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

Abstract

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.

Figure 1

Four channel conscious cystometry. The top tracing is vesical pressure; the second is abdominal pressure, the third is detrusor pressure, and the bottom tracing is the cumulative amount of voided urine. A: An example of normal tracing. B: An example of DO. C: An example of URI.

Figure 1

Four channel conscious cystometry. The top tracing is vesical pressure; the second is abdominal pressure, the third is detrusor pressure, and the bottom tracing is the cumulative amount of voided urine. A: An example of normal tracing. B: An example of DO. C: An example of URI.

Figure 1

Four channel conscious cystometry. The top tracing is vesical pressure; the second is abdominal pressure, the third is detrusor pressure, and the bottom tracing is the cumulative amount of voided urine. A: An example of normal tracing. B: An example of DO. C: An example of URI.

Figure 2

The percentage of rats with abnormal voiding patterns in various groups (10 animals per group). URI was seen in the estrogen, raloxifene and levormeloxifene groups, (Chi square, p-value = 0.017).

Figure 3

Representative photos of cross section of mid-urethra with trichome staining from the following groups: S-Sham; C-Control; E2-Estrogen; Ral-Raloxifene; Lev-Levormeloxifene; GH-growth hormone. After delivery, balloon dilation and ovariectomy, the matrix content in urethral wall was significantly decreased in all groups except the sham and the GH group.

Figure 4

Representative photos of cross-section of mid-urethra depicting collagen I and collagen III staining with Picrosirius red. Red color staining represents collagen I which is more abundant in urethral wall of the sham (S) and GH group as well as the control (C) group, though in lesser degree. Contrarily, more collagen III stainings (green color) are noted in control (C), estrogen (E2), raloxifene (Ral) and levormeloxifene (Lev) groups. Figures on the left are from 3 different rats (10x). Figures on the right are higher magnification (40x).

Figure 5

High power view of representative photos of cross-section of mid-urethra stained for elastin fibers (arrows). Elastin fibers appear well-organized and long in the sham (S) and growth hormone (d) group. In the control (b) and Estrogen (c) rats, the elastin fibers are fragmented and disorganized.

Figure 6

Alpha 1a receptor mRNA by real time PCR expressed as a ratio of alpha 1A to internal control (GADPH). The SERM groups had significantly (p=0.01) less expression of alpha 1a receptor mRNA in the urethral tissue compared to control.