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Research Paper|Volume 7, Issue 4|pp 241—255

Thyroxine modifies the effects of growth hormone in Ames dwarf mice

Andrew Do1, Vinal Menon1,2, Xu Zhi1,3, Adam Gesing4, Denise S. Wiesenborn1,5,6, Adam Spong7, Liou Sun7, Andrzej Bartke7, Michal M. Masternak1,8
  • 1Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, FL 32827, USA
  • 2Department of Cell Biology and Anatomy, School of Medicine, University of South Carolina Columbia, SC 29209, USA
  • 3Center of Reproductive Medicine, Department of Obstetrics and Gynecology, Peking University Third Hospital, Beijing 100191, China
  • 4Department of Oncological Endocrinology, Medical University of Lodz, 90‐752 Lodz, Poland
  • 5Department of Medical Biochemistry and Molecular Biology, University of Saarland, 66421 Homburg, Germany
  • 6Department of Biotechnology, University of Applied Sciences Kaiserslautern, 66482 Zweibrücken, Germany
  • 7Department of Internal Medicine, Southern Illinois University School of Medicine, Springfield, IL 62794, USA
  • 8Department of Head and Neck Surgery, The Greater Poland Cancer Centre, 61‐866 Poznan, Poland
Received: February 15, 2015Accepted: April 16, 2015Published: April 22, 2015
https://doi.org/10.18632/aging.100739

Copyright: © 2015 Do et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Abstract

Ames dwarf (df/df) mice lack growth hormone (GH), thyroid stimulating hormone and prolactin. Treatment of juvenile df/df mice with GH alone stimulates somatic growth, reduces insulin sensitivity and shortens lifespan. Early‐life treatment with thyroxine (T4) alone produces modest growth stimulation but does not affect longevity. In this study, we examined the effects of treatment of juvenile Ames dwarf mice with a combination of GH + T4 and compared them to the effects of GH alone. Treatment of female and male dwarfs with GH + T4 between the ages of 2 and 8 weeks rescued somatic growth yet did not reduce lifespan to match normal controls, thus contrasting with the previously reported effects of GH alone. While the male dwarf GH + T4 treatment group had no significant effect on lifespan, the female dwarfs undergoing treatment showed a decrease in maximal longevity. Expression of genes related to GH and insulin signaling in the skeletal muscle and white adipose tissue (WAT) of female dwarfs was differentially affected by treatment with GH + T4 vs. GH alone. Differences in the effects of GH + T4 vs. GH alone on insulin target tissues may contribute to the differential effects of these treatments on longevity.