Small stature and insulin-like growth factors: prolonged treatment of mini-poodles with recombinant human insulin-like growth factor I.
The short stature of mini-poodles is associated with low serum levels of IGF-I. Standard poodles are taller and have considerably higher serum levels of IGF-I. Low IGF-I serum levels may be a symptom or the cause of small stature. We, therefore, undertook a study in which serum IGF-I levels of mini-poodles were elevated over a prolonged period of time by a constant infusion of rhIGF-I and the growth rate of the mini-poodles was followed. We infused four mini-poodles from day 91 to day 221 of age with 6 mg/day of recombinant human insulin-like growth factor I (rhIGF-I). Serum levels of IGF-I rose from about 160 to about 500 micrograms/l. Blood glucose remained within normal limits. Stimulation tests with clonidine and with GHRH revealed suppression of endogenous GH secretion during the IGF-I infusion. Serum levels of IGF-II and of creatinine were lower in the IGF-I-infused animals. Radial length and body weight did not increase to a greater extent in the IGF-I infused dogs than in controls. However, 'adapted body mass index' (aBMI = gram body weight/(mm radial length)2) decreased in each of the IGF-I infused animals, whereas it increased in each of the control dogs (p less than 0.05). We conclude that long-term infusion of IGF-I does not stimulate growth in young mini-poodles, but may change body composition.
Guler
H P
HP
Department of Medicine, University Hospital, Zürich, Switzerland.
Binz
K
K
Eigenmann
E
E
Jäggi
S
S
Zimmermann
D
D
Zapf
J
J
Froesch
E R
ER
D000818:Animals; D001786:Blood Glucose / Q000032:analysis; D004285:Dogs; D006128:Growth / Q000187:drug effects*; D013006:Growth Hormone / Q000378:metabolism; D013007:Growth Hormone-Releasing Hormone / Q000494:pharmacology; D007279:Injections, Subcutaneous; D007334:Insulin-Like Growth Factor I / Q000008:administration & dosage* / Q000032:analysis; D007335:Insulin-Like Growth Factor II / Q000032:analysis; D008297:Male; D011863:Radioimmunoassay; D011869:Radioligand Assay; D013002:Somatomedins / Q000008:administration & dosage*; D013997:Time Factors
D001786:Blood Glucose; D013002:Somatomedins; D007334:Insulin-Like Growth Factor I; D007335:Insulin-Like Growth Factor II; D013006:Growth Hormone; D013007:Growth Hormone-Releasing Hormone