Effect of dietary protein intake on renal growth: possible role of insulin-like growth factor-I.
Insulin-like growth factor-I (IGF-I) has been implicated as a possible mediator of renal hypertrophy after uninephrectomy and diabetes mellitus. Because renal hypertrophy is also a consequence of high protein intake, we studied the effect of varying concentrations of dietary protein on circulating levels and renal tissue content of IGF-I. Male Sprague-Dawley rats were fed isocaloric diets containing high (50%, HP), normal (20%, NP) or low (6%, LP) dietary protein for up to 14 days before they were killed. As expected, renal size (dry kidney weight) was greater in HP-fed rats and smaller in LP-fed rats when compared with NP-fed animals (HP, 1415 +/- 26 mg [p < 0.01 vs NP]; NP, 1148 +/- 27 mg; LP, 838 +/- 16 mg [p < 0.01 vs NP]), and most of the relative changes in kidney size occurred during the first week of ingestion of the experimental diet. Renal hypertrophy in the HP-fed animals was accompanied at day 3 by a significant rise in kidney tissue IGF-I that remained elevated at day 7 but had fallen to baseline values by day 14. The rise in renal IGF-I content in the HP-fed rat was accompanied by increases in circulating IGF-I on day 3 only. Both circulating and renal tissue IGF-I levels were suppressed in the LP-fed animals at 3, 7, and 14 days. These data confirm that varying dietary protein intake has profound effects on both circulating and renal IGF-I levels.(ABSTRACT TRUNCATED AT 250 WORDS)
Murray
B M
BM
Department of Medicine, State University of New York at Buffalo.
Campos
S P
SP
Schoenl
M
M
MacGillivray
M H
MH
D000818:Animals; D004044:Dietary Proteins / Q000008:administration & dosage*; D006984:Hypertrophy; D007334:Insulin-Like Growth Factor I / Q000502:physiology*; D007668:Kidney / Q000254:growth & development* / Q000378:metabolism / Q000473:pathology; D008297:Male; D009929:Organ Size; D051381:Rats; D017207:Rats, Sprague-Dawley
D004044:Dietary Proteins; D007334:Insulin-Like Growth Factor I