Dual regulation of insulin-like growth factor I expression during renal hypertrophy.
We examined the regulation of insulin-like growth factor I (IGF-I) in kidney during the renal hypertrophy produced by two different experimental models: growth hormone treatment of hypophysectomized rats and compensatory hypertrophy subsequent to unilateral nephrectomy. Immunostaining for IGF-I in collecting ducts was enhanced in kidneys from growth hormone-repleted hypophysectomized rats, and the levels of IGF-I mRNAs were increased. In compensatory hypertrophy, no enhancement of the intensity of immunostaining was observed in kidneys of nephrectomized rats until 5 days postnephrectomy, at which time immunostainable IGF-I was increased markedly in medullary collecting ducts of hypertrophied kidneys compared with kidneys from sham-operated animals. No difference in steady-state levels of any IGF-I mRNA species was detected in whole kidneys or in collecting ducts from nephrectomized or sham-operated rats at any time postnephrectomy. Our findings demonstrate an increase in both IGF-I mRNA and in immunostainable IGF-I in collecting duct in the setting of growth hormone-induced renal hypertrophy but suggest that other, possibly translational, mechanisms underlie the induction of IGF-I synthesis during compensatory hypertrophy.
Lajara
R
R
Department of Internal Medicine, Washington University School of Medicine, St. Louis, Missouri 63110.
Rotwein
P
P
Bortz
J D
JD
Hansen
V A
VA
Sadow
J L
JL
Betts
C R
CR
Rogers
S A
SA
Hammerman
M R
MR
D000818:Animals; D002462:Cell Membrane / Q000378:metabolism; D013006:Growth Hormone / Q000494:pharmacology; D006984:Hypertrophy; D007016:Hypophysectomy; D007334:Insulin-Like Growth Factor I / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism; D007335:Insulin-Like Growth Factor II / Q000378:metabolism; D007668:Kidney / Q000187:drug effects / Q000378:metabolism / Q000473:pathology*; D007679:Kidney Medulla / Q000378:metabolism; D007685:Kidney Tubules, Collecting / Q000378:metabolism; D008297:Male; D009399:Nephrons / Q000378:metabolism; D012333:RNA, Messenger / Q000187:drug effects / Q000235:genetics; D051381:Rats; D011919:Rats, Inbred Strains; D011956:Receptors, Cell Surface / Q000378:metabolism; D017451:Receptors, Somatomedin; D012016:Reference Values; D013002:Somatomedins / Q000096:biosynthesis*; D014158:Transcription, Genetic / Q000187:drug effects
D012333:RNA, Messenger; D011956:Receptors, Cell Surface; D017451:Receptors, Somatomedin; D013002:Somatomedins; D007334:Insulin-Like Growth Factor I; D007335:Insulin-Like Growth Factor II; D013006:Growth Hormone