The role of estrogen in osteogenetic cytokine expression in human periodontal ligament cells.

The purpose was to identify the effects of estrogen on the expression of alkaline phosphatase (ALP) and osteoprotegerin (OPG) in human periodontal ligament cells (hPDLCs). Cells were obtained from healthy periodontal tissue explants of teeth that had been extracted for orthodontic reasons. ALP activity was determined after 17b-estradiol (17b-E2) treatment at 0, 0.1, 1, 10, and 100 nmol/L by using assay reagents. OPG expression in hPDLCs was studied by enzyme-linked immunosorbent assay and reverse-transcriptase polymerase chain reaction. It was shown that the ALP activity and the OPG protein production were increased in a time-dependent manner (P < .05). Whereas a physiologic concentration of 17b-E2 enhanced the secretion of OPG (P < .05) and the expression of OPG mRNA, a high dose (100 nmol/L) of 17b-E2 had no such effect on hPDLCs. It appears that estrogen may exert its antiresorptive effects and maintain periodontal health through stimulating ALP and OPG expression in hPDLCs. (Int J Periodontics Restorative Dent 2009;29:507-513.).