The effect of hyperosmotic and sodium chloride hyperosmotic environments on the secretion and synthesis of prolactin from human decidua in vitro.

Using a paired design as well as a cross-over design both with 16 h incubation periods, we have incubated human decidua in hyposmotic, isosmotic, and sodium chloride hyperosmotic media. In the cross-over design each tissue aliquot was subjected to 3 media with different osmolalities, one of which was isosmotic. Thus, intensive utilization of the tissue was possible. The results of the cross-over study were identical with the result of the paired design. We found a decreased secretion of prolactin in hyposmotic environments, whereas hyperosmotic environments up to an osmolality about 400 mmol/kg gave a dose related increase in the prolactin secretion into the medium as well as in the total content of prolactin in the tissue and the medium. Excessive hyperosmotic medium decreased the secretion. The enhanced secretion was an effect of increased production, which could be blocked by cycloheximide. We found no feedback of prolactin on its own secretion.