Effects of parathyroid hormone and estradiol on proliferation and function of human osteoblasts from fetal long bone. An in vitro study.

The effect of parathyroid hormone (PTH) (0.01 nM-10 nM) and 17 beta-estradiol (E2, 1 nmol-10 nM) alone or in combination on 3H-thymidine incorporation, alkaline phosphatase and adenylate cyclase activities were investigated in human fetal osteoblasts using serum-free monolayer primary cultures. The results showed that PTH inhibited cell proliferation while E2 promoted it. On alkaline phosphatase activity, PTH showed a complex results while E2 were slightly inhibitory. PHT-E2 combination suggested that E2 could alter the effect of PTH alone, also potentiated the anabolic and antagonize the catabolic effects of PTH on bone formation.