Identification, quantification, and localization of mRNA for three distinct alpha₁ adrenergic receptor subtypes in human prostate

The dynamic component of bladder outlet obstruction caused by benign prostatic hyperplasia (BPH) is regulated by alpha₁ adrenergic receptors (α₁-AR) located in the prostatic stroma. Recently two α₁-AR subtypes (α(1A), α(1B)) have been identified in the human prostate by both functional and pharmacological assays. However, the presence of the α(1C) subtype has not been evaluated, presumably due to the lack of availability of selective ligands for this receptor subtype. We have used molecular techniques to investigate the mRNA expression of all three α₁-AR subtypes in the human prostate. RNA extracted from the prostate gland of 15 patients was used in ribonuclease protection assays to identify the expression of three α₁-AR subtype mRNAs. Quantitative solution hybridization assays further identify the predominant subtype of α₁-AR mRNA to be the α(1C), which represents approximately 70% of the total α₁-AR mRNA in the human prostate. Furthermore, in situ hybridization localizes the α(1C) AR mRNA predominantly to the stromal compartment. The identification of a predominant α₁-AR mRNA in human prostate identifies a potential need for subtype selective pharmaceutical agents. These agents could be very important clinically in the treatment of diseases such as BPH.