Insulin-like growth factor I stimulates growth in normal growing rats.
The scarcity of purified somatomedin/insulin-like growth factor (SM/IGF) has prevented investigation of the mechanisms of SM/IGF action. Recently insulin-like growth factor I (IGF-I) has been synthesized by recombinant DNA technology. The availability of large quantities of the biosynthetic IGF-I made it possible to study its effects by administering 120 micrograms/day via s.c. implanted minipump to rats for 7 days. After this 7 day administration of IGF-I, the body weight increased to 197.6 +/- 3.5% of initial values; the value was significantly greater than that of the control (179.4 +/- 3.7% of initial values, P less than 0.01). The body length and tibial epiphyseal width in IGF-I-treated rats were also significantly increased over those of control rats. The weights of kidneys, liver, testes and pituitary in IGF-I-treated rats were greater than those in control rats as well. These results provide a first demonstration that IGF-I stimulates growth in normal rats in vivo, and suggest that IGF-I might be useful in the treatment of growth retardation.
D000818:Animals; D001835:Body Weight / Q000187:drug effects; D006128:Growth / Q000187:drug effects*; D006132:Growth Plate / Q000187:drug effects; D007334:Insulin-Like Growth Factor I / Q000097:blood / Q000494:pharmacology*; D008297:Male; D009929:Organ Size / Q000187:drug effects; D051381:Rats; D011919:Rats, Inbred Strains; D013002:Somatomedins / Q000494:pharmacology*
D013002:Somatomedins; D007334:Insulin-Like Growth Factor I