Abstract
Prolactin (LTH) influences calcium regulation. However, its direct effects on calcium transport in cells has not been reported.
In the present study, LTH (200 μg/ml) was shown to have an effect on specific rat cell populations obtained by sequential collagenase digestions of 18-20-day-old fetal calvalia. After 6 days in a routine culture of the cells, the cell populations (P1 Periosteal fibroblast, P2: Osteoblast, P3: Osteocyte) were used for the experiments, at 37°C and pH 7.10±0.02.
In P1, LTH had no effect on the Ca release and uptake. In P2 and P3, LTH decreased the Ca release 20-54% under the control values, and increased the Ca uptake 42-116% over the control values. These effects appeared rapidly within 5 min after the administration of LTH.
Previously, we have reported that LTH-induced effects on the Ca transport in mixed populations of P2 and P3 depend on the concentrations of LTH and also that they increased to approximately twice at 4°C. These results are almost similar to those of parathyroid hormone (PTH).
The present results suggest that LTH have the ability to act directly on organs or cells involved calcium regulation in a manner that is independent of vitamin D.
Part of this study was supported by a grant from the Ministry of Education, Science and Culture of Japan.
