Compensatory renal growth: role of growth hormone and insulin-like growth factor-I.
Recent experimental evidence suggests that insulin-like growth factor-I (IGF-I) may be involved in compensatory renal growth (CRG). This study was designed to determine the relative contribution of IGF-I and growth hormone (GH) to the CRG that takes place in rats following uninephrectomy (UNx). We also studied the respective role of GH and IGF-I in the stimulation of CRG induced by a high protein diet (HPD). CRG was studied 7 days after UNx in Wistar rats and in a new mutant strain of dwarf rats, selectively deficient in GH. Prior to UNx, rats of both strains were pre-fed (14 days) either a medium-protein diet (MPD, casein 18%) or a HPD (54%). On MPD, CRG was comparable in Wistar (17.6 +/- 3.1%, M +/- SD) and dwarf (14.4 +/- 4.8%) rats. The HPD enhanced CRG in the Wistars (27 +/- 3.9%, P less than 0.005) but not in the dwarfs (14.9 +/- 2%). CRG in both experimental groups involved renal hypertrophy and hyperplasia. Control (baseline) serum, liver and kidney IGF-I were significantly less in dwarf rats. However, following UNx, on a MPD, kidney IGF-I increased significantly in both Wistar and dwarf rats: Wistar, pre-UNx, 310 +/- 46 ng/g tissue; post-UNx, 405 +/- 54 ng/g, P less than 0.005; dwarfs, pre-UNx, 205 +/- 35 ng/g; post-UNx 426 +/- 90 ng/g, P less than 0.001. On a HPD a further significant increase in renal IGF-I was only observed in Wistar rats (505 +/- 46 ng/g). No change in serum or liver IGF-I was observed after UNx in either strain.(ABSTRACT TRUNCATED AT 250 WORDS)
el Nahas
A M
AM
Department of Renal Medicine, Northern General Hospital, Sheffield, UK.
Le Carpentier
J E
JE
Bassett
A H
AH
D000222:Adaptation, Physiological; D000818:Animals; D004044:Dietary Proteins / Q000494:pharmacology; D013006:Growth Hormone / Q000172:deficiency / Q000502:physiology*; D007334:Insulin-Like Growth Factor I / Q000502:physiology*; D007668:Kidney / Q000502:physiology*; D008297:Male; D009392:Nephrectomy / Q000379:methods; D051381:Rats; D011919:Rats, Inbred Strains; D011922:Rats, Mutant Strains; D013002:Somatomedins / Q000502:physiology*
D004044:Dietary Proteins; D013002:Somatomedins; D007334:Insulin-Like Growth Factor I; D013006:Growth Hormone