Differential endocrine regulation of genes enriched in initial segment and distal caput of the mouse epididymis as revealed by genome-wide expression profiling.

We have performed genome-wide expression profiling of endocrine regulation of genes expressed in the mouse initial segment (IS) and distal caput of the epididymis by using Affymetrix microarrays. The data revealed that of the 15 020 genes expressed in the epididymis, 35% were enriched in one of the two regions studied, indicating that differential functions can be attributed to the IS and the more distal caput regions. The data, furthermore, showed that 27% of the genes expressed in the IS and/or distal caput epididymidis are under the regulation of testicular factors present in the duct fluid, while bloodborne androgens can regulate for 14% of them. This is in line with the high testis dependency of epididymal physiology. We then focused on genes with moderate or strong expression, showing strict segment enrichment and strong dependency on testicular factors. Analyses of the 59 genes, including upregulated and downregulated genes, fulfilling the criteria indicated that the expression of 18 (17 downregulated genes; 1 upregulated gene) of 19 gonadectomy-responsive genes enriched in the IS was not maintained by the androgen treatment, whereas the expression of all six downregulated genes enriched in the distal caput and the majority of those with no strict segment enrichment of expression (28 of 34; consisting of 23 downregulated and 5 upregulated genes) were maintained by androgens. Hence, it is evident that testicular factors other than androgens are important for the expression of IS-enriched genes, whereas the expression of distal caput-enriched genes is typically regulated by androgens. Identical data were obtained by independent clustering analyses performed for the expression data of 3626 epididymal genes. Several novel genes with putative involvement in epididymal sperm maturation, such as a disintegrin and metallopeptidase domain 28 (Adam28) and a solute carrier organic anion transporter family, member 4C1 (Slco4c1), were identified, indicating that this approach is successful for identifying novel epididymal genes.

Division of the male rat rhabdosphincter into structurally and functionally differentiated parts.

In order to understand the structure-function relationship in the male rat rhabdosphincter, the 3D structure of the striated muscle and associated dense connective tissue was reconstructed from representative serial sections cut from the proximal urethra harboring the muscle. The 3D structure was correlated with electromyography (EMG) of the rhabdosphincter, urodynamic parameters (bladder pressure and flow rate), and longitudinal contraction force of the proximal urethra. The muscular component of the rhabdosphincter consisted of a homogeneous population of the fast-twitch-type fibers. In the cranial part, striated muscle formed a complete ring encircling the urethra, deferent ducts, and ducts from seminal vesicles and prostatic lobes. Toward the middle part, the amount of densely packed connective tissue lacking type III collagen increased anteriorly and posteriorly and penetrated the muscular ring that became divided first posteriorly and then anteriorly into two symmetrical halves. In the caudal part, a thin midsagittal dense connective tissue septum remained posteriorly. EMG recordings suggested that the rhabdosphincter muscle was functionally divided into two parts. Unlike the cranial and middle parts, the caudal part did not show the first depolarization peak. It appears that rapid oscillatory oblique-to-circular muscular contractions proceeding in craniocaudal direction in the cranial and middle part draw the anterior wall supported by arch-like dense connective tissue closer to the posterior wall supported by a more rigid rhomboidal raphe. Longitudinal contractions of the urethra are possibly evoked from the proximal and caudal parts of rhabdosphincter. These could lead to simultaneous increase in urethral pressure ensuring rapid urine flow rate. The caudal part could augment the opening of urethral lumen during oscillatory voiding.

Developmental, estrogen induced infravesical obstruction is reversible in adult male rodents.

PURPOSE: We treat neonatally estrogenized rats and aromatase over expressing AROM+ male mice with infravesical obstruction using the specific aromatase inhibitors finrozole and letrozole, and analyzed whether developmentally induced alterations in urodynamics and rhabdosphincter are reversible in adulthood. MATERIALS AND METHODS: Adult estrogenized rats and AROM+ mice were treated with aromatase inhibitors for 6 weeks. Maximal and mean bladder pressure, the urinary flow rates and electromyography activity were recorded from the proximal rhabdosphincter. In addition, proximal rhabdosphincter thickness in the AROM+ mouse was measured and correlated with seminal vesicle size and serum testosterone concentrations. RESULTS: Finrozole and/or letrozole treatment significantly increased the mean maximal flow rate plus or minus SD in AROM+ mice (4.7 +/- 2.0 versus 13.3 +/- 4.4 ml. per minute, p = 0.0004) and in estrogenized rats (18.4 +/- 6.18 versus 31.1 +/- 10.85 ml. per minute for finrozole p = 0.005) and 32.4 +/- 14.3 for letrozole, p = 0.005), while bladder pressure slightly decreased. The reappearance of transient repolarization, indicating urethral lumen opening, coincided with an increased flow rate on electromyography in the proximal rhabdosphincter in rats. Relative thickness of the proximal rhabdosphincter (p = 0.007), seminal vesicle size (p = 0.0002) and mean serum testosterone concentration (472.5 +/- 230.35 versus 3,065.6 +/- 1,994.67 pg./ml., p = 0.0002) were restored after finrozole treatment in AROM+ mice. CONCLUSIONS: Current findings indicate that alterations in urodynamics, seminal vesicle size, and rhabdosphincter size and function in developmentally estrogenized male rodents are reversible when treated with aromatase inhibitor.

Infravesical obstruction in aromatase over expressing transgenic male mice with increased ratio of serum estrogen-to-androgen concentration.

PURPOSE: The potential role of estrogen in the development of infravesical obstruction is still unresolved. Aromatase over expressing transgenic mice provide a novel instrument for investigating the consequences of prolonged systemic or local increases in endogenous estrogen concentrations. Two aromatase over expressing transgenic mouse strains with different prostatic phenotypes (reduced and normal size, respectively) were compared in urodynamic studies with each other and with the wild-type strain. MATERIALS AND METHODS: The bladder and urethra were exposed in adult male wild-type or transgenic mice. High frequency oscillations of intraluminal bladder pressure and flow rate from the distal urethra were simultaneously recorded with the mice under anesthesia. RESULTS: No changes were observed in voiding in MMTV-arom+ mice. These mice are known to have only slightly elevated estradiol concentrations in serum, suggesting a localized increase in estrogen production. In AROM+ mice the aromatase gene was detected in several organs, including the testis and bladder. These mice are known to have markedly increased estrogen and decreased serum androgen concentrations, and reduced prostate size. Compared with wild-type mice AROM+ mice showed higher mean maximal bladder pressure plus or minus standard deviation (33.1 +/- 6.4 versus 25.6 +/- 4.8 mm. Hg, p = 0.046) and decreased mean maximal flow rate (3.1 +/- 1.6 versus 17.7 +/- 5.4 ml. per minute, p <0.0001), consistent with the presence of the infravesical obstruction. Morphologically the proximal rhabdosphincter in AROM+ mice showed atrophy (relative mean thickness 0.005 +/- 0.015 versus 0.013 +/- 0.002 mm., p <0.0001). CONCLUSIONS: Activation of the aromatase gene during an earlier developmental stage under the ubiquitin C promoter and highly elevated serum estrogen concentrations may explain the differences in voiding and prostate size in the AROM+ mouse strain.