (800 pmol/kg/min) + GLP-2 (800 μg), and placebo. The main outcomes were bone resorption measured as collagen type 1 C-terminal telopeptide (CTX) and bone formation measured as procollagen type 1 N-terminal propeptide (P1NP).

Results: CTX (mean ± SEM) significantly decreased after both GIP (to 55.3 ± 6.3% of baseline at t = 90 min) and GLP-2 (to 60.5 ± 5.0% of baseline at t = 180 min). The maximal reduction in CTX after GIP(3-30)NH2 + GLP-2 (to 63.2 ± 3.1% of baseline) did not differ from GLP-2 alone (p = 0.95) nor did net AUC0-240 (-6801 ± 879%*min vs -6027 ± 648%*min, p = 0.56). At t = 30 min, GIP significantly (p < 0.0001) increased P1NP to 115.1 ± 2.2% of baseline compared with 103.1 ± 1.5% after placebo. Both GLP-2 and GIP(3-30)NH2 + GLP-2 significantly (p < 0.0001) decreased P1NP to 91.3 ± 1.1% and 88.1 ± 3.0% of baseline, respectively (at t = 45 min) compared with placebo.

Conclusions: GIPR antagonism did not inhibit the GLP-2-induced reduction in bone resorption (CTX) in healthy young men. In contrast to GLP-2, GIP increased P1NP despite decreasing CTX indicating an uncoupling of bone resorption from formation. Thus, GLP-2 and GIP seem to exert separate effects on bone turnover in humans.

Clinical trials information: ClinicalTrials.gov (NCT03159741).

Keywords: Bone formation; Bone resorption; CTX; P1NP; PTH.

Publication types

  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Animals
  • Blood Glucose / drug effects
  • Bone Remodeling / drug effects*
  • COS Cells
  • Chlorocebus aethiops
  • Cross-Over Studies
  • Cyclic AMP / metabolism
  • Gastric Inhibitory Polypeptide / pharmacology*
  • Glucagon-Like Peptide 2 / pharmacology*
  • Humans
  • Male
  • Receptors, Gastrointestinal Hormone / metabolism
  • Young Adult

Substances

  • Blood Glucose
  • Glucagon-Like Peptide 2
  • Receptors, Gastrointestinal Hormone
  • Gastric Inhibitory Polypeptide
  • gastric inhibitory polypeptide receptor
  • Cyclic AMP

Associated data

  • ClinicalTrials.gov/NCT03159741