Relaxin stimulates the synthesis and release of prorenin from human decidual cells: Evidence for autocrine/paracrine regulation

Porcine relaxin caused a time- and concentration-dependent increase in the release of renin from decidual cells cultured over a 96 h period. The increase in renin release occurred 24–48 h after exposure and was maximal at 48–72 h. Half-maximal stimulation occurred at a relaxin concentration of 5 ng/ml, and maximal stimulation (250–270%) occurred at concentrations ≧ 10 ng/ml. At each time, > 95% of the renin released into the medium was in the form of prorenin. The stimulation of renin release was paralleled by a stimulation of cellular renin content and was completely inhibited by cycloheximide, indicating that relaxin also stimulated renin synthesis. Since renin is present in both cytotrophoblast and decidual cells, these results suggest a paracrine and/or autocrine relationship between relaxin- and prorenin-secreting cells.