Effect of growth hormone dosing on ultimate weight and length of XO mice

Mice with the karyotype 39, XO and XX mice with the same genetic background were injected for a six month period with daily subcutaneous doses of 0.5 IU biosynthetic human growth hormone (hGH) or with placebo. The XO mice dosed with hGH obtained a significantly higher body weight and greater final length than the XO mice dosed with placebo (39.2 g versus 29.0 g and 21.1 cm versus 19.2 cm respectively). The body weight remained constant after cessation of dosing. The XX mice became significantly longer but not heavier as a result of hGH dosing. The placebo dosed XO mice became significantly longer than the placebo XX mice but their body weights were comparable. Dosing with hGH caused a significant increase in growth rate in both XO and XX mice, and the ultimate body weight was reached within a significantly shorter time period. In the XO mice the hGH injections increased significantly the length and thickness of the femoral bones and the length of the tibia bones. Stimulated endogenous plasma growth hormone levels were significantly higher in XX mice compared to XO mice. Plasma IGF-I levels were significantly higher in XO compared to XX mice, but the levels were not affected by hGH dosing. XO mice may be useful in future metabolic and hormonal studies.