Hypopituitary dwarf mice were found to have reduced levels of serum somatomedin-like activity compared with normal mice of the Snell strain. Treatment with bovine growth hormone for 3 and 7 days resulted in growth without significantly increased levels of serum somatomedin-like activity, as detected by in-vitro uptake of 35SO4(2-) into normal rat cartilage; only after treatment for 14 days was somatomedin activity significantly raised. However, treatment for 2 days with bovine growth hormone, bovine prolactin or thyroxine resulted in a dose-dependent increase in in-vivo uptake of 35SO4(2-) into dwarf mouse costal cartilage; growth hormone and thyroxine did not act synergistically. Ten days of treatment with growth hormone promoted a dose-dependent increase in both growth (increased weight gain and tail length) and in-vivo of 35SO4(2-). Increase in tail length was correlated with uptake of 35S04(2-). Thus, in-vivo uptake of 35SO4(2-) into dwarf mouse costal cartilage provides a sensitive method for detecting a dose-related effect of growth hormone.
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Holder et al. (1980) studied this question.