Long-term selective estrogen receptor-beta agonist treatment modulates gene expression in bone and bone marrow of ovariectomized rats

Gonadal hormones including 17 beta-estradiol exert important protective functions in skeletal homeostasis. However, numerous details of ovarian hormone deficiency in the common bone marrow microenvironment have not yet been revealed and little information is available on the tissue -specific acts either, especially those via estrogen receptor beta (ER beta). The aim of the present study was therefore to examine the bone -related gene expression changes after ovariectomy (OVX) and long-term ER beta agonist diarylpropionitrile (DPN) administration. We found that OVX produced strong and widespread changes of gene expression in both femoral bone and bone marrow. In the bone out of 22 genes, 20 genes were up- and 2 were downregulated after OVX. It is noteworthy that DPN restored mRNA expression of 10 OVX-induced changes (A1c1112, Collal, Daaml, FgfI2, Igfl, I16r, Nfkbl, Notchl, Notch2 and Psenl) suggesting a modulatory role of EFt13 in bone physiology. In bone marrow, out of 37 categorized genes, transcription of 25 genes were up- and 12 were downregulated indicating that the marrow is highly responsive to gonadal hormones. DPN modestly affected transcription, only expression of two genes (Nfatci and Tgfbl) was restored by DPN action. The PI3K/Akt signaling pathway was the most affected gene cluster following the interventions in bone and bone marrow, as demonstrated by canonical variates analysis (CVA). We suggested that our results contribute to a deeper understanding of alterations in gene expression of bone and bone marrow niche elicited by ER beta and selective ER beta analogs.