Prostate expression of endothelins and their receptors in rat growth

Endothelins (ETs) have been shown to have mitogenic effects on prostate cells in vitro. To study a relationship between ETs and prostate growth, we investigated expression of ET-1 and ET-3 and their receptors ETA and ETB in the dorsolateral (DLP) and ventral (VP) prostate lobes of rats aged 3 weeks, 3 months, and 22 months. The weight ratio of each lobe to the body was not different at 3 weeks but increased more in the DLP than in the VP at 3 months; the ratio did not change at 22 months. The density of the major receptor ETA, measured by radio-labelled ET-1 binding to prostate membrane particulates, was highest at 3 weeks in both prostate lobes and decreased thereafter. mRNA expression levels of ETA, ETB, ET-1, and ET-3 in the DLP and ETA in the VP, as assessed by relative multiplex reverse transcription-polymerase chain reaction, were highest at 3 weeks, and no significant change was seen in mRNA expression of ET-converting enzyme-1. The highest expression of ETA and the ligands at 3 weeks, followed by dramatic growth at 3 months in the DLP, suggests a role of ETA-mediated signal transduction in prostate growth of rats and possibly of humans.