Robinson I C, Clark R G
Division of Neurophysiology and Neuropharmacology, National Institute for Medical Research, London, UK.
Acta Paediatr Scand Suppl. 1988;347:93-103.
According to the original somatomedin hypothesis, GH promotes growth by generating 'somatomedins' or insulin-like growth factors (IGFs) in the liver. The advent of large amounts of IGF-I produced by recombinant DNA technology has now allowed testing of this hypothesis, by comparing the growth promoting activity of IGF-I and GH in three animal models of growth deficiency. When injected or infused subcutaneously, or infused intravenously, IGF-I is a weak growth promoter in the hypophysectomized rat compared with GH, even when infused in combination with small amounts of GH. Growth arrest in the diabetic rat was corrected by insulin infusion which also restored GH secretion. Insulin or IGF-I caused a large initial weight gain in diabetic rats, accompanied by a partial correction of food and water balance, even in the presence of persistent hyperglycaemia. A new mutant GH deficient dwarf rat grows in response to both GH and IGF-I infusions, but these agents elicit different patterns of organ growth. For the same overall body growth, GH was more effective in stimulating bone growth, whereas IGF-I stimulated renal and splenic growth. This new dwarf rat may prove useful for the study of the relative growth promoting effects of IGF-I and GH in more detail in future.
根据最初的生长调节素假说，生长激素（GH）通过在肝脏中产生“生长调节素”或胰岛素样生长因子（IGF）来促进生长。现在，通过重组DNA技术大量生产的IGF-I的出现，使得通过比较IGF-I和GH在三种生长缺陷动物模型中的促生长活性来检验这一假说成为可能。当皮下注射、皮下输注或静脉输注时，与GH相比，IGF-I在垂体切除的大鼠中是一种较弱的生长促进剂，即使与少量GH联合输注时也是如此。胰岛素输注可纠正糖尿病大鼠的生长停滞，同时也恢复了GH的分泌。胰岛素或IGF-I可使糖尿病大鼠最初体重大幅增加，即使在持续高血糖的情况下，也伴有食物和水平衡的部分恢复。一种新的生长激素缺乏型侏儒大鼠对GH和IGF-I输注均有生长反应，但这些因子引发不同的器官生长模式。对于相同的总体生长，GH在刺激骨骼生长方面更有效，而IGF-I则刺激肾脏和脾脏生长。这种新的侏儒大鼠可能在未来更详细地研究IGF-I和GH的相对促生长作用方面证明是有用的。
