Limits...
The effect of oxandrolone treatment on human osteoblastic cells.

Bi LX, Wiren KM, Zhang XW, Oliveira GV, Klein GL, Mainous EG, Herndon DN - J Burns Wounds (2007)

Bottom Line: Alkaline phosphatase (7%-20%) and osteocalcin (13%-18%) increases were modest but significant.Short-term treatment produced no significant effects, but at 5 days androgen receptor levels were increased while collagen levels were significantly decreased, with little effect on alkaline phosphatase, osteocalcin, or osteoprotegerin.These data suggest oxandrolone can stimulate production of osteoblast differentiation markers in proliferating osteoblastic cells, most likely through the androgen receptor; however, with longer treatment in mature cells, oxandrolone decreases collagen expression.

View Article: PubMed Central - PubMed

Affiliation: Department of Oral and Maxillofacial Surgery, University of Texas Medical Branch, Galveston, TX, USA. lbi@utmb.edu

ABSTRACT

Objective: Oxandrolone, administered to severely burned children over the first year postburn, produces increased lean body mass by 6 months; however, an increase in total body bone mineral requires 12 months. Consequently, this bone mineral response may be due to increased muscle mass. Alternatively, oxandrolone may act directly on bone. The current study seeks to determine whether oxandrolone can transactivate the androgen receptor in osteoblasts.

Methods: Collagen, alkaline phosphatase, osteocalcin, osteoprotegerin, and androgen receptor abundance were determined by qRT-PCR, confocal laser scanning microscopy, or immunoquantitative assay. To determine the effect of oxandrolone on gene expression in differentiated cells, osteocytic cultures were grown to confluence in differentiation medium and then treated 24 hours or 5 days with 15 microg/mL oxandrolone.

Results: Increased nuclear fluorescence of the androgen receptor and increased cellular type I collagen were observed with oxandrolone at 15 and 30 microg/mL but not at lower doses. Alkaline phosphatase (7%-20%) and osteocalcin (13%-18%) increases were modest but significant. Short-term treatment produced no significant effects, but at 5 days androgen receptor levels were increased while collagen levels were significantly decreased, with little effect on alkaline phosphatase, osteocalcin, or osteoprotegerin.

Conclusions: These data suggest oxandrolone can stimulate production of osteoblast differentiation markers in proliferating osteoblastic cells, most likely through the androgen receptor; however, with longer treatment in mature cells, oxandrolone decreases collagen expression. Thus it is possible that oxandrolone given to burned children acts directly on immature osteoblasts to stimulate collagen production, but also may have positive effects to increase bone mineral through other mechanisms.

No MeSH data available.


Related in: MedlinePlus

Consequence of oxandrolone treatment on gene expression in normal human osteocytes: dose-response analysis. Normal human osteoblastic cells were cultured as described in Figure 5. Osteocytic cultures were treated for 5 days with 0, 1, 5, 10, and 15 μg/mL oxandrolone. Total RNA was isolated and gene expression characterized by qRT-PCR analysis using human primers specific for AR, type I collagen (col), alkaline phosphatase (ALP), osteocalcin (OC) and osteoprotegerin (OPG). n = 2 to 4. *P < .05; **P < .01.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC1828036&req=5

Figure 6: Consequence of oxandrolone treatment on gene expression in normal human osteocytes: dose-response analysis. Normal human osteoblastic cells were cultured as described in Figure 5. Osteocytic cultures were treated for 5 days with 0, 1, 5, 10, and 15 μg/mL oxandrolone. Total RNA was isolated and gene expression characterized by qRT-PCR analysis using human primers specific for AR, type I collagen (col), alkaline phosphatase (ALP), osteocalcin (OC) and osteoprotegerin (OPG). n = 2 to 4. *P < .05; **P < .01.

Mentions: AR concentrations increase as osteoblasts differentiate, reaching their highest levels in osteocytic cultures.13 Furthermore, the most abundant cell in bone is the osteocytic cell. We therefore determined the effect of oxandrolone treatment on gene expression in mature osteocytic cultures. Normal human osteoblasts were cultured for 10 days, then switched to differentiation medium containing ascorbic acid and β-glycerol phosphate. After 7 days, osteocytic cells were treated with 15 μg/mL oxandrolone. Total RNA was isolated after 24 hours or 5 days treatment, and gene expression characterized by qRT-PCR analysis using human primers specific for AR, type I collagen, alkaline phosphatase, osteocalcin, and osteoprotegerin (Fig 5). Although there was little effect of oxandrolone after 24 hours of treatment in osteocytic cells on type I collagen, alkaline phosphatase, osteocalcin, or osteoprotegerin mRNA abundance, a nonsignificant increase in AR mRNA was noted. This is consistent with other reports documenting an increase in AR after androgen treatment in osteoblasts.14 After stimulation with oxandrolone for 5 days, a significant decrease in expression of type I collagen was seen (P < 0.01). Thus, longer treatments with oxandrolone in osteocytic cultures reduced collagen expression. These data are consistent with dose-response studies performed after 5 days of treatment with increasing concentrations of oxandrolone (Fig 6), where AR mRNA is modestly increased but collagen levels are significantly decreased in a dose-dependent fashion with oxandrolone treatment.


The effect of oxandrolone treatment on human osteoblastic cells.

Bi LX, Wiren KM, Zhang XW, Oliveira GV, Klein GL, Mainous EG, Herndon DN - J Burns Wounds (2007)

Consequence of oxandrolone treatment on gene expression in normal human osteocytes: dose-response analysis. Normal human osteoblastic cells were cultured as described in Figure 5. Osteocytic cultures were treated for 5 days with 0, 1, 5, 10, and 15 μg/mL oxandrolone. Total RNA was isolated and gene expression characterized by qRT-PCR analysis using human primers specific for AR, type I collagen (col), alkaline phosphatase (ALP), osteocalcin (OC) and osteoprotegerin (OPG). n = 2 to 4. *P < .05; **P < .01.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC1828036&req=5

Figure 6: Consequence of oxandrolone treatment on gene expression in normal human osteocytes: dose-response analysis. Normal human osteoblastic cells were cultured as described in Figure 5. Osteocytic cultures were treated for 5 days with 0, 1, 5, 10, and 15 μg/mL oxandrolone. Total RNA was isolated and gene expression characterized by qRT-PCR analysis using human primers specific for AR, type I collagen (col), alkaline phosphatase (ALP), osteocalcin (OC) and osteoprotegerin (OPG). n = 2 to 4. *P < .05; **P < .01.
Mentions: AR concentrations increase as osteoblasts differentiate, reaching their highest levels in osteocytic cultures.13 Furthermore, the most abundant cell in bone is the osteocytic cell. We therefore determined the effect of oxandrolone treatment on gene expression in mature osteocytic cultures. Normal human osteoblasts were cultured for 10 days, then switched to differentiation medium containing ascorbic acid and β-glycerol phosphate. After 7 days, osteocytic cells were treated with 15 μg/mL oxandrolone. Total RNA was isolated after 24 hours or 5 days treatment, and gene expression characterized by qRT-PCR analysis using human primers specific for AR, type I collagen, alkaline phosphatase, osteocalcin, and osteoprotegerin (Fig 5). Although there was little effect of oxandrolone after 24 hours of treatment in osteocytic cells on type I collagen, alkaline phosphatase, osteocalcin, or osteoprotegerin mRNA abundance, a nonsignificant increase in AR mRNA was noted. This is consistent with other reports documenting an increase in AR after androgen treatment in osteoblasts.14 After stimulation with oxandrolone for 5 days, a significant decrease in expression of type I collagen was seen (P < 0.01). Thus, longer treatments with oxandrolone in osteocytic cultures reduced collagen expression. These data are consistent with dose-response studies performed after 5 days of treatment with increasing concentrations of oxandrolone (Fig 6), where AR mRNA is modestly increased but collagen levels are significantly decreased in a dose-dependent fashion with oxandrolone treatment.

Bottom Line: Alkaline phosphatase (7%-20%) and osteocalcin (13%-18%) increases were modest but significant.Short-term treatment produced no significant effects, but at 5 days androgen receptor levels were increased while collagen levels were significantly decreased, with little effect on alkaline phosphatase, osteocalcin, or osteoprotegerin.These data suggest oxandrolone can stimulate production of osteoblast differentiation markers in proliferating osteoblastic cells, most likely through the androgen receptor; however, with longer treatment in mature cells, oxandrolone decreases collagen expression.

View Article: PubMed Central - PubMed

Affiliation: Department of Oral and Maxillofacial Surgery, University of Texas Medical Branch, Galveston, TX, USA. lbi@utmb.edu

ABSTRACT

Objective: Oxandrolone, administered to severely burned children over the first year postburn, produces increased lean body mass by 6 months; however, an increase in total body bone mineral requires 12 months. Consequently, this bone mineral response may be due to increased muscle mass. Alternatively, oxandrolone may act directly on bone. The current study seeks to determine whether oxandrolone can transactivate the androgen receptor in osteoblasts.

Methods: Collagen, alkaline phosphatase, osteocalcin, osteoprotegerin, and androgen receptor abundance were determined by qRT-PCR, confocal laser scanning microscopy, or immunoquantitative assay. To determine the effect of oxandrolone on gene expression in differentiated cells, osteocytic cultures were grown to confluence in differentiation medium and then treated 24 hours or 5 days with 15 microg/mL oxandrolone.

Results: Increased nuclear fluorescence of the androgen receptor and increased cellular type I collagen were observed with oxandrolone at 15 and 30 microg/mL but not at lower doses. Alkaline phosphatase (7%-20%) and osteocalcin (13%-18%) increases were modest but significant. Short-term treatment produced no significant effects, but at 5 days androgen receptor levels were increased while collagen levels were significantly decreased, with little effect on alkaline phosphatase, osteocalcin, or osteoprotegerin.

Conclusions: These data suggest oxandrolone can stimulate production of osteoblast differentiation markers in proliferating osteoblastic cells, most likely through the androgen receptor; however, with longer treatment in mature cells, oxandrolone decreases collagen expression. Thus it is possible that oxandrolone given to burned children acts directly on immature osteoblasts to stimulate collagen production, but also may have positive effects to increase bone mineral through other mechanisms.

No MeSH data available.


Related in: MedlinePlus