Normal prostate morphology in relaxin-mutant mice

The peptide hormone relaxin is expressed in the prostate gland and secreted into the seminal plasma; however, its function within the prostate has not been established. Relaxin-mutant mice (Rln(-/-)) were reported to have abnormal prostate morphology, but there was no prostate phenotype in relaxin receptor-mutant (Rxfp1(-/-)) mice. The present study aimed to verify the phenotypes in the anterior, dorsal and lateral lobes of the prostate gland of Rln(-/-) and Rxfp1(-/-) mice at different adult ages. Rln(-/-) mice were also treated with relaxin to evaluate the effects of exogenously administered hormone on prostate morphology. Comparisons between these three lobes of the prostate demonstrated no obvious differences in duct morphology, epithelial height or collagen density between Rln(+/+) and Rln(-/-) mice at 2, 4, 6, 8 and 12 months of age. This was similar in Rxfp1(-/-) mice. Relaxin treatment did not affect morphology or epithelial cell height in the different lobes. Furthermore, prostate lobe morphology in transgenic mice overexpressing relaxin Tg(Rln) was not different from the wild-type controls. Rxfp1 was detected in the prostate throughout adult life, but there was no consistent expression of relaxin. In summary, the present study found no evidence to support a prostate phenotype in adult Rln- or Rxfp1- mutant mice.