Detection of α1-adrenoceptor subtypes in human hypertrophied prostate byin situ hybridizationsubtypes in human hypertrophied prostate byin situ hybridization

Adrenergic stimulation induces contraction of hypertrophied prostatic tissue via the α1 adrenoceptor, and the results of pharmacological studies suggested the existence of adrenoceptor subtypes. Recently three subtypes (α1a, α1b, and α1d) were cloned. Using probes for these subtypes, we demonstrated their expression in the tissues of ten cases of benign prostatic hypertrophy, usingin situ hybridization. To determine the ratio between these subtypes, an RNase protection assay was also performed in three cases. Expression of the α1a and α1d adrenoceptors was diffuse in the smooth muscles of the interstitium, but was absent in glandular epithelial cells. On the contrary, the α1b adrenoceptor was hardly detectable. The RNase protection assay confirmed the absence of the α1b adrenoceptor, the ratio of α1a and α1d being 4∶1. These results supported the idea that the differences in prostatic contractile response to several adrenergic drugs are based on the affinities of these drugs for the different subtypes.