Influence of vasectomy on the volume of the non-hyperplastic prostate in men

Response of the adult prostate to prepubertal and postpubertal obstruction of the vas deferens in the rat

OBJECTIVES

To determine whether obstruction of the vas deferens alters several general measures of prostate development during puberty and during prostate maintenance in the adult rat. Previous reports have suggested the possibility that vasectomy results in alterations of prostate function in experimental animals and humans.

METHODS

Adult rats and 10-day-old rats were subjected to bilateral sham operations or bilateral vasectomy, and the prostates were extirpated either 14 or 60 days later. The total prostate weight and dorsolateral and ventral lobe total protein per milligram tissue, DNA per milligram tissue, and DNA per milligram protein were determined. Dorsolateral and ventral prostate lobe sections from each group were also stained with hematoxylin-eosin and subjected to histologic examination.

RESULTS

The histologic features of the adult rat prostate were not qualitatively altered by vasectomy whether it occurred before puberty or in adult animals with mature prostates. Furthermore, vasectomy did not significantly alter the prostate weight or the protein or DNA content of either the dorsolateral or ventral lobes of the prostate compared with the sham-operated animals of either age.

CONCLUSIONS

Vas deferens obstruction does not significantly alter the parameters associated with the development or maintenance of the adult rat prostate measured in this study.

Androgen metabolism in the different lobes of the prostate gland of intact, gonadectomized or hypophysectomized rats with or without androgen substitution

The effect of gonadectomy or hypophysectomy and the effect of substitution with testosterone, upon the reductive and oxidative metabolic transformations of testosterone, 4-androstene-3,17-dione, 17 beta-hydroxy-5 alpha-androstane-3-one, 5 alpha-androstane-3 alpha, 17 beta-diol and 5 alpha-androstane-3 beta, 17 beta-diol using NAD(H) and NADP(H) as added cofactors were examined in homogenates from the ventral (VP), lateral (LP) and dorsal prostate (DP), and coagulating gland (CG) of adult Wistar rats. The fall in serum testosterone induced by gonadectomy or hypophysectomy led to reduced activity of 5 alpha-reductase, NADP(H)-dependent 3 alpha-hydroxysteroid oxidoreductase (3 alpha-HSOR), NAD-dependent 3 alpha-HSOR, 3 beta-HSOR and 17 beta-HSOR, indicating that these enzymes are androgen dependent. The NADP dependent oxidation of 5 alpha-androstane-3 alpha, 17 beta-diol in LP increased upon hypophysectomy and gonadectomy. Testosterone substitution of gonadectomized or hypophysectomized rats generally maintained enzymatic activity at the level of the control group, except for the 5 alpha-reductase activity which fell in spite of this treatment. Hypophysectomy or gonadectomy had different effects on the activity of several androgen metabolizing enzymes; 5 alpha-reductase activity in DP and CG, NAD(H) dependent 3 alpha-HSOR in VP and NADPH dependent 3 beta-HSOR activity in LP, DP and CG. There were marked differences between the rat prostatic lobes, both concerning the activity of the androgen metabolizing enzymes and the responses to the different treatment modalities.

The long-term influence of vasectomy on prostatic volume and morphology in man

During the past two decades several papers have described the changes in prostatic secretory capacity following vasectomy. Based upon results indicating a reduction of secretory function, it was suggested that even prostatic size and the incidence of benign prostatic hyperplasia (BPH) might be altered after the operation. In this study, which included 56 males who had been vasectomized 8 years previously and 56 age-matched control persons, transrectal ultrasonic scanning of the prostate was used for exact measurements of the prostatic volume and for the investigation of intraprostatic echo pattern. The total prostatic volume, the volume of the periurethral gland, and the volume of the peripheral zone were not influenced by the vasectomy; nor was the growth rate of these zones affected. In the vasectomy group, the frequency of adenomatous prostates was 19.6%, whereas 30.3% of prostates in the control group had ultrasonic signs of BPH. However, this is not a statistically significant difference. Subdividing the material according to age did not reveal altered BPH frequency in any age group when vasectomized and controls were compared.