Structural and functional effects of high prolactin levels on injured endothelial cells - Evidence for an endothelial prolactin receptor

Stress has been linked to health problems such as atherosclerosis and prolo nged wound healing, which involve the responses of injured endothelial cell s. Though prolactin (PRL) levels become increased during the physiological response to stress, the significance and effects of these increases are lar gely unknown. Here we examined the effects of elevated, though physiologica l, concentrations of PRL on the responses of cultured endothelial cells aft er mechanical injury to cell monolayers, When treated at the time of injury with PRL levels of 62.5-1000 ng/mL, cells at the wound front became abnorm al in shape and had reductions in f-actin staining in comparison to control s that were not PRL-treated. High PRL concentrations also inhibited the adh esion of cells to their growth surface in a dose-dependent manner. Using rh odamine-labeled PRL, we observed specific PRL uptake by these cells that su ggested the presence of a PRL receptor. Finally, mRNA for the long form of the PRL receptor was detected by RT-PCR, To our knowledge, this is the firs t report demonstrating that (1) high PRL concentrations alter the actin cyt oskeleton and adhesion of injured endothelial cells and (2) endothelial cel ls express the transcript for the PRL receptor. Thus, we report novel effec ts of PRL that may be mediated by activation of an endothelial cell PRL rec eptor.