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 (E₂), selective E₂ 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), E₂, 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 E₂, 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; E₂ and SERMs may worsen voiding patterns.