Histomorphometric Study of the Enhancement of Renal Compensatory Hypertrophy by ACTH in the Rat

Summary

In the female adult rat, renal compensatory hypertrophy is greatly enhanced by hyperadrenocorticism elicited by the administration of ACTH given at a dose of 18 Y/100 g BW/d for 7 days after uninephrectomy (UN). This renotrophic effect of ACTH is particularly prominent in rats drinking a NaCl solution (9 g/l). In the present experiments, we performed histomorphometrical measurements of the glomerular tuft (GT) and the proximal tubule (PT) in the hypertrophying kidney (HK) remaining 7 days after UN in 10 rats treated with ACTH and 7 control animals. The histologic preparations were examined under light microscropy with the “Kontron” image analyzer. ACTH increased the weight of the HK (1213.8 ± 20.3 mg versus 1037.3 ± 13.3, p < 0.001) and determined an enlargement of the cross sectional area of the GT (12559 ± 3351.3 μ² versus 10486 ± 407.5, p < 0.01) and of the epithelial area of the PT (1751 ± 40.8 μ² versus 1586 ± 41.5, p < 0.025). These morphometrical data are consistent with the increased Protein/DNA ratio - a marker of cellular hypertrophy - found in other rats studied under the same experimental conditions. The increased weight gain of the HK elicited by ACTH is related to the hypertrophy of the epithelial cells of the PT and possibly to an enlargement of the glomeruli.

Key-Words:

Renal Compensatory Hypertrophy - ACTH - Hyperadrenocorticism - Histomorphometry - Glomerular Tuft - Proximal Tubule