Functional and anatomical effects of hormonally induced experimental prostate growth: A urodynamic model of benign prostatic hyperplasia (BPH) in the beagle

BACKGROUND. Benign prostatic hypertrophy (BPH) produces a variety of changes in the urodynamic pattern of micturition and is usually associated with high detrusor voiding pressureandpoorurineflow-rate.Inmostpreviousexperimentalmodels,designedtosimulate this condition, some degree of obstruction is immediately imposed by the technique employed to produce urethral occlusion. Consequently these models cannot reproduce the gradual onset of obstruction. In the present study a canine prostatic enlargement model, using 5adihydrotestosterone(DHT) þ17b-estradiol(E)wasadaptedinordertoproduceamoregradual onset of partial obstruction and impaired voiding. MATERIALS AND METHODS. Hormonally induced prostatic enlargement was produced using seven beagles, given DHT 75 mg/day together with E 0.75 mg/day for 28 days via an implantable pump. The functional effects of DHT þE treatment on micturition pressure/flow were measured in the conscious animal. Identical measurements were also made using a separateoldergroupoffivebeagleswithsymptomsofBPH.Inadditionsevenbeaglessimilarly instrumented were used as controls. RESULTS. Pressure/flow studies show that DHT þE produced obstructive micturition, characterized by a significantly increased micturition detrusor pressure, from 33.3 � 10.5 to 50.8 � 10.7 cmH2O and significantly decreased low urine flow-rate from 8.6 � 2.1 to 6.9 � 0.9 ml/sec. Associated with the obstructive micturition, this treatment increased wet prostate weight from 11.9 � 2.5 to 31.6 � 10.0 g. Prostate volume of the BPH beagles was 29.3 � 8.9 g. MorphologicstudiesshowthatDHT þEproducedepithelialhyperplasiaextendingfocallyinto the lumen. CONCLUSIONS. Hormonally induced prostate growth produced bladder obstruction, in terms of pressure/flow characteristics, that are analogous to BPH. It is suggested that this type of hormonal treatment can be used to create a model for the study of the effects of controlled increased in prostate growth and the development of BPH on micturition. Prostate 58: 156–163, 2004. # 2003 Wiley-Liss, Inc.