Recent studies have revealed that IGF-I produced in kidney are of two fractions; GH dependent and GH nondependent IGF-I. The role of GH nondependent IGF-I is interesting in renal hypertrophy and glomerulosclerosis because GH is clearly related
with
hypertrophy accompanying glomerulosclerosis is not sen in GH deficient animal. The relationship of the high protein diet and the IGF-I production under the deprivation of GH was studied. In hypophysectomized Sprague-Dawley rat, the level of serum
IGF-I
was measured using radioimmunoassay, and renal IGF-I production evaluated by immunohistochemistry druing both normal and high protein diet. Serum IGF-I of rats on high protein diet was significantly higher than that fed normal protein diet. After
unilateral nephrectomy, the level of serum IGF-I was significantly increased in both normal and high protein diet groups. Henle's loop, distal convoluted tubale and collecting duct were weakly stained with normal protein diet. With high protein
diet,
the staining intensities increased at these portion, and distal part of proximal convoluted tubule and stratight tubule were weakly stained. After unilateral nephrectomy, distal convoluted tubule and collecting duct were densely stained with
normal
protein diet. With high protein diet, the staining intensities increased in distal part of proximal convoluted tubule and Henle's loop. Regardless of the types of protein diet, the specific difference between unilateral nephrectomized rats and
shamoperated rats was immunoreactivity of the distal convoluted tubule. In conclusion, it is suggested that GH non-dependent IGF-I is mainly produced in distal convoluted tubule during compensatory renal hypertrophy, and protein diet mainly
affect
IGF-I
production of distal part of proximal convoluted tubule and Henle's loop.
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