Detection of α1-adrenoceptor subtypes in human hypertrophied prostate byin situhybridizationsubtypes in human hypertrophied prostate byin situhybridization

Adrenergic stimulation induces contraction of hypertrophied prostatic tissue via the α1adrenoceptor, 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 situhybridization. To determine the ratio between these subtypes, an RNase protection assay was also performed in three cases. Expression of the α1aand α1dadrenoceptors was diffuse in the smooth muscles of the interstitium, but was absent in glandular epithelial cells. On the contrary, the α1badrenoceptor was hardly detectable. The RNase protection assay confirmed the absence of the α1badrenoceptor, the ratio of α1aand α1dbeing 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.