LOCALIZATION AND EXPRESSION OF THE alpha 1A-1 , alpha 1B AND alpha 1D-ADRENOCEPTORS IN HYPERPLASTIC AND NON-HYPERPLASTIC HUMAN PROSTATE

Abstract

To determine the expression and localization of the alpha1A-1, alpha1B and alpha1D-adrenoceptor (AR) subtypes in hyperplastic and non-hyperplastic human prostate tissue. The expression of the alpha1-AR subtypes was examined at the mRNA level by quantitative solution hybridization, and at the protein level by immunohistochemistry using subtype selective antibodies. While the overall level of alpha1-AR mRNA was not significantly different between hyperplastic and non-hyperplastic tissue, there were significant differences in the ratio of the alpha1-AR subtypes expressed in the two tissue types. The most significant finding from these studies was the reduced expression of the alpha1b-AR mRNA in both glandular and stromal hyperplasia. By immunohistochemistry, the alpha1A-1-AR was detected in the stroma and not in the glandular epithelium. The alpha1B-AR was localized predominantly in the epithelium and was weakly present in the stroma. Lower levels of the alpha1B-AR were detected in the hyperplastic prostatic epithelium. The alpha1D-AR was detected in areas of stroma and was abundantly present in blood vessels. The alpha1A-1-, alpha1B- and alpha1D-AR subtypes are differentially localized in human prostate, and the expression levels of all three subtypes are altered in BPH. Alterations in a1-AR subtype expression (particularly the alpha1B-AR) in BPH cannot be solely attributed to changes in tissue morphometry resulting from hyperplasia and may be of significance in the pathogenesis of BPH.