Compensatory Renal Hypertrophy in the Absence of Androgen Binding1 RONALD A. MALT,2 SUSUMU OHNO, AND JEAN K. PADDOCK Surgical Services, Massachusetts General Hospital and Shriners Burns Institute, Department of Surgery, Harvard Medical School, Boston, Massachusetts 02114, and Department of Biology, City of Hope Hospital, Duarte, California 91010 groups (33-43%). The magnitude of the increase and the contents of protein, RNA, and DNA were the same in the Tfm/Y mice and the female mice. Androgens are not essential to compensatory renal hypertrophy, but they promote larger mice with larger kidneys. (Endocrinology 96: 806, 1975)
ABSTRACT. As a direct test for a role of androgens, compensatory renal hypertrophy was studied in normal male mice, in androgen-insensitive T/m/Y mice, and in sibling normal female mice. Fifteen days after unilateral nephrectomy, although the kidneys of the normal male mice were larger, relative increases in renal weight were similar in all
I R E C T effects of androgens on t h e rodent
D
tween
kidney are uncertain. Experiments are hindered by artifacts difficult to control, as, for example, hormone-induced changes in diet and precursor pools of amino acids and nucleotides. Correlations have usually been drawn from doses of hormones injected rather than from serum and tissue levels (1,2). The possibility of differences between mice and rats has sometimes not been explicitly made. Thus, administration of androgens is said to increase the weight of mouse kidneys and the incorporation of amino acid (3-7); to the contrary, exogenous testosterone does not modify relative increments in weight during compensatory hypertrophy of the rat kidney (8). To circumvent some of the problems, we studied compensatory renal hypertrophy in mice with testicular feminization. Through a single mutation these animals lack the ability to bind testosterone to organs that are normally androgen responsive (9-11). Their target organs fail to respond even to large doses of androgens.
9:00 AM and
11:00 AM under
light
ether
anesthesia and with care to preserve the adrenal (12). Supplied with standard laboratory pellets and water, groups of 5 mice of a single strain were caged together under alternating 12-h cycles of light and dark. They were killed by cervical dislocation on the 15 postoperative day. Protein content was estimated by the method of Lowry et al. (13) and nucleic acid contents by the method of Scott et al. (14) modified by Hinrichs et al. (15).
Results
Normal males were about 28-29% heavier than the other mice at the beginning and end of the experiment; their kidneys weighed 45-52% more (Table 1). The protein content of these kidneys (15.6 mg/g ± 0.2 mg SEM) was slightly lower than the 16.6 ± 0.4 mg protein/g for Tfm/Y mice (P = 0.05) and the 17.3 ± 0.3 mg protein/g for the females (P < 0.001), but not enough to account for appreciable differences in total weight as a result of different cellular composition. Despite the differences in absolute weight, the relative weights of all 3 groups of kidney Materials and Methods increased 33-43% as a result of contralateral nephrectomy (Table 1). The ratio of the RNA Three groups of mice were used: normal males ( + + +/Y6), males genetically identical except for the content to the DNA content is an estimate of testicular feminization locus (Tfm + +/Y$), and normal amount of RNA in an average renal cell (16-18). sibling females with tabby coat (+Tab+/Y9). Left As a consequence of a greater concentration of nephrectomy was performed through the flank be- RNA in the kidneys of the male mice, but equal concentrations of DNA in kidneys of all 3 groups, RNA/DNA in kidneys of the male mice Received July 15, 1974. 1 This work was supported by NIH Grants AM- was about 20% greater than that in the other groups (Table 2), probably reflecting larger 12769 and NCI NO1CB33907. 2 cells. RNA/DNA was the same in the other two Address reprint requests to R. A. Malt, M.D., groups. Data similar to those shown in Tables 1 Massachusetts General Hospital, Boston, Masand 2 were obtained in a pilot experiment. sachusetts 02114. 806
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807
N O T E S AND C O M M E N T S TABLE 1. Effect of unilateral nephrectomy after 15 days (mean ± SE) Body weight (g)
+Tab+/+ + + 9 r/m + +/Y9*
Kidney weight (mg)
Before
After
Before
After
Kidney weight % Increase
28.1 ± 0.8* 21.2 ± 0.5 22.3 ± 0.5
29.8 ± 0.8* f 22.4 ± 0.6 24.2 ± 0.7
201 ± 6* 132 ± 7 133 ± 4
267 ± 10*§ 188 ± 8§ 181 ± 5§
33 43 36
* Means compared with means of two other groups of mice, P < 0.001 (Student's t test), t Postoperative mean compared with preoperative mean, P = 0.05. § Postoperative mean compared with preoperative mean, P < 0.001. Ten mice were used in each group. TABLE 2. Nucleic acid concentrations 15 days after unilateral nephrectomy (mean ± SE)
H+/Y(» +Tab+/+ + + o r/m + +/Y 9*
tig RNA/nig kidney
g DNA/mg kidney
/ig RNA/jug DNA
5.00 ± 0.08* 4.34 + 0.12 3.99 ± 0.15
3.43 ± 0.06 3.67 + 0.06 3.54 + 0.12
1.47 ± 0.03* 1.18 + 0.03 1.13 ± 0.03
* Means compared with means of two other groups of mice, P
ABSTRACT. As a direct test for a role of androgens, compensatory renal hypertrophy was studied in normal male mice, in androgen-insensitive T/m/Y mice, and in sibling normal female mice. Fifteen days after unilateral nephrectomy, although the kidneys of the normal male mice were larger, relative increases in renal weight were similar in all
I R E C T effects of androgens on t h e rodent
D
tween
kidney are uncertain. Experiments are hindered by artifacts difficult to control, as, for example, hormone-induced changes in diet and precursor pools of amino acids and nucleotides. Correlations have usually been drawn from doses of hormones injected rather than from serum and tissue levels (1,2). The possibility of differences between mice and rats has sometimes not been explicitly made. Thus, administration of androgens is said to increase the weight of mouse kidneys and the incorporation of amino acid (3-7); to the contrary, exogenous testosterone does not modify relative increments in weight during compensatory hypertrophy of the rat kidney (8). To circumvent some of the problems, we studied compensatory renal hypertrophy in mice with testicular feminization. Through a single mutation these animals lack the ability to bind testosterone to organs that are normally androgen responsive (9-11). Their target organs fail to respond even to large doses of androgens.
9:00 AM and
11:00 AM under
light
ether
anesthesia and with care to preserve the adrenal (12). Supplied with standard laboratory pellets and water, groups of 5 mice of a single strain were caged together under alternating 12-h cycles of light and dark. They were killed by cervical dislocation on the 15 postoperative day. Protein content was estimated by the method of Lowry et al. (13) and nucleic acid contents by the method of Scott et al. (14) modified by Hinrichs et al. (15).
Results
Normal males were about 28-29% heavier than the other mice at the beginning and end of the experiment; their kidneys weighed 45-52% more (Table 1). The protein content of these kidneys (15.6 mg/g ± 0.2 mg SEM) was slightly lower than the 16.6 ± 0.4 mg protein/g for Tfm/Y mice (P = 0.05) and the 17.3 ± 0.3 mg protein/g for the females (P < 0.001), but not enough to account for appreciable differences in total weight as a result of different cellular composition. Despite the differences in absolute weight, the relative weights of all 3 groups of kidney Materials and Methods increased 33-43% as a result of contralateral nephrectomy (Table 1). The ratio of the RNA Three groups of mice were used: normal males ( + + +/Y6), males genetically identical except for the content to the DNA content is an estimate of testicular feminization locus (Tfm + +/Y$), and normal amount of RNA in an average renal cell (16-18). sibling females with tabby coat (+Tab+/Y9). Left As a consequence of a greater concentration of nephrectomy was performed through the flank be- RNA in the kidneys of the male mice, but equal concentrations of DNA in kidneys of all 3 groups, RNA/DNA in kidneys of the male mice Received July 15, 1974. 1 This work was supported by NIH Grants AM- was about 20% greater than that in the other groups (Table 2), probably reflecting larger 12769 and NCI NO1CB33907. 2 cells. RNA/DNA was the same in the other two Address reprint requests to R. A. Malt, M.D., groups. Data similar to those shown in Tables 1 Massachusetts General Hospital, Boston, Masand 2 were obtained in a pilot experiment. sachusetts 02114. 806
The Endocrine Society. Downloaded from press.endocrine.org by [${individualUser.displayName}] on 13 November 2015. at 17:19 For personal use only. No other uses without permission. . All rights reserved.
807
N O T E S AND C O M M E N T S TABLE 1. Effect of unilateral nephrectomy after 15 days (mean ± SE) Body weight (g)
+Tab+/+ + + 9 r/m + +/Y9*
Kidney weight (mg)
Before
After
Before
After
Kidney weight % Increase
28.1 ± 0.8* 21.2 ± 0.5 22.3 ± 0.5
29.8 ± 0.8* f 22.4 ± 0.6 24.2 ± 0.7
201 ± 6* 132 ± 7 133 ± 4
267 ± 10*§ 188 ± 8§ 181 ± 5§
33 43 36
* Means compared with means of two other groups of mice, P < 0.001 (Student's t test), t Postoperative mean compared with preoperative mean, P = 0.05. § Postoperative mean compared with preoperative mean, P < 0.001. Ten mice were used in each group. TABLE 2. Nucleic acid concentrations 15 days after unilateral nephrectomy (mean ± SE)
H+/Y(» +Tab+/+ + + o r/m + +/Y 9*
tig RNA/nig kidney
g DNA/mg kidney
/ig RNA/jug DNA
5.00 ± 0.08* 4.34 + 0.12 3.99 ± 0.15
3.43 ± 0.06 3.67 + 0.06 3.54 + 0.12
1.47 ± 0.03* 1.18 + 0.03 1.13 ± 0.03
* Means compared with means of two other groups of mice, P
