Serum and renal IGF-I levels after uninephrectomy in the rat

Abstract

The hypertrophy of the remaining kidney following uninephrectomy (UNx) has been related to an increase in renal insulin growth factor-I (IGF-I) content. However, while the increase in renal IGF-I lasts for only days after UNx, renal hypertrophy continues for months. In the present study we investigated whether IGF-I also plays a role in the late post uninephrectomy growth of the remaining kidney. Renal IGF-I in the remnant kidney was greater than that of control kidneys (78.3 +/- 17.3 vs 56.0 +/- 14.0 pmol g-1; p < 0.05) 3 days after UNx, tended to remain higher 30 days after UNx (83.8 +/- 23.6 vs 57.3 +/- 14.5 pmol g-1; p = 0.07), but was similar to that of the control kidney when examined 60 days after UNx (66.6 +/- 15.6 vs. 70.4 +/- 6.7 pmol g-1). Serum IGF-I in uninephrectomized rats was similar to that of controls 3 days after UNx, started to increase above the control level at day 10 after UNx and remained higher 30 and 60 days after UNx (75.9 +/- 6.9 vs. 48.7 +/- 7.3 nmol l-1 at 30 days, and 81.2 +/- 13.7 vs 52.9 +/- 11.0 nmol l-1 at day 60, p < 0.05 for both). The kidney weight of uninephrectomized rats was higher by 21% than that of controls 3 days after UNx, by 45% 30 days after UNx and by 63% 60 days after UNx (p < 0.05 for all three observations). At the end of the study, the glomerular volume of uninephrectomized rats was higher by 36% than that of the controls (p < 0.05) We suggest that in the rat, while the initial post uninephrectomy hypertrophy of the remnant kidney is associated with and most probably mediated by an increase in renal IGF-I, the hypertrophy that persists in later post UNx periods is associated with and may be mediated by an increase in serum IGF-I.

Unilateral nephrectomy diminishes ischemic acute kidney injury through enhanced perfusion and reduced pro-inflammatory and pro-fibrotic responses

“…Proliferation of tubular epithelial cells is crucial for renal recovery following IRI [ 15 ]. UNx stimulates a wide range of growth factors such as IGF-1 [ 16 , 17 ], GH [ 18 , 19 ], HGF [ 20 ], VEGF [ 21 ] and EGF [ 22 , 23 ] with beneficial pleiotropic effects (e.g. proliferative, anti-apoptotic and tubulogenic as well as vasodilatory properties) [ 24 – 26 ].…”

Establishment of Metanephros Transplantation in Mice Highlights Contributions by Both Nephrectomy and Pregnancy to Developmental Progression

“…3). A number of experiments have shown that compensatory hypertrophy and hyperfunction of nephrons occurs in the remaining kidney of animals who have undergone UNX due to the induction of a number of growth factors such as insulin-like growth factor [20] and hepatocyte growth factor [21,22,23]. A similar mechanism may be responsible for the enhanced development of transplanted metanephroi in UNX and pregnant recipients.…”

“…This may result from upregulated factor(s) in the circulation of the pregnant recipient facilitating angiogenesis and/or organogenesis. A number of growth factors, including IGF-I, IGF-II and HGF, are highly upregulated during pregnancy [24, 25], and HGF and IGFs participate in post-UNX renal hypertrophy [20, 23]. Pregnancy has long been cited as an aggravating factor for tumorigenesis, a process dependent upon enhanced angiogenesis [26], suggesting circulating angiogenic factors may indeed contribute to the improved success of transplants in pregnant recipients.…”