Autoradiographic analysis of alpha-adrenoceptors and muscarinic cholinergic receptors in the hyperplastic human prostate.
Radioligand receptor binding and autoradiography were used to characterize, localize and compare alpha-1 and alpha-2 adrenoceptors and muscarinic cholinergic receptor populations in human benign prostatic hyperplastic tissue. The binding of selective alpha-1 and alpha-2 ligands, [3H]-prazosin and [3H]-UK 14,304, to homogenates of human central and peripheral prostate was saturable and of high affinity. Scatchard analysis produced an equilibrium dissociation constant (KD) of 0.51 +/- 0.10 nM for alpha-1 adrenoceptors, and 2.34 +/- 0.40 nM for alpha-2 adrenoceptors. The mean densities, Bmax, of alpha-1 and alpha-2 adrenoceptors identified in the human adenomatous prostate were 65.9 +/- 12.9 and 36.1 +/- 7.0 fmoles/mg. protein respectively. Receptor autoradiography was used to examine the distribution of muscarinic cholinergic receptors [( 3H]-QNB), alpha-1 adrenoceptors [( 3H]-prazosin]), and alpha-2 adrenoceptors [( 3H]-rauwolscine) on consecutive sections of benign hyperplastic prostatic tissue. Although both subtypes of adrenoceptor were seen in the stromal component of the hyperplastic prostate, there was a substantial predominance of alpha-1 adrenoceptors. A densitometric computer-assisted analysis was performed on the autoradiographic slides to determine the mean ratio of specific alpha-1: alpha-2 adrenoceptors in the stromal compartment of the hyperplastic tissue. The ratio, expressed as % grain occupancy/unit area, was 3.9 +/- 0.75, which is in agreement with a functional alpha-1 adrenoceptor predominance shown in previous studies. Although sparsely distributed in the stroma, a dense alpha-2 adrenoceptor population was seen in association with blood vessels, and in close proximity to the base of some of the [3H]-QNB-labelled prostatic glandular epithelial cells.(ABSTRACT TRUNCATED AT 250 WORDS)
James
S
S
Department of Anatomy and Developmental Biology, University College London, England.
Chapple
C R
CR
Phillips
M I
MI
Greengrass
P M
PM
Davey
M J
MJ
Turner-Warwick
R T
RT
Milroy
E J
EJ
Burnstock
G
G
D000368:Aged; D001345:Autoradiography; D006801:Humans; D008297:Male; D011467:Prostate / Q000032:analysis / Q000294:innervation; D011470:Prostatic Hyperplasia / Q000378:metabolism*; D011869:Radioligand Assay; D011942:Receptors, Adrenergic, alpha / Q000032:analysis*; D011976:Receptors, Muscarinic / Q000032:analysis*
D011942:Receptors, Adrenergic, alpha; D011976:Receptors, Muscarinic