Autoradiographic localization of alpha 1-adrenoceptors in human prostate: special reference to zonal difference

Using autoradiography, localization of alpha 1-adrenoceptor in human prostate was examined with particular reference to zonal difference. Prostatic tissues were obtained from total cystoprostatectomy specimens of six male bladder tumor patients. Peripheral zone (PZ), central zone (CZ) and preprostatic region which contained preprostatic sphincter and periurethral gland were dissected from the tissues. [125I]-HEAT was used as radioligand for autoradiography. Autoradiographic distribution of alpha 1-adrenoceptor was quantitated by grain counting using a light microscope equipped with a micrometer. Specific binding was demonstrated predominantly in fibromuscular stroma of PZ, fibromuscular stroma of CZ and preprostatic sphincter. No specific binding was demonstrated in glandular epithelium of PZ and periurethral gland. Glandular epithelium of CZ showed a few specific bindings. Among fibromuscular portion, specific bindings in both CZ and preprostatic sphincter were significantly higher than in PZ. Specific binding in glandular epithelium of CZ was significantly less than in fibromuscular stroma of PZ. These results show that the human prostate has a zonal difference in the distribution of alpha 1-adrenoceptors, probably reflecting some functional difference in these regions.