Regulation of insulin-like growth factor messenger ribonucleic acid in rat growth plate by growth hormone.
The mechanism of action for the stimulatory effect of GH on longitudinal bone growth is not yet clarified. Several recent reports indicate that GH has a direct effect at the site of the epiphyseal growth plate, as opposed to the somatomedin hypothesis which holds that the effect of GH is mediated by circulating insulin-like growth factors (IGFs). Using a RNA probe in a solution hybridization assay we investigated the presence of IGF-I mRNA in rat rib growth plate. Hypophysectomy resulted in a decrease in the number of IGF-I mRNA copies compared to that in normal rats. Replacement treatment with GH restored the number of transcripts in a specific and dose-dependent manner. The results show that GH regulates the level of IGF-I mRNA in rat rib growth plate and give further support to the hypothesis that locally produced IGF-I might contribute to the stimulatory effect of GH on longitudinal bone growth.
Isgaard
J
J
Department of Physiology, University of Göteborg, Sweden.
Möller
C
C
Isaksson
O G
OG
Nilsson
A
A
Mathews
L S
LS
Norstedt
G
G
D000199:Actins / Q000235:genetics; D000818:Animals; D002356:Cartilage / Q000378:metabolism; D004247:DNA / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004838:Epiphyses / Q000187:drug effects / Q000378:metabolism*; D013006:Growth Hormone / Q000494:pharmacology*; D007016:Hypophysectomy; D007334:Insulin-Like Growth Factor I / Q000235:genetics*; D008297:Male; D012333:RNA, Messenger / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D013002:Somatomedins / Q000235:genetics*
D000199:Actins; D012333:RNA, Messenger; D013002:Somatomedins; D007334:Insulin-Like Growth Factor I; D013006:Growth Hormone; D004247:DNA