The potential of hormones and selective oestrogen receptor modulators in preventing voiding dysfunction in rats

Effects of ospemifene on the female reproductive and urinary tracts: translation from preclinical models into clinical evidence

Objective

Treatment of menopausal symptoms by compounds with tissue-selective estrogen agonist/antagonist effects, often called selective estrogen receptor modulators, has been researched as an alternative to the use of estrogen therapy. These structurally diverse molecules elicit tissue-dependent responses in hormone-responsive tissues and organs, exhibiting variations in estrogenic activity in preclinical models of postmenopausal reproductive tissues that may improve postmenopausal women’s health (eg, prevention and treatment of breast cancer, osteoporosis, and vulvar and vaginal atrophy).

Methods

This literature review investigates whether preclinical data predicted the clinical effects of ospemifene on female reproductive and urinary tract tissues and compares these findings with the specific vaginal effects of other estrogen receptor agonists/antagonists (tamoxifen, raloxifene, and bazedoxifene) in preclinical and clinical studies. Lasofoxifene, although not currently available, is included because of its unique effects on vaginal tissue.

Results

The response of endometrial and vaginal tissues to estrogen receptor agonists/antagonists can be differentiated using transvaginal ultrasound, endometrial histopathology, cytologic examination of vaginal smears, assessment of physical changes in the vagina, and relief of symptoms associated with vulvar and vaginal atrophy (such as dyspareunia).

Conclusions

Available evidence indicates that ospemifene has unique effects on tissue, leading to a favorable long-term profile for the relief of vulvar and vaginal atrophy compared with other estrogen receptor agonists/antagonists (eg, tamoxifen, raloxifene, and bazedoxifene) with no short-term concerns about endometrial safety (based on endometrial hyperplasia, carcinoma, endometrial spotting, and endometrial bleeding).

Estrogen attenuates TGF-β1 induced elastogenesis in rat urethral smooth muscle cells by inhibiting Smad response elements

PURPOSE

We investigated the effect and mechanism of estrogen on elastogenesis in urethral smooth muscle cells in vitro.

MATERIALS AND METHODS

Urethral smooth muscle cells were isolated from normal adult female rats. For elastogenesis assay cells were treated with TGF-β1, the potent TGF-β1 receptor inhibitor SB431542 and estrogen for 2 weeks. Real-time polymerase chain reaction was performed to assay gene expression during this process. Activity of the TGF-β1 responsive elements CAGA(12)-Luc and GCCG(12)-Luc were also assayed. Estrogen receptor and Smad2/3 interaction was evaluated by immunoprecipitation and Western blot.

RESULTS

TGF-β1 induced elastogenesis in rat urethral smooth muscle cells. This effect was partially blocked by estrogen and completely abrogated by SB431542. SB431542 completely inhibited activation of the Smad2/3 response element CAGA(12)-Luc and estrogen significantly inhibited activation. The Smad1/4 response element GCCG(12)-Luc was not affected by SB431542 treatment but estrogen partially inhibited the activation of GCCG(12)-Luc induced by TGF-β1. Estrogen receptor bound to Smad 2 and 3 in vitro.

CONCLUSIONS

Estrogen attenuated TGF-β1 induced elastogenesis via binding of its activated receptor to Smad2/3 to inhibit the TGF-β1 response element in rat urethral smooth muscle cells.

Pharmacological approach to overactive bladder and urge urinary incontinence in women: an overview

Besides life-style changes, electrical stimulation or surgery, pharmacological treatment is becoming the first-choice approach in women suffering from lower urinary tract symptoms (LUTS), including urge urinary incontinence (UUI) and overactive bladder (OAB). Several drugs for the treatment of bladder storage and voiding disorders are currently available and, in the near future, novel compounds with higher specificity for the lower urinary tract receptors will be accessible. This will bring optimization of therapy, reducing side effects and increasing compliance, especially in patients with comorbidities and in women. The purpose of this paper is to give an overview on the pharmacotherapy of two common inter-correlated urological conditions, UUI and OAB. The study was conducted by analyzing and comparing the data of the recent international literature on this topic. Advances in the discovery of pharmacological options have dramatically improved the quality of life of patients affected by incontinence, but further studies are needed to increase the effectiveness and safety of the therapies used in this field.

Effects of prolonged vaginal distension and β-aminopropionitrile on urinary continence and urethral structure

OBJECTIVE

To investigate the effects of prolonged vaginal distension and β-aminopropionitrile (BAPN) on the urinary patterns and urethral structure in female virgin rats.

METHODS

A total of 21 female virgin rats were randomly divided into 3 groups of 7 rats each. The control group received no intervention; the vaginal distension (VD) group was treated with prolonged VD by balloon inflation; and the VD plus BAPN group was treated with VD plus intraperitoneal injection of 150 mg/kg of BAPN every 3 days. Three weeks later, all the rats underwent conscious cystometric analysis and were then killed for histologic analysis of the urethra.

RESULTS

Conscious cystometry identified 0, 3, and 5 rats in the control, VD, and VD plus BAPN groups with an abnormal voiding pattern, respectively. The urethral collagen content was significantly lower in the VD and VD plus BAPN rats compared with the control rats. The urethral elastic fibers were disorganized and shorter in the VD and VD plus BAPN rats and were fragmented and lacking the intermuscle connections in the VD plus BAPN rats. The urethral striated muscle fibers were shorter and more widely spaced in the VD and VD plus BAPN rats than in the control rats. Additionally, those in the VD plus BAPN group exhibited an abnormal wavy shape suggestive of a lack of architectural support.

CONCLUSION

Prolonged vaginal distension caused urodynamic changes and histologic abnormalities in the urethra, including reduced collagen content, fragmented elastic fibers, and sparsely arranged and shortened striated muscle fibers. BAPN appears to interfere with the restoration of collagen and elastic fibers.

Effects of estrogen, raloxifene, and levormeloxifene on the expression of Rho-kinase signaling molecules in urethral smooth muscle cells

OBJECTIVES

To investigate the effects of estrogen, raloxifene, and levormeloxifene on the expression of Rho-kinase signaling molecules in urethral smooth muscle cells (USMCs).

METHODS

USMCs were isolated from female rats. Expression of calponin and estrogen receptors α (ERα) was detected by immunofluorescence staining. Cells were treated with estrogen, raloxifene, or levormeloxifene at 0, 1, 10, and 100 nmol/L for 48 h and then processed for Western blotting with antibodies against RhoA, Rho kinase I and II (Rock-I and Rock-II), myosin light chain (MLC), phosphorylated MLC, and β-actin. Protein expression was quantitated by densitometry, followed by statistical analysis with β-actin as control.

RESULTS

USMCs expressed calponin and ERα. Treatment of USMCs with estrogen, raloxifene or levormeloxifene resulted in decreased expression of RhoA, Rock-I, Rock-II, and p-MLC in a dosage-dependent manner.

CONCLUSIONS

Estrogen, raloxifene, and levormeloxifene may affect urinary continence by inhibiting the expression of Rho-kinase signaling molecules.

The effect of long-term hormonal treatment on voiding patterns during filling cystometry and on urethral histology in a postpartum, ovariectomized female rat

OBJECTIVE

To study whether long-term treatment with oestrogen (E(2) ), selective E(2) receptor modulators (SERMs), or growth hormone (GH) can prevent the development of abnormal voiding patterns during filling cystometry (CMG) in a postpartum, ovariectomized (Ovx) female rat.

MATERIALS AND METHODS

Immediately after spontaneous delivery, 60 primiparous Sprague-Dawley rats were randomly divided into six equal groups. One group served as uninjured sham controls and five groups underwent intravaginal balloon dilatation. On day seven, previously dilated rats underwent bilateral Ovx and implantation of a subcutaneous hormone-delivery pump. The five treatment groups received normal saline (control), E(2) , raloxifene, levormeloxifene, or GH for 7 weeks. Conscious CMG was performed 7 weeks after Ovx. Urethral sphincter tissue was harvested for elastin immunohistochemistry and real-time polymerase chain reaction of α(1A) -adrenoceptor mRNA.

RESULTS

No abnormal voiding patterns were detected in the group treated with GH. The E(2) , raloxifene and levormeloxifene groups had greater detrusor overactivity and urethral relaxation incontinence than control rats. The raloxifene group had a significantly lower baseline bladder pressure and opening pressure. GH-treated rats had higher elastin content in the urethra. Urethral α(1A) -adrenoceptor mRNA concentration was significantly lower in the SERM-treated rats compared with controls.

CONCLUSIONS

GH prevents the development of abnormal voiding patterns during filling CMG in a rat model of parturition-induced incontinence; E(2) and SERMs may worsen voiding patterns.

Effects of birth trauma and estrogen on urethral elastic fibers and elastin expression

OBJECTIVES

To investigate the effects of birth trauma and estrogen on urethral elastic fibers and elastin expression.

METHODS

Pregnant rats were subjected to sham operation (Delivery-only), DVDO (delivery, vaginal distension and ovariectomy), or DVDO + E₂ (estrogen). At 2, 4, 8, or 12 weeks, their urethras were harvested for elastic fiber staining and reverse transcription-polymerase chain reaction analysis. Urethral cells were treated with transforming growth factor- β1 (TGFβ1) and/or estrogen and analyzed for elastin mRNA expression. Urethral cells were also examined for the activities of Smad1- and Smad3/4-responsive elements in response to TGFβ1 and estrogen.

RESULTS

At 8 weeks post-treatment, the urethras of DVDO rats had fewer and shorter elastic fibers when compared with Delivery-only rats, and those of DVDO + E₂ rats had fewer and shorter elastic fibers when compared with DVDO rats. Elastin mRNA was expressed at low levels in Delivery-only rats and at increasingly higher levels in DVDO rats at 2, 4, and 8 weeks but at sharply lower levels in DVDO + E₂ rats when compared with DVDO rats at 8 weeks. Urethral cells expressed increasingly higher levels of elastin mRNA in response to increasing concentrations of TGFβ1 up to 1 ng/mL. At this TGFβ1 concentration, urethral cells expressed significantly lower levels of elastin mRNA when treated with estrogen before or after TGFβ1 treatment. Both Smad1- and Smad3/4-responsive elements were activated by TGFβ1 and such activation was suppressed by estrogen.

CONCLUSIONS

Birth trauma appears to activate urethral elastin expression via TGFβ1 signaling. Estrogen interferes with this signaling, resulting in improper assembly of elastic fibers.

Treatment of stress urinary incontinence with adipose tissue-derived stem cells

BACKGROUND AIMS

Effective treatment for stress urinary incontinence (SUI) is lacking. This study investigated whether transplantation of adipose tissue-derived stem cells (ADSC) can treat SUI in a rat model.

METHODS

Rats were induced to develop SUI by postpartum vaginal balloon dilation and bilateral ovariectomy. ADSC were isolated from the peri-ovary fat, examined for stem cell properties, and labeled with thymidine analog BrdU or EdU. Ten rats received urethral injection of saline as a control. Twelve rats received urethral injection of EdU-labeled ADSC and six rats received intravenous injection of BrdU-labeled ADSC through the tail vein. Four weeks later, urinary voiding function was assessed by conscious cystometry. The rats were then killed and their urethras harvested for tracking of ADSC and quantification of elastin, collagen and smooth muscle contents.

RESULTS

Cystometric analysis showed that eight out 10 rats in the control group had abnormal voiding, whereas four of 12 (33.3%) and two of six (33.3%) rats in the urethra-ADSC and tail vein-ADSC groups, respectively, had abnormal voiding. Histologic analysis showed that the ADSC-treated groups had significantly higher elastin content than the control group and, within the ADSC-treated groups, rats with normal voiding pattern also had significantly higher elastin content than rats with voiding dysfunction. ADSC-treated normal-voiding rats had significantly higher smooth muscle content than control or ADSC-treated rats with voiding dysfunction.

CONCLUSIONS

Transplantation of ADSC via urethral or intravenous injection is effective in the treatment and/or prevention of SUI in a pre-clinical setting.

Effect of estrogen and progesterone on urodynamics in the conscious rat

OBJECTIVES

To examine the effects of estrogen and/or progesterone on the cystometric profiles obtained using continuous-filling cystometry in the conscious Sprague-Dawley rat.

METHODS

Sprague-Dawley rats underwent ovariectomy (OVX) and were compared with controls by conscious continuous-filling cystometry. The effect of estrogen (10 microg/kg/d for 14 days) and/or progesterone (10 mg/kg/d for 14 days) replacement on OVX urodynamics was examined (n = 7-8/group).

RESULTS

OVX rats demonstrated reduced micturition intervals and voided volumes compared with controls. These effects of OVX were reversed by estrogen replacement, but not by progesterone replacement. When combined with estrogen, progesterone functioned to partially antagonize the effects of estrogen in OVX rats.

CONCLUSIONS

Estrogen enhances bladder capacity in the OVX rat and therefore is a likely contributor to the larger bladder capacity in the female compared with the male rat. Consistent with its established role in reproductive physiology, progesterone antagonizes the beneficial effects of estrogen on OVX rat urodynamics.