Effects of growth hormone on the ontogenetic allometry of craniofacial bones

Authors

  • Paula N. Gonzalez,

    1. Departmentof Cell Biology and Anatomy, University of Calgary, 3280 Hospital Drive NW, Calgary, Alberta, Canada T2N 4Z6
    2. McCaig Institute for Bone and Joint Health, Calgary, Alberta, Canada
    3. Alberta Children's Hospital Research Institute for Child and Maternal Health, Calgary, Alberta, Canada
    4. Instituto de Genética Veterinaria, IGEVET-CONICET, La Plata, Argentina
    Search for more papers by this author
  • Erika Kristensen,

    1. McCaig Institute for Bone and Joint Health, Calgary, Alberta, Canada
    2. Schulich School of Engineering, University of Calgary, Calgary, Alberta, Canada
    Search for more papers by this author
  • Douglas W. Morck,

    1. Departments of Biological Sciences and Comparative Biology and Experimental Medicine, Calgary, Alberta, Canada
    Search for more papers by this author
  • Steven Boyd,

    1. McCaig Institute for Bone and Joint Health, Calgary, Alberta, Canada
    2. Schulich School of Engineering, University of Calgary, Calgary, Alberta, Canada
    Search for more papers by this author
  • Benedikt Hallgrímsson

    Corresponding author
    1. McCaig Institute for Bone and Joint Health, Calgary, Alberta, Canada
    2. Alberta Children's Hospital Research Institute for Child and Maternal Health, Calgary, Alberta, Canada
    • Departmentof Cell Biology and Anatomy, University of Calgary, 3280 Hospital Drive NW, Calgary, Alberta, Canada T2N 4Z6
    Search for more papers by this author

Author for correspondence (e-mail: bhallgri@ucalgary.ca)

SUMMARY

Organism size is controlled by interactions between genetic and environmental factors mediated by hormones with systemic and local effects. As changes in size are usually not isometric, a considerable diversity in shape can be generated through modifications in the patterns of ontogenetic allometry. In this study we evaluated the role of timing and dose of growth hormone (GH) release on growth and correlated shape changes in craniofacial bones. Using a longitudinal study design, we analyzed GH deficient mice treated with GH supplementation commencing pre- and post-puberty. We obtained 3D in vivo micro-CT images of the skull between 21 and 60 days of age and used geometric morphometrics to analyze size and shape changes among control and GH deficient treated and non-treated mice. The variable levels of circulating GH altered the size and shape of the adult skull, and influenced the cranial base, vault, and face differently. While cranial base synchondroses and facial sutures were susceptible to either the direct or indirect effect of GH supplementation, its effect was negligible on the vault. Such different responses support the role of intrinsic growth trajectories of skeletal components in controlling the modifications induced by systemic factors. Contrary to the expected, the timing of GH treatment did not have an effect on catch-up growth. GH levels also altered the ontogenetic trajectories by inducing changes in their location and extension in the shape space, indicating that differences arose before 21 days and were further accentuated by a truncation of the ontogenetic trajectories in GHD groups.

Ancillary