Angiotensin AT(4) receptors in the normal human prostate and benign prostatic hyperplasia

The cellular localisation and expression of angiotensin AT(4) receptors was examined in the normal human prostate and benign prostatic hyperplasia (BP H) by quantitative in vitro autoradiography using [I-125]-Ang IV. In the no rmal human prostate., AT(4) receptors were localised to the glandular epith elium. Interestingly, specific AT(4) receptor binding was significantly red uced in BPH compared to the normal prostate. as quantitated macroscopically (normal: 5038 +/- 476 dpm/mm(2), n = 6 vs BPH: 2701 +/- 176 dpm/mm(2), n = 6, P < 0.001) and microscopically (normal: 7.28 +/- 0.36 grains/mm(2), n = 6 vs BPH: 2.50 +/- 0.47 grains/mm(2). n = 6, P < 0.001). The findings of t he present study demonstrate the presence of AT(4) receptors in the human p rostate, being localised. to the glandular epithelium, which suggest that t he Ang IV/AT(4) system may play a role in the regulation of ionic transport and glandular secretion in the human prostate. The observation that AT(4) receptors appear reduced in BPH suggests that the AT(4) receptor may underg o agonist-induced receptor internalisation, possibly due to increased local tissue levels of Ang IV in BPH. (C) 2001 Elsevier Science Ireland Ltd. All rights reserved.