Rat insulin-like growth factor-I and -II mRNAs are unchanged during compensatory adrenal growth but decrease during ACTH-induced adrenal growth.
The insulin-like growth factors (IGFs) may be important autocrine and paracrine mediators of organ growth. We used solution-hybridization/ribonuclease protection assays to examine IGF-I and IGF-II mRNA abundance during hypertrophy or the rat adrenal gland induced by unilateral adrenalectomy or by adrenocorticotropic hormone (ACTH) infusion. Adrenal IGF-I mRNA did not change during the period of rapid organ growth at 18 or 66 h after unilateral adrenalectomy. ACTH infusion induced a time- and dose-dependent decrease in adrenal IGF-I mRNA despite significant increases in gland size. IGF-II mRNA also remained unchanged after unilateral adrenalectomy and decreased after ACTH infusion, to a greater extent than IGF-I mRNA. Liver IGF-I mRNA did not change with ACTH exposure, indicating an effect specific to the adrenal. We also measured adrenal P450scc mRNA as a marker of steroidogenic capacity. P450scc mRNA was unchanged after unilateral adrenalectomy and increased with ACTH infusion. Thus IGF-I and IGF-II mRNAs respond in parallel, but in different fashions with different stimuli for adrenal growth. The decrease in IGF mRNA after exposure to ACTH may be a factor in the ACTH-induced inhibition of compensatory hypertrophy after unilateral adrenalectomy.
Townsend
S F
SF
Department of Pediatrics, University of California, San Francisco 94143.
Dallman
M F
MF
Miller
W L
WL
D000311:Adrenal Glands / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D000315:Adrenalectomy; D000818:Animals; D016375:Antisense Elements (Genetics); D002455:Cell Division; D003345:Corticosterone / Q000494:pharmacology; D003366:Cosyntropin / Q000494:pharmacology*; D007334:Insulin-Like Growth Factor I / Q000235:genetics*; D007335:Insulin-Like Growth Factor II / Q000235:genetics*; D007700:Kinetics; D008099:Liver / Q000187:drug effects / Q000378:metabolism; D008297:Male; D015347:RNA Probes; D012333:RNA, Messenger / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D012016:Reference Values
D016375:Antisense Elements (Genetics); D015347:RNA Probes; D012333:RNA, Messenger; D003366:Cosyntropin; D007334:Insulin-Like Growth Factor I; D007335:Insulin-Like Growth Factor II; D003345:Corticosterone