Senile changes of human prostate-developmental mechanisms of benign prostatic hyperplasia and senile changes in smooth muscle cells in the prostate

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Development of benign prostatic hyperplasia (BPH) partly depend on ageing. We investigated the several issues of 1) morphological changes of human prostate with ageing, 2) functional changes with ageing of smooth muscle cells of the prostate, 3)regulations of epithelial and mesenchymal cells of the prostate by androgen and growth factors. These studies brought us the following results.1) Community-based study for urinary symptoms suggests that development of BPH may involve at least 2 major processes, that is the transition from normal to diffusely enlarged hyperplasia at approximately 50 years of age and subsequent growth through nodular enlarged hyperplasia.2) We established from guinea-pig the cell line of smooth muscles cells, which was confirmed by morphological and functional studies. This cell line may be utilised asan in vitro experimental model.3) Contractile function of smooth muscle of the prostate in aged guinea-pig was reduced, when compared with those of young, suggesting that ageing may affect function of smooth muscle cells.4) Reduced function of bladder smooth muscle was involved in causes of poor voiders with lower urinary tract obstruction by BPH.Agents to make function of bladder smooth muscle improve may be necessary for relief of poor condition of voiding.5) Loss of balance between cell proliferation and apoptosis in the prostate may be involved in development of BPH.Decrease of androgen enhances mRNA expression of transforming growth factor (TGF)-beta in mesenchymal cells in the prostate, resulting in not only loss of epithelial cells by apoptosis but enhanced proliferation of mesenchymal cells mediated by fibroblast growth factor. The latter evidence may be responsible for development of BPH.