The effects of targeted deletion of the aromatase enzyme on prostatic contractile responses to noradrenaline in mice.
This investigation aimed to see whether a change in the oestrogen to androgen ratio alters prostate contractility. Isolated organ bath studies using prostates from aromatase knockout (ArKO) mice which were homozygous (ArKO-/-) and heterozygous (ArKO+/-) for the disrupted aromatase cyp19 gene and wild-type littermates (ArKO+/+) were conducted. The distribution of noradrenergic nerves was visualized using the sucrose-potassium phosphate-glyoxylic acid method. ArKO-/- mice had increased prostate weights compared with ArKO+/+ mice. Frequency-response curves to electrical field stimulation (EFS; 0.5 ms pulse duration, 60 V, 0.1-20 Hz) yielded frequency-dependent contractions, while noradrenaline (10 nM-1 mM) and tyramine (1 muM-1 mM) produced concentration-dependent contractions. Prazosin (0.3 muM) attenuated the responses induced by noradrenaline and EFS in all mice (P</=0.019, n=5-7), while cocaine (10 muM) attenuated the responses evoked by tyramine (P<0.001, n=6). There were no genotype differences in EFS- and noradrenaline-induced responses (P>/=0.506, n=10-13). Prostates from ArKO-/- and ArKO+/- mice were more sensitive to tyramine than prostates from ArKO+/+ mice (P<0.001, n=11-13). Dense adrenergic innervation of the prostate was similar in all mice. These results suggest that although the absence of aromatase increases prostatic growth, this translates only to a subtle and selective increase in contractility in mature mice.
Gray
Katherine T
KT
Prostate Research Co-operative, Victorian College of Pharmacy, Monash University, 381 Royal Parade, Parkville, Victoria 3052, Australia.
Short
Jennifer L
JL
Simpson
Evan R
ER
Ventura
Sabatino
S
D000320:Adrenergic Fibers / Q000378:metabolism; D000818:Animals; D001141:Aromatase / Q000172:deficiency* / Q000235:genetics; D002395:Catecholamines / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004558:Electric Stimulation; D006579:Heterozygote; D006720:Homozygote; D066298:In Vitro Techniques; D008297:Male; D051379:Mice; D018345:Mice, Knockout / Q000235:genetics; D009119:Muscle Contraction / Q000187:drug effects*; D009130:Muscle, Smooth / Q000187:drug effects / Q000502:physiology*; D009638:Norepinephrine / Q000008:administration & dosage / Q000494:pharmacology*; D009929:Organ Size; D009994:Osmolar Concentration; D011467:Prostate / Q000033:anatomy & histology / Q000187:drug effects* / Q000294:innervation / Q000502:physiology*; D013194:Staining and Labeling; D014439:Tyramine / Q000008:administration & dosage / Q000494:pharmacology
D002395:Catecholamines; D001141:Aromatase; D009638:Norepinephrine; D014439:Tyramine