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Endocrinology Vol. 139, No. 2 546-550
Copyright © 1998 by The Endocrine Society

ARTICLES

Orchiectomy Markedly Reduces the Concentration of the Three Isoforms of Transforming Growth Factor ß in Rat Bone, and Reduction Is Prevented by Testosterone1

Rajbir K. Gill, Russell T. Turner, Thomas J. Wronski2 and Norman H. Bell

Departments of Medicine and Pharmacology (R.K.G., N.H.B.), Medical University of South Carolina and Department of Veterans Affairs Medical Center, Charleston, South Carolina 29401-5799; Department of Orthopaedics (R.T.T.), Mayo Clinic, Rochester, Minnesota 55905; and Department of Physiologic Sciences (T.J.W.), University of Florida College of Veterinary Medicine, Gainesville, Florida 32610

Address all correspondence and requests for reprints to: Norman H. Bell, M.D., Veterans Affairs Medical Center, 109 Bee Street, Charleston, South Carolina 29401-5799.


   Abstract
Top
 Abstract
Introduction
 Materials and Methods
 Results
 Discussion
 References
 
Available evidence indicates that transforming growth factor ß (TGFß) is produced by bone cells, that production is enhanced by testosterone and dihydrotestosterone, and that TGFß is an important modulator of bone formation, induction, and repair. To determine the relative concentrations of isoforms of skeletal TGFß, whether orchiectomy alters the concentration of TGFß in long bones, and whether alteration is prevented by testosterone replacement, male Sprague-Dawley rats were either sham-operated and given placebo (n = 20) or orchiectomized and given either placebo (n = 20) or 100 mg testosterone (n = 20) by slow-release pellets implanted sc at the back of the neck and killed at 6 weeks. Orchiectomy did not change serum calcium and lowered serum testosterone and serum phosphorus; these reductions were prevented by testosterone replacement. TGFß1 in skeletal extracts was much more abundant than TGFß2 or TGFß3. Orchiectomy reduced skeletal TGFß by over 80 percent, and reduction was prevented by testosterone replacement. The relative abundance of the three isoforms of TGFß in bone was not influenced by orchiectomy or testosterone replacement, and skeletal messenger RNA of TGFß1 and TGFß2 was not altered 4 weeks after orchiectomy. Messenger RNA for TGFß3 was below the limits of detection. Thus, testosterone deficiency markedly diminishes skeletal TGFß, and reduction is prevented by testosterone replacement. The findings support the hypothesis that testosterone and TGFß are required for maintenance of the skeleton in male rats.


   Introduction
Top
 Abstract
 Introduction
Materials and Methods
 Results
 Discussion
 References
 
ORCHIECTOMY results in increased skeletal remodeling and loss of cancellous bone of the tibia in both young and old rats, and the loss is prevented by replacement with testosterone or dihydrotestosterone (1, 2, 3). The molecular mechanism for bone loss caused by testosterone deficiency is not established.

Previous studies support a role for transforming growth factor ß (TGFß) in bone formation, induction, and repair. Administration of TGFß over frontal or parietal bones or over femur in newborn rodents stimulates bone formation and growth at the site of administration (4, 5, 6). TGFß is localized to fracture sites during healing, regulates cell proliferation and phenotype gene expression in the fracture callus in vitro, and initiates chondrogenesis and osteogenesis in vivo (6, 7, 8). In rats, ectopic osteoinductive activity is increased by TGFß (9). Further, reductions in osteoinductive activity and TGFß are found in extracts of bones from vitamin D-deficient (10, 11) and estrogen-deficient rats (12, 13). Finally, TGFß is produced by osteoblasts and osteoblast-like cells, and synthesis is enhanced by testosterone and dihydrotestosterone (14, 15).

In view of these findings, studies were carried out to determine whether orchiectomy reduces the concentration of TGFß in long bones of rats, whether reduction can be prevented by testosterone replacement, and the relative skeletal concentration of isoforms of TGFß.


   Materials and Methods
Top
 Abstract
 Introduction
 Materials and Methods
Results
 Discussion
 References
 
Animals
For studies of bone TGFß proteins, male Sprague-Dawley rats of the same age (Holtzman, Madison, WI), weighing between 195 and 255 g, were used. Animals were randomized by weight into 3 groups of 20 rats each and were either sham-operated and given placebo or orchiectomized and given either placebo or 100 mg testosterone by sc implantation of 60-day slow-release pellets (Innovative Research of America, Sarasota, FL) at the back of the neck 1 week after surgery. In keeping with our previous studies, we elected not to include sham-operated animals given testosterone (2). Animals were fed a semisynthetic diet containing 0.6% calcium, 0.6% phosphorus, and 4 IU vitamin D3 per g of diet, as previously described (13). Six weeks after surgery, animals were anesthetized and killed by exsanguination with cardiac puncture. Serum samples and long bones were obtained for analyses.

For studies of bone messenger RNA (mRNA), male Sprague-Dawley rats of the same age, weighing between 200 and 225 g, were used. Animals were randomized into two groups of eight rats each, anesthetized, and either sham-operated or orchiectomized. Four weeks after surgery, animals were anesthetized and killed by cardiac exsanguination. Long bones were immediately obtained, cleaned, frozen in liquid N2, and stored at -80 C before analysis.

All procedures involving the animals were approved by an institutional Animal Research Committee.

Preparation of bone extracts for TGFß analysis
Bone fragments were pulverized, and bone powder was stored at -80 C and extracted by the method of Ogawa and Seyedin (16). Extracts were concentrated by dialyzing against deionized water at 4 C, lyophilized, and dissolved in PBS for assay.

Bioassay of isoforms of TGFß
The bioassay was carried out with mink lung epithelial cells (Mv l Lu CCL64) by colorimetric measurement of acid phosphatase that is proportional to cell number (16). Cells were plated at 0.5–1.0 x 106 in 100-mm culture plates and grown in DMEM supplemented with 50 U/ml penicillin, 50 µg/ml streptomycin, nonessential amino acids, L-glutamine, and 10% FCS stripped of steroids (Gemini Bioproducts, Inc., Calabasas, CA) until near confluency. Cells were detached with trypsin, collected by centrifugation at 800 x g for 2 min, and suspended in culture medium at 20,000 cells/ml. Cells were plated in 96-well microtiter plates at 1,000 cells/well (50 µl/well) and allowed to attach for 30 min. Standards of TGFß2 in the incubation medium were added in the concentration range 0.5–100 pg/well. Aliquots of samples at 2 dilutions were added to the plates. Standards and samples, in replicates of 8 each, were incubated under 5% C02, 95% air for 4 days. Wells were rinsed with PBS, filled with 100 µl 0.1 M sodium acetate (pH 5.5), 0.1 percent Triton X-100, and 100 mM p-nitro-phenyl phosphate. Plates were incubated at 37 C for 2 h, 10 µl 1.0 N NaOH was added to produce color, and (after 20 min) absorbance at 405 nm was determined with a microtiter plate reader. The dose-response curve was linear between 1 and 10 pg per well when TGFß2 was used as the standard, and all samples were within this range.

Isoforms of TGFß in skeletal extracts from control, orchiectomized animals given placebo, and orchiectomized animals given testosterone replacement were identified by use of specific neutralizing antibodies to TGFß1, TGFß2, and TGFß3 (R & D Systems, Minneapolis, MN).

RNA extraction
Total cellular RNA from cortical and cancellous bone compartments from frozen long bones were obtained by methods previously described (17). The cells were lysed with 10 ml guanidine hydrochloride, and total cellular RNA was extracted (17).

Northern blot analysis
Osteocalcin mRNA, TGFß1 mRNA, type I collagen mRNA, and osteonectin mRNA were determined by Northern analysis as previously described (17). The probes used were: rat osteocalcin pR 22–11, an EcoR insert in pSP65 (18), provided by Dr. S. Rossi-Langer, Genetics Institute, Cambridge, MA; rat TGFß1 cloned in pBluescript II KS+ vector excisable with HindIII and XbaI (19), provided by Dr. M. Sporn, Dartmouth Medical School, Hanover NH; rat prepro-{alpha}-2-chain of type I collagen, a 1600-bp-length fragment inserted into the PstI site of the plasmid vector pBR 322 (20), provided by Dr. C. Genovese, University of CT, Farmington, CT; and pH VON-9–2 plasmid DNA containing a 546-bp human osteonectin complementary DNA (cDNA) insert (21), obtained from Dr. G. Long, University of Vermont, Burlington, Vermont.

TGFß1 mRNA, TGFß2 mRNA, TGFß3 mRNA, and glyceride-3-phosphate dehydrogenase mRNA in extracts of long-bone metaphyses were assessed with ribonuclease (RNase) protection with a mCK-3 kit (Pharmagen, San Diego, CA). The probe set was hybridized to the target RNAs in excess, and free probe was digested with RNases. Remaining hybridized/RNase-protected probes were purified, sorted by size on a denaturing polyacrylamide gel, and autoradiographed. The quantity of each RNA species was based on signal intensities of the resulting bands and was normalized against glyceride-3-phosphate dehydrogenase. Densitometric values were determined by a phosphoimager (Molecular Dynamics, Sunnyvale, CA) and were analyzed by ImageQuant PC-based software (Molecular Dynamics).

Analysis of serum chemistry
Serum calcium (22) and phosphorus (23) were measured by automated colorimetric procedures. Serum testosterone was measured by RIA (24).

Statistical analysis
Results are presented as means ± SE. Significant differences were determined by Student’s nonpaired t test and by one-way ANOVA.


   Results
Top
 Abstract
 Introduction
 Materials and Methods
 Results
Discussion
 References
 
Orchiectomized rats gained significantly less weight than sham-operated animals, and testosterone replacement only partially compensated for this difference (Table 1Go). Orchiectomy reduced serum testosterone and serum phosphate, and these decreases were prevented by testosterone replacement (Table 2Go). Serum calcium was not altered.


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  		Table 1. Effects of orchiectomy and testosterone replacement on body weight

 

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  		Table 2. Effects of orchiectomy and testosterone replacement on serum values

 
The skeletal concentrations of total TGFß and each of the three isoforms of the growth factor were reduced by more than 80% in extracts of bone, 6 weeks after orchiectomy, and reductions were prevented by testosterone replacement (Fig. 1Go). Studies with neutralizing antibodies to TGFß1, TGFß2, and TGFß3 indicated that all three isoforms were present in extracts of bone, that the concentration of TGFß1 was much greater than that of the other two isoforms, and that the relative concentrations of the three isoforms were the same in sham-operated, orchiectomized, and orchiectomized rats given testosterone (Fig. 1Go).



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  		Figure 1. Effects of orchiectomy and T replacement on isoforms of TGFß in long bones. Results are mean ± SE of four to six animals. Rats underwent sham operation (sham) or orchiectomy and, a week later, were given either placebo or 100 mg testosterone in 60-day slow-release pellets implanted sc at the back of the neck. Animals were killed 6 weeks after surgery. Orchiectomy significantly reduced the concentration by over 80% of total TGFß (P < 0.0001), TGFß1 (P < 0.0001), TGFß2 (P < 0.0001), and TGFß3 (P < 0.0002). T replacement increased the concentration of total TGFß and isoforms of TGFß so that these and sham-operated values were not different from each other. Bones were extracted and TGFß activity was determined by the mink lung cell bioassay with TGFß2 as the standard, as described in the text. To determine isoforms, extracts of long bones were cultured with or without neutralizing antibodies to either TGFß1, TGFß2, or TGFß3. TGFß was assessed by inhibition of growth of mink lung cells. Activity with no antibody was 100% inhibition. Growth with no TGFß was 100%. Neutralizing antibodies prevented inhibition of growth by TGFß that was present in the extracts. In the bioassay, there were eight samples for each standard and each unknown sample.

 
TGFß1 mRNA was not altered in either cortical or cancellous bone, 4 weeks after orchiectomy (Table 3Go). In keeping with the relative concentrations of TGFß1 and TGFß2 in extracts of long bones, TGFß1 mRNA was greater than TGFß2 mRNA; and 4 weeks after orchiectomy, TGFß1 mRNA and TGFß2 mRNA in metaphyseal bone were not altered (Table 4Go). In the latter study, TGFß3 mRNA was below the limit of detection. These findings indicate that reduction in TGFß activity after orchiectomy occurs at a posttranscriptional level.


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  		Table 3. Effects of orchiectomy on mRNA of TGFß1 and osteocalcin in long bones

 

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  		Table 4. Effects of orchiectomy on mRNA of TGFß1 and TGFß2 in long bones

 
Osteocalcin mRNA from cancellous bone, type I collagen mRNA from cortical bone, and osteocalcin mRNA from cortical bone were not changed (Tables 3Go and 5Go). In contrast, there was a significant increase in osteocalcin mRNA in cortical bone after orchiectomy, and TGFß1 mRNA was not altered (Table 3Go, Fig. 2Go).


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  		Table 5. Effects of orchiectomy on mRNA of type I collagen and osteonectin in long bones

 


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  		Figure 2. Effects of orchiectomy on mRNA for TGFß1 and osteocalcin (a) and 18S (b) in cancellous bone of the tibia of rats. mRNA was prepared from tibia of three rats in each group, as described in the text.

 

   Discussion
Top
 Abstract
 Introduction
 Materials and Methods
 Results
 Discussion
References
 
The present findings indicate that TGFß is markedly reduced in extracts of bone from orchiectomized rats and that reduction is prevented by testosterone replacement. Whereas TGFß1 is the major isoform of the cytokine in extracts of bone, the concentration of all three isoforms is reduced by orchiectomy, and reductions are prevented by testosterone replacement.

Previous studies demonstrated that TGFß is produced by osteoblasts and osteoblast-like cells (13, 14, 15, 25) and that synthesis is increased by testosterone and dihydrotestosterone (14, 15). Production of TGFß by human bone cells is enhanced by androgens without alteration of TGFß1 mRNA (15). These results and the present findings that TGFß1 mRNA and TGFß2 are not altered by orchiectomy provide evidence that regulation of abundance of TGFß1 and TGFß2 in bone matrix occurs posttranscriptionally.

TGFß is stored in bone matrix and released during resorption (26). As indicated already, TGFß has major effects on the skeleton: it increases bone formation (4, 5, 6), inhibits bone resorption and formation of osteoclast-like cells (27, 28), is chemotactic for osteoblasts and osteoblast-like cells (29), and is involved in bone induction and skeletal repair (7, 8).

As noted, testosterone deficiency in the rat is associated with loss of cancellous bone of the tibia, and loss is prevented by testosterone (1, 2, 3). Because the concentrations of total TGFß and isoforms of TGFß in extracts of cortical long bones is reduced by over 80% and loss is prevented by testosterone, it is possible that deficiency of TGFß may contribute to or is responsible for bone loss caused by testosterone deficiency. In similar studies in female rats, ovariectomy reduced the concentration of TGFß in extracts of long bones by some 50%, and the decreases were prevented by 17ß-estradiol (13). Bone turnover is increased in ovariectomized rats, and short-term infusion of TGFß2 into the marrow cavity of the femur decreased osteoclast number and bone resorption (30).

The decrease in serum phosphorus produced by orchiectomy confirms previous findings in aging rats (3). The increase in osteocalcin mRNA of cortical bone is consistent with increases in serum osteocalcin and skeletal remodeling produced by orchiectomy in old rats (3).

In summary, our studies show that orchiectomy markedly reduces the skeletal concentrations of the three isoforms of TGFß, that TGFß1 is the predominant skeletal isoform, and that the relative concentrations of the three isoforms of the cytokine are not altered by either orchiectomy or testosterone replacement. In view of the multiple effects of TGFß on bone metabolism, it is possible that deficiency of TGFß plays a role in the pathogenesis of bone loss that occurs in testosterone-deficient states.


   Acknowledgments
 
We thank V. A. Greene and Minzhi Zhang for expert technical assistance.


   Footnotes
 
1 This work was supported, in part, by the Department of Veterans Affairs and NIH Grants AR-35651 and AR-41418 (to R.T.T.). Back

2 Was on sabbatical from the Department of Physiological Sciences, University of Florida College of Veterinary Medicine, Gainesville, Florida 32610. Back

Received July 3, 1997.


   References
Top
 Abstract
 Introduction
 Materials and Methods
 Results
 Discussion
 References
 

  1. Turner RT, Hannon KS, Demers LM, Buchanan J, Bell NH 1989 The effects of fluoride on bone and implant histomorphometry in growing rats. J Bone Miner Res 4:477–484[Medline]
  2. Wakley GK, Schritte HD, Hannon KS, Turner RT 1991 Androgen treatment prevents loss of cancellous bone in the orchiectomized rat. J Bone Miner Res 6:325–330[Medline]
  3. Vanderschueren D, Van Herck E, Suiker AMH, Visser WJ, Schot LPC, Bouillon R 1992 Bone and mineral metabolism in aged male rats: short and long term effects of androgen deficiency. Endocrinology 130:2906–2916[Abstract]
  4. Mackie EJ, Trechsel U 1990 Stimulation of bone formation in vivo by transforming growth factor-beta: remodeling of woven bone and lack of inhibition by indomethacin. Bone 11:295–300[Medline]
  5. Noda M, Camilliere JJ 1986 In vivo stimulation of bone formation by transforming growth factor-beta. Endocrinology 124:56–65
  6. Joyce ME, Roberts AB, Sporn MB, Bolander ME 1990 Transforming growth factor-beta and the initiation of chondrogenesis and osteogenesis in the rat femur. J Cell Biol 110:2195–2207[Abstract/Free Full Text]
  7. Joyce ME, Terek RM, Jungushi S, Bolander ME 1990 Role of transforming growth factor-beta in fracture repair. Ann NY Acad Sci 593:107–123[CrossRef][Medline]
  8. Rosen D, Miller SC, DeLeon E, Thompson AY, Bentz H, Mathews M, Adams S 1994 Systemic administration of recombinant transforming growth factor beta 2 (rTGF-beta 2) stimulates parameters of cancellous bone formation in juvenile and adult rats. Bone 15:355–359[Medline]
  9. Bentz H, Nathan RM, Rosen DM, Armstrong RM, Thompson AY, Segarini PR, Mathews MC, Dasch JR, Piez KA, Seyedin SM 1989 Purification and characterization of a unique osteoinductive factor from bovine bone. J Biol Chem 264:20805–20810[Abstract/Free Full Text]
  10. Turner RT, Farley J, Vandersteenhoven JJ, Epstein S, Bell NH, Baylink DJ 1988 Demonstration of reduced mitogenic and osteoinductive activities in demineralized allogeneic bone matrix from vitamin D-deficient rats. J Clin Invest 82:212–217
  11. Finkelman RD, Linkhart TA, Mohan S, Lau KHW, Baylink DJ, Bell NH 1991 Vitamin D deficiency causes a selective reduction in deposition of transforming growth factor beta in rat bone: possible mechanism for impaired osteoinduction. Proc Natl Acad Sci USA 88:3657–3660[Abstract/Free Full Text]
  12. Cesnjaj M, Stavljenic A, Vukicevic S 1991 Decreased osteoinductive potential of bone matrix from ovariectomized rats. Acta Orthop Scand 62:471–475[Medline]
  13. Finkelman RD, Bell NH, Strong DD, Demers LM, Baylink DJ 1992 Ovariectomy selectively reduces the concentration of transforming growth factor beta in rat bone: implications for estrogen deficiency-associated bone loss. Proc Natl Acad Sci USA 89:12190–12193[Abstract/Free Full Text]
  14. Kasperk C, Fitzsimmons R, Strong D, Mohan S, Jennings J, Wergedal J, Baylink DJ 1990 Studies of the mechanism by which androgens enhance mitogenesis and differentiation in bone cells. J Clin Endocrinol Metab 71:1322–1329[Abstract]
  15. Bodine PV, Riggs BL, Spelsberg TC 1995 Regulation of c-fos expression and TGF-beta production by gonadal and adrenal androgens in normal human osteoblastic cells. J Steroid Biochem Mol Biol 52:149–158[CrossRef][Medline]
  16. Ogawa Y, Seyedin SM 1991 Purification of transforming growth factors beta 1 and beta 2 from bovine bone and cell culture assays. Methods Enzymol 198:317–327[Medline]
  17. Westerlind KC, Wronske TJ, Evans GL, Turner R 1994 The effect of long-term ovarian hormone deficiency on transforming growth factor-beta and bone matrix protein mRNA expression in rat femora. Biochem Biophys Res Commun 200:283–289[CrossRef][Medline]
  18. Celeste AJ, Rosen V, Buecker JL, Kriz R, Wang EA, Wozney JM 1986 Isolation of the human gene for bone gla protein utilizing mouse and rat cDNA clones. EMBO J 5:1885–1890[Medline]
  19. Derynck R, Jarrett JA, Chen Y, Eaton DH, Bell JR, Assoian RK, Roberts AB, Sporn MB, Goeddel DV 1985 Human transforming growth factor-beta complementary DNA sequence and expression in normal and transformed cells. Nature 316:701–704[CrossRef][Medline]
  20. Genovese C, Rowe D, Kream B 1984 Construction of DNA sequences complementary to rat alpha 1 and alpha 2 collagen mRNA and their use in studying the regulation of type I collage synthesis by 1,25-dihydroxyvitamin D. Biochemistry 23:6210–6216[CrossRef][Medline]
  21. Villareal XC, Mann KG, Long GL 1989 Structure of human osteonectin based upon analysis of cDNA and genomic sequences. Biochemistry 28:6483–6491[CrossRef][Medline]
  22. Connerty HV, Briggs AR 1966 Determination of serum calcium by means of orthocresolphthalein complexone. Am J Clin Pathol 45:290–296[Medline]
  23. Daly JA, Ertinghausen G 1972 Direct method for determining inorganic phosphate in serum with the "CentrifiChem". Clin Chem 18:263–265[Abstract]
  24. Testosterone. Mini-Seminar 1982 Diagnostics Products Corporation 5:2
  25. Oursler MJ, Cortese C, Keeting PE, Anderson MA, Bonde SK, Riggs BL, Spelsberg TC 1991 Modulation of transforming growth factor-beta production in normal human osteoblast-like cells by 17 beta-estradiol and parathyroid hormone. Endocrinology 129:3313–3320[Abstract]
  26. Pfeilschifter J, Mundy GR 1987 Modulation of type beta transforming growth factor activity in bone cultures by osteotropic hormones. Proc Natl Acad Sci USA 84:2024–2028[Abstract/Free Full Text]
  27. Pfeilschifter JP, Seyedin S, Mundy GR 1988 Transforming growth factor beta inhibits bone resorption in fetal rat long bone cultures. J Clin Invest 82:680–685
  28. Chenu C, Pfeilschifter J, Mundy GR, Roodman GD 1988 Transforming growth factor beta inhibits formation of osteoclast-like cells in long-term human marrow cultures. Proc Natl Acad Sci USA 85:5683–5687[Abstract/Free Full Text]
  29. Pfeilschifter J, Wolf O, Naumann A, Minne HW, Mundy GR, Ziegler R 1990 Chemotactic response of osteoblast-like cells to transforming growth factor beta. J Bone Miner Res 5:825–830[Medline]
  30. Beaudreuil J, Mbalaviele G, Cohen-Solal M, Morieux C, de Vernejoul MC, Orcel P 1995 Short-term local injections of transforming growth factor-beta 1 decrease ovariectomy-stimulated osteoclastic resorption in vivo in rats. J Bone Miner Res 10:971–977[Medline]



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