Oxytocin (OT) is present in reproductive tissues of male mammals including human prostate tissue. OT increases prostatic muscle tone and prostatic growth. OT is increased in benign prostatic hyperplasia (BPH), an androgen dependent condition that develops with age. Dihydrotestosterone (DHT) is the active hormone in the prostate and is converted from testosterone by the enzyme 5 a reductase. Conversion has been shown to be augmented in the presence of OT. The aim of this study was to investigate the effect of oxytocin on cell growth and steroid production in cultured normal human prostate cells.
Normal human prostate stromal and epithelial cells (Clonetics) were cultured with OT, oxytocin antagonist (OTA) or oxytocin/oxytocin antagonist combination (10 ng/mL, 1 ng/mL or 0.1 ng/mL) in media containing 10 nmol of testosterone. Media was changed daily over the 5 day growth period and frozen. Cell proliferation assay was performed at harvest on day 5 to ascertain cell numbers. Media from days 1, 3 and 5 were extracted and radioimmunoassayed for testosterone and DHT.
OT increased stromal cell number in a dose dependent manner (P < 0.001). Treatment with OT or OTA had no significant effect on epithelial cell numbers. In stromal cell media from Day 1, DHT concentrations were higher in cells treated with OT than control cells (P < 0.05). By Day 5 the concentration of DHT was low in all treatment groups except OT (10 ng/mL). No effect of OT or OTA was seen on DHT concentrations of media from epithelial cells.
OT may increase cell growth in prostate stromal cells but not epithelial cells grown in vitro. This effect may be related to the conversion of testosterone to DHT and DHT to its metabolites. These results demonstrate that OT may play a role in the regulation of cell growth, steroid production and steroid metabolism in the human prostate.
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