Age- and sex-dependent hormonal modulation of the expression of vitamin D receptor and 25-hydroxyvitamin D 1α hydroxylase in human bone cells.

Background: Human cultured osteoblasts from pre-Ob, post-Ob or m-Ob express different mRNAs and respond to different hormones.

Aims: To test expression and hormonal modulation of VDR and 1OHase and 1,25D production in hObs.

Methods: hObs obtained from bone explants were prepared, treated and analyzed as before.

Results: (i) VDR and 1OHase were expressed in all hObs. (ii) 1,25D was produced similarly. (iii) Treatment with E, DPN (ER agonist), but not PPT (ER agonist) increased VDR. (iv) These hormones increased 1OHase. (v) Vitamin D analog JKF and PTH 1-84 increased similarly mRNAs. (vi) Treatment with E, DPN and PPT increased 1,25D. (vii) JKF and PTH increased similarly 1,25D. (viii) DNA synthesis and CK were stimulated by all hormones in hObs.

Conclusions: Hormonal modulation of VDR and 1OHase and 1,25D production is important for bone physiology but their correlation, activity and bone physiology is not yet clear.