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Androgen prevents hypogonadal bone loss via inhibition of resorption mediated by mature osteoblasts/osteocytes.
Bone 2012; 51(5):835-46BONE

Abstract

Androgen receptor (AR) is expressed throughout the osteoblast lineage. Two different AR transgenic families (AR2.3-tg and AR3.6-tg mice) demonstrating overlapping and distinct expression profiles were employed to assess the effects of enhanced androgen sensitivity to ameliorate hypogonadal loss. Two different paradigms of steroid replacement following orchidectomy (ORX) were used as either preventative or therapeutic therapy. ORX was performed in male wild-type (WT), AR2.3-tg and AR3.6-tg mice at 5 months with immediate DHT replacement (prevention, higher turnover) or at 3 months with DHT treatment delayed for 2 months (therapeutic, lower turnover), both with treatment for the last 6 weeks. Dual energy X-ray absorptiometry (DXA), micro-computed tomography (μCT), and histomorphometry were performed. In the prevention model, ORX significantly reduced BMD and BMC in all genotypes compared to sham and DHT was effective at prevention of osteopenia. In the therapeutic model, all genotypes became osteopenic compared to sham, but after a prolonged hypogonadal period, delayed DHT treatment provided little benefit. μCT analysis of mid-shaft total bone in all genotypes generally showed reductions after ORX. Delayed DHT was ineffective at restoring bone volume in any genotype whereas immediate treatment prevented loss only in AR transgenic mice. Cortical thickness also decreased with ORX but immediate DHT treatment was effective to increase thickness only in WT mice, likely due to expansion of marrow volume in both AR-tg lines. In metabolically highly active cancellous bone, ORX resulted in lower bone volume/tissue volume (BV/TV) in all genotypes, consistent among 3 sites measured. Again with delayed treatment, there was little effect of DHT to restore BV/TV, but when administered at the time of ORX, DHT completely prevented the decrease in cancellous bone in all genotypes. Improvement in cancellous bone architecture was seen with immediate DHT replacement that was enhanced in AR transgenic lines compared to WT. In contrast, there were only modest changes in all genotypes using the delayed treatment paradigm. With ORX in both paradigms, trabecular number was decreased while spacing increased. Thus, androgen therapy is effective for the prevention of endosteal and cancellous osteopenia primarily through its anti-resorptive properties, but shows little anabolic action as a therapeutic strategy to restore bone. Given the similarity in response to androgen treatment in both AR transgenic lines, overlapping expression profiles suggest that the target cells mediating androgen action in vivo are mature osteoblast/osteocytes. Combined, these results demonstrate that in the adult mouse, androgen treatment can reduce bone resorption but has little overall anabolic activity.

Authors+Show Affiliations

Department of Veterans Affairs Medical Center, Portland, OR 97239, USA. wirenk@ohsu.eduNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, N.I.H., Extramural
Research Support, U.S. Gov't, Non-P.H.S.

Language

eng

PubMed ID

22910580

Citation

Wiren, Kristine M., et al. "Androgen Prevents Hypogonadal Bone Loss Via Inhibition of Resorption Mediated By Mature Osteoblasts/osteocytes." Bone, vol. 51, no. 5, 2012, pp. 835-46.
Wiren KM, Zhang XW, Olson DA, et al. Androgen prevents hypogonadal bone loss via inhibition of resorption mediated by mature osteoblasts/osteocytes. Bone. 2012;51(5):835-46.
Wiren, K. M., Zhang, X. W., Olson, D. A., Turner, R. T., & Iwaniec, U. T. (2012). Androgen prevents hypogonadal bone loss via inhibition of resorption mediated by mature osteoblasts/osteocytes. Bone, 51(5), pp. 835-46. doi:10.1016/j.bone.2012.08.111.
Wiren KM, et al. Androgen Prevents Hypogonadal Bone Loss Via Inhibition of Resorption Mediated By Mature Osteoblasts/osteocytes. Bone. 2012;51(5):835-46. PubMed PMID: 22910580.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Androgen prevents hypogonadal bone loss via inhibition of resorption mediated by mature osteoblasts/osteocytes. AU - Wiren,Kristine M, AU - Zhang,Xiao-Wei, AU - Olson,Dawn A, AU - Turner,Russell T, AU - Iwaniec,Urszula T, Y1 - 2012/08/14/ PY - 2012/05/11/received PY - 2012/07/27/revised PY - 2012/08/06/accepted PY - 2012/8/23/entrez PY - 2012/8/23/pubmed PY - 2013/2/13/medline SP - 835 EP - 46 JF - Bone JO - Bone VL - 51 IS - 5 N2 - Androgen receptor (AR) is expressed throughout the osteoblast lineage. Two different AR transgenic families (AR2.3-tg and AR3.6-tg mice) demonstrating overlapping and distinct expression profiles were employed to assess the effects of enhanced androgen sensitivity to ameliorate hypogonadal loss. Two different paradigms of steroid replacement following orchidectomy (ORX) were used as either preventative or therapeutic therapy. ORX was performed in male wild-type (WT), AR2.3-tg and AR3.6-tg mice at 5 months with immediate DHT replacement (prevention, higher turnover) or at 3 months with DHT treatment delayed for 2 months (therapeutic, lower turnover), both with treatment for the last 6 weeks. Dual energy X-ray absorptiometry (DXA), micro-computed tomography (μCT), and histomorphometry were performed. In the prevention model, ORX significantly reduced BMD and BMC in all genotypes compared to sham and DHT was effective at prevention of osteopenia. In the therapeutic model, all genotypes became osteopenic compared to sham, but after a prolonged hypogonadal period, delayed DHT treatment provided little benefit. μCT analysis of mid-shaft total bone in all genotypes generally showed reductions after ORX. Delayed DHT was ineffective at restoring bone volume in any genotype whereas immediate treatment prevented loss only in AR transgenic mice. Cortical thickness also decreased with ORX but immediate DHT treatment was effective to increase thickness only in WT mice, likely due to expansion of marrow volume in both AR-tg lines. In metabolically highly active cancellous bone, ORX resulted in lower bone volume/tissue volume (BV/TV) in all genotypes, consistent among 3 sites measured. Again with delayed treatment, there was little effect of DHT to restore BV/TV, but when administered at the time of ORX, DHT completely prevented the decrease in cancellous bone in all genotypes. Improvement in cancellous bone architecture was seen with immediate DHT replacement that was enhanced in AR transgenic lines compared to WT. In contrast, there were only modest changes in all genotypes using the delayed treatment paradigm. With ORX in both paradigms, trabecular number was decreased while spacing increased. Thus, androgen therapy is effective for the prevention of endosteal and cancellous osteopenia primarily through its anti-resorptive properties, but shows little anabolic action as a therapeutic strategy to restore bone. Given the similarity in response to androgen treatment in both AR transgenic lines, overlapping expression profiles suggest that the target cells mediating androgen action in vivo are mature osteoblast/osteocytes. Combined, these results demonstrate that in the adult mouse, androgen treatment can reduce bone resorption but has little overall anabolic activity. SN - 1873-2763 UR - https://www.unboundmedicine.com/medline/citation/22910580/Androgen_prevents_hypogonadal_bone_loss_via_inhibition_of_resorption_mediated_by_mature_osteoblasts/osteocytes_ L2 - https://linkinghub.elsevier.com/retrieve/pii/S8756-3282(12)01125-8 DB - PRIME DP - Unbound Medicine ER -