Effect of estrogen treatment on the peroxidase activity and estrogen receptors in the female rabbit urogenital tissues

Characterization of Myeloperoxidase in the Healthy Equine Endometrium

Myeloperoxidase (MPO), as a marker of neutrophil activation, has been associated with equine endometritis. However, in absence of inflammation, MPO is constantly detected in the uterine lumen of estrous mares. The aim of this study was to characterize MPO in the uterus of mares under physiological conditions as a first step to better understand the role of this enzyme in equine reproduction. Total and active MPO concentrations were determined, by ELISA and SIEFED assay, respectively, in low-volume lavages from mares in estrus (n = 26), diestrus (n = 18) and anestrus (n = 8) in absence of endometritis. Immunohistochemical analysis was performed on 21 endometrial biopsies randomly selected: estrus (n = 11), diestrus (n = 6) and anestrus (n = 4). MPO, although mostly enzymatically inactive, was present in highly variable concentrations in uterine lavages in all studied phases, with elevated concentrations in estrus and anestrus, while in diestrus, concentrations were much lower. Intracytoplasmic immunoexpression of MPO was detected in the endometrial epithelial cells, neutrophils and glandular secretions. Maximal expression was observed during estrus in mid and basal glands with a predominant intracytoplasmic apical reinforcement. In diestrus, immunopositive glands were sporadic. In anestrus, only the luminal epithelium showed residual MPO immunostaining. These results confirm a constant presence of MPO in the uterine lumen of mares in absence of inflammation, probably as part of the uterine mucosal immune system, and suggest that endometrial cells are a source of uterine MPO under physiological cyclic conditions.

[Role of estrogens in lower urinary tract physiology and physiopathology]

GOAL

The aim was to review the literature on estrogens and lower urinary tract.

MATERIAL

A review of literature through the PubMed library until December 31, 2012 was carried out using the following keywords: lower urinary tract, bladder, urethra, nervous central system, innervation, female, women, estrogen, estradiol, urogenital atrophy, urinary incontinence, overactive bladder, urinary tract infection.

RESULTS

On the bladder, estrogens are involved in the trophicity, vascularisation, alpha-adrenergic, cholinergic and muscarinic receptor density, detrusor contractility and inflammation. On the urethra, they impact vascularisation, contractility, urethral pulse and tone, anatomical and functional length. On the neurological control, they act on capsaicin-sensitive afferent fibres, neurological regeneration, nerve growth factor expression and viscerovisceral sensitisation.

CONCLUSION

Estrogens play a major role on the lower urinary tract physiology and physiopathology both on the urethra and the bladder.

Acquired urinary incontinence in the bitch: update and perspectives from human medicine. Part 2: The urethral component, pathophysiology and medical treatment

Various pathologies can affect the bladder and/or urethral contractility causing signs of urinary incontinence. In this second part of a three-part review, the pathophysiology of impaired urethral contractility (including urethral hyper- and hypotonicity) in the bitch and in women is discussed. Urethral sphincter mechanism incompetence (USMI) is the most common form of acquired urinary incontinence in bitches and is characterized by a decreased urethral tone. The pathophysiology and current recommended medical treatment options for USMI and cases of modified urethral tonicity due to a neurological disorder or functional outlet obstruction are discussed. Treatment options in human medicine in cases of impaired urethral contractility are described.

Urodynamic and morphologic changes in the lower portion of the urogenital tract after administration of estriol alone and in combination with phenylpropanolamine in sexually intact and spayed female dogs

OBJECTIVE

To compare the urodynamic and morphologic effects of the administration of estriol alone and in combination with phenylpropanolamine on the lower portion of the urogenital tract in female dogs.

ANIMALS

3 sexually intact and 3 spayed female Beagles without urinary incontinence.

PROCEDURE

Dogs received estriol (2 mg, PO) once daily for 7 days followed by estriol (2 mg, PO) and phenylpropanolamine (1.5 mg/kg, PO) once daily for 7 days. Urethral pressure profilometry, diuresis cystometry, and vaginourethrography were performed before treatment (day 0) and at days 7 and 14. The maximum urethral pressure (MUP) and closure pressure (MUCP), urethral functional and anatomic profile lengths, integrated pressure (IP), plateau, distance before MUP, maximum meatus pressure, threshold pressure, threshold volume, compliance, urethral length, and vaginal length and width were measured.

RESULTS

Before treatment, no urodynamic differences were observed between the 2 groups; however, vaginal length and width were significantly shorter in spayed dogs. Compared with day 0 values, estriol treatment significantly increased MUP, MUCP, and IP values at day 7, but at day 14, this effect decreased despite phenylpropanolamine administration. No morphologic changes from baseline were detected after either treatment in any dog.

CONCLUSIONS AND CLINICAL RELEVANCE

Data suggest that estriol mainly acts on the urethral sphincter mechanism by increasing urethral resistance in sexually intact and spayed female dogs without urinary incontinence. Administration of estriol and phenylpropanolamine did not increase the urethral resistance more than estriol alone. The urodynamic effects of estriol in female dogs with urinary incontinence remain to be elucidated.

The effects of delayed hormone replacement therapy on estrogen receptors of the cynomolgus monkey bladder and vagina

The aim of this study was to determine cytosolic estrogen receptor content of the cynomolgus monkey bladder and vagina after hormone replacement therapy. Animals maintained without hormone therapy for 2 years after surgical menopause were randomized to receive either no hormones (OVX), conjugated equine estrogens (CEE), or estrogen/medroxyprogesterone acetate (CEE + MPA) treatment for 30 months. Estrogen receptor content of bladder and vagina cytosolic extracts was determined using a commercial enzyme-linked immunosorbent assay. Estrogen receptors were uniformly present, although the vaginal concentration was 100-fold greater than in the bladder. Estrogen and combination therapy significantly decreased cytosolic receptor content in both sites compared with controls. The cynomolgus urogenital tract remains estrogen sensitive 2 years after surgical menopause. Prolonged exposure to estrogens decreases cytosolic estrogen receptor content in a manner similar to that described for short-term estrogen therapy. These results suggest that the effects of hormone replacement on the urinary tract can be identified even if initiated years after menopause.

Downregulation by estrogen of nitric oxide synthase activity in the female rabbit lower urinary tract

OBJECTIVES

Because female urinary tract tissues are considered to be targets for estrogen, and because nitric oxide (NO) is known to participate in the nerve-induced relaxation in the lower urinary tract, the effect of estrogen on nitric oxide synthase (NOS) in the upper and lower urinary tracts was examined.

METHODS

Ovariectomized rabbits were treated with polyestradiol phosphate, and NOS in both cytosolic and particulate fractions from kidney, urinary pelvis, ureter, urinary bladder, trigonum, and urethra was characterized. NOS activity was measured by the formation of [14C]-L-citrulline from [14C]-L-arginine.

RESULTS

NOS was considerably higher in cytosolic than in particulate fractions from all urinary tracts, and activity in both fractions was highly calcium dependent. NOS activity was much lower (fourfold to eightfold) in the kidney and pelvis than in the ureter. Estrogen treatment caused no change in NOS in either fraction from upper urinary tract tissues. In the lower urinary tract, NOS was slightly higher in the bladder and trigonum than in the urethra, and activities were comparable to NOS in the ureter. In contrast to the upper urinary tract, estrogen treatment led to a significant reduction of cytosolic NOS in the bladder, trigonum, and urethra. Estrogen, however, caused no significant change in the particulate NOS.

CONCLUSIONS

Downregulation by estrogen in cytosolic NOS in the tissue of the lower urinary tract is consistent with the presence of estrogen receptors and suggests a physiologic significance.

Effects of pregnancy on urethral and bladder neck function

Pregnancy and menopause induce morphologic as well as functional changes in the female urethra. Symptoms of bladder irritation (frequency, urgency) and incontinence are frequent findings in these conditions and are considered to be due to alterations in the distribution of autonomic receptors induced by the changes in the hormonal milieu. In the present study, the functional responses to field stimulation (FS) and autonomic agonists of the bladder neck and urethra of pregnant, and virgin New Zealand White rabbits were compared using isolated muscle strips. Passive length-tension studies demonstrated a significantly greater compliance of strips (bladder neck and urethra) from pregnant rabbits than from virgin rabbits. FS elicited frequency dependent contractile responses in all strips. Phentolamine was significantly more effective at inhibiting the field stimulated contractile response of urethral strips from pregnant than from virgin rabbits. Atropine was significantly more effective at inhibiting the response to FS of strips isolated from bladder necks of virgin rabbits than in strips isolated from pregnant rabbits. Atropine was significantly less effective at inhibiting the response to FS of strips isolated from urethras of pregnant rabbits than of strips from virgin rabbits. Strips of bladder neck and urethra isolated from virgin rabbits responded with significantly greater contraction to phenylephrine than strips isolated from pregnant rabbits. The magnitude of field stimulated relaxation was significantly greater in urethral strips than in bladder neck strips, and also greater in urethral strips isolated from virgin rabbits than in strips isolated from pregnant rabbits. In conclusion, pregnancy induces profound hormonal changes which, in turn, result in the alteration of the compliance and functional responses of the bladder neck and urethra to various forms of autonomic stimulation and relaxation.