The in vitro effect of oestradiol on collagen metabolism in metaphyseal rat bone.

Surviving bone pieces from the femoral and tibial metaphyses of young castrated female rats have been incubated for 6 hours with concentrations of oestradiol-17-beta ranging from 10(-9) M to 3 x 10(-5) M, and the in vitro collagen metabolism studied. The addition of oestradiol did not produce any change in the resorption patterns of bone collagen, expressed as release of hydroxyproline to the medium. Parathyroid hormone in the incubation medium increased the resorption and decreased the incorporation rate insignificantly. Addition of both parathyroid hormone and oestradiol to the incubation medium produced a significant increase in resorption and a decrease in incorporation rate as compared with the control incubations. The bone pieces incubated with oestradiol-17-beta 3 x 10(-5) synthesized and incorporated significantly less hydroxyproline than the control bone pieces. This is, however, a very high concentration of the hormone and the physiological significance of the observation is doubtful.