Subcutaneous B16 melanoma impairs intrinsic pressure generation and relaxation of the heart, which are not restored by short-term voluntary exercise in mice

The aim of this study was to investigate whether subcutaneous melanoma impairs intrinsic cardiac function and hypoxia tolerance in mice. Additionally it was investigated whether these changes could be prevented by voluntary running-wheel exercise. The role of different molecular pathways were also analysed. Male mice (C57Bl/6NCrl) were divided into unexercised tumor-free group, unexercised melanoma group and exercised melanoma group. Experiment lasted 2.7±0.1 weeks (determined by the tumor size) after which the heart function was measured in different oxygen levels ex vivo using Langendorff method. All the melanoma mice had lower pressure amplitude (50.3%), rate of pressure production (54.1%) and decline (52.5%) in hearts ex vivo as compared to tumor-free group. There were no functional differences between the two melanoma groups. All the groups had similar weight change, heart weights, cardiomyocyte sizes, levels of Ca²⁺-channels, energy metabolism enzyme activities, lipid peroxidation and reactive oxygen species in their cardiac tissue homogenates. However, all the melanoma mice had 7.4% lower superoxidase dismutase activity compared to the control animals, which might reduce the ability of the heart to react to changes in oxidative stress. The exercising melanoma group had 28.6% higher average heart capillary density compared to the unexercised melanoma group. Short-term wheel running did not affect the tumor growth. In conclusion, subcutaneous melanoma seems to impair intrinsic heart function even prior to cachexia and these functional alterations were not caused by any of the measured molecular markers. Short-term voluntary running-wheel exercise was insufficient to alleviate the intrinsic cardiac impairments caused by melanoma.

Characterization a model of prostatic diseases and obstructive voiding induced by sex hormone imbalance in the Wistar and Noble rats

Background

Chronic nonbacterial prostatitis associated with lower urinary tract symptoms (LUTS) is a prevalent condition in men. One potential pathophysiological factor is change in sex hormone, testosterone and estrogen, balance. Inflammation, cancer and obstructive voiding has been induced in the Noble rat strain by altering levels of sex hormones. We evaluated if imbalance of sex hormones could induce comparable diseases also in a less estrogen sensitive Wistar strain rats.

Methods

Subcutaneous testosterone (830 µg/day) and 17β-estradiol (83 µg/day) hormone pellets were used in male Wistar and Noble strain rats to induce prostatic diseases. The rats were followed for 13 and 18 weeks. Urodynamical measurements were performed at the end of the study under anesthesia. Prostates were collected for further histological analysis. A panel of cytokines were measured from collected serum samples.

Results

Noble rats exhibited stromal and glandular inflammation after 13 weeks that progressed into more severe forms after 18 weeks of hormonal treatment. CD68-positive macrophages were observed in the stromal areas and inside the inflamed acini. CD163-positive macrophages were present in the stromal compartment but absent inside inflammatory foci or prostate acini. Thirteen-week hormonal treatment in Noble rats induced obstructive voiding, which progressed to urinary retention after 18-weeks treatment. In the Wistar rats 18-week treatment was comparable to the 13-week-treated Noble rats judged by progression of prostatic inflammation, being also evident for obstructive voiding. Incidence of PIN-like lesions and carcinomas in the periurethal area in Noble rats were high (100%) but lower (57%) and with smaller lesions in Wistar rats. Serum cytokines leptin, CCL5, and VEGF concentrations showed a decrease in the hormone-treated rats compared to placebo-treated rats.

Conclusions

Prostate inflammation and obstructive voiding developed also in the Wistar rats but more slowly than in Noble rats. Male non-castrated Wistar strain rats may thus be suitable to use in studies of pathophysiology and hormone-dependent prostate inflammation and obstructive voiding.

Hypoxia exposure and B-type natriuretic peptide release from Langendorff heart of rats

Aim

We studied whether available oxygen without induced mechanical stretch regulates the release of the biologically active B‐type natriuretic peptide (BNP) from Langendorff heart.

Methods

Rat hearts were isolated and perfused with a physiological Krebs–Henseleit solution at a constant hydrostatic pressure in Langendorff set‐up. The basal O₂ level of perfusate (24.4 ± 0.04 mg L⁻¹) was gradually lowered to 3.0 ± 0.01 mg L⁻¹ over 20 min using N₂ gas (n = 7). BNP and O₂ level were measured from coronary flow. During control perfusions (n = 5), the O₂ concentration was kept at 26.6 ± 0.3 mg L⁻¹.

Results

A low oxygen concentration in the perfusate was associated with a significant increase in BNP release (F = 40.4, P < 0.001). Heart rate decreased when the oxygen concentration in the perfusate reached 9.1 ± 0.02 mg L⁻¹ and continued to fall in lower oxygen concentrations (F = 14.8, P < 0.001). There was also a significant but inverse correlation between BNP and oxygen in the coronary flow (R² = 0.27, P < 0.001).

Conclusion

In the spontaneously beating Langendorff rat heart, a decreasing concentration of oxygen in the ingoing perfusion increased the secretion of BNP. The effect of oxygen was independent of mechanical stretch of the heart as it occurred even when the heart rate decreased but the pressure conditions remained constant. The difference in the oxygen capacitance of blood and Krebs–Henseleit solution appears to be a major factor affecting secretion of BNP, which is correlated with the oxygen tension of myocardial cells and affected both by the oxygen concentration and capacitance of solution perfusing the heart and by the coronary flow.

Potentiation of Glibenclamide Hypoglycaemia in Mice by MK-467, a Peripherally Acting Alpha2-Adrenoceptor Antagonist

Pharmacological antagonism and genetic depletion of pancreatic α2A-adrenoceptors increase insulin secretion in mice and enhance the insulinotropic action of glibenclamide, a representative of the sulphonylurea class of insulin secretagogues used in the therapy of type 2 diabetes. Antagonism of α2-adrenoceptors in the central nervous system (CNS) causes tachycardia and hypertension, making generalized α2-adrenoceptor blockade unfavourable for clinical use despite its potential to decrease blood glucose levels. The purpose of this study was to test the acute effects of the peripherally acting α2-adrenoceptor antagonist MK-467 alone and in combination with glibenclamide in non-diabetic C57BL/6N mice. Cardiovascular safety was assessed in freely moving mice with radiotelemetry. Dose-dependent decreases in blood glucose and increases in plasma insulin concentrations were seen with the combination of MK-467 and glibenclamide; the combinations were much more potent than glibenclamide or MK-467 alone. Furthermore, MK-467 had no effect on mean arterial pressure or heart rate in freely moving mice and did not prevent the centrally mediated hypotensive effect of the α2-adrenoceptor agonist medetomidine. Thus, peripheral blockade of α2-adrenoceptors does not evoke the same cardiovascular adverse effects as antagonism of CNS α2-adrenoceptors. The current results indicate that the combined use of small doses of a peripherally acting α2-adrenoceptor antagonist with a sulphonylurea drug could provide a novel option for the treatment of type 2 diabetes, especially in patients with increased tonic α2-adrenoceptor-mediated inhibition of insulin secretion.

Hemodynamic actions and mechanisms of systemically administered α-MSH analogs in mice

α-Melanocyte-stimulating hormone (α-MSH) regulates important physiological functions including energy homeostasis and inflammation. Potent analogs of α-MSH, [Nle(4), D-Phe(7)]-α-MSH (NDP-α-MSH) and melanotan-II (MT-II), are widely used in pharmacological studies, but the hemodynamic effects associated with their systemic administration have not been thoroughly examined. Therefore, we investigated the hemodynamic actions of these compounds in anesthetized and conscious C57Bl/6N mice using peripheral routes of administration. NDP-α-MSH and MT-II induced mild changes in blood pressure and heart rate in anesthetized mice compared to the effects observed in conscious mice, suggesting that anesthesia distorts the hemodynamic actions of α-MSH analogs. In conscious mice, NDP-α-MSH and MT-II increased blood pressure and heart rate in a dose-dependent manner, but the tachycardic effect was more prominent than the pressor effect. Pretreatment with the melanocortin (MC) 3/4 receptor antagonist SHU9119 abolished these hemodynamic effects. Furthermore, the blockade of β(1)-adrenoceptors with metoprolol prevented the pressor effect and partly the tachycardic action of α-MSH analogs, while the ganglionic blocker hexamethonium abrogated completely the difference in heart rate between vehicle and α-MSH treatments. These findings suggest that the pressor effect is primarily caused by augmentation of cardiac sympathetic activity, but the tachycardic effect seems to involve withdrawal of vagal tone in addition to sympathetic activation. In conclusion, the present results indicate that systemic administration of α-MSH analogs elevates blood pressure and heart rate via activation of MC(3/4) receptor pathways. These effects and the consequent increase in cardiac workload should be taken into account when using α-MSH analogs via peripheral routes of administration.

Cannabinor, a selective cannabinoid-2 receptor agonist, improves bladder emptying in rats with partial urethral obstruction

PURPOSE

We studied the effects of chronic treatment with the novel selective cannabinoid 2 receptor agonist cannabinor (Procter & Gamble Pharmaceuticals, Cincinnati, Ohio) on bladder function in conscious rats with partial urethral obstruction and on the functional properties of isolated detrusor muscle.

MATERIALS AND METHODS

A total of 24 female Sprague-Dawley® rats with surgically created partial urethral obstruction received daily intraperitoneal injections of 3 mg/kg cannabinor (12) or saline as controls (12) for 2 weeks. Cystometry was done, the rats were sacrificed and the bladders were prepared for in vitro studies.

RESULTS

Mean ± SEM bladder weight was 0.97 ± 0.15 gm in controls and 0.53 ± 0.08 gm in cannabinor treated rats (p <0.05). There was no difference between the groups in the mean micturition interval, or mean baseline, threshold, flow or maximum pressure. In controls and cannabinor treated rats mean post-void residual volume was 0.28 ± 0.07 and 0.06 ± 0.02 ml, mean micturition compliance was 0.032 ± 0.006 and 0.069 ± 0.016 ml/cm H(2)O, and mean bladder wall force at the start of flow was 950 ± 280 and 1,647 ± 325 mN/gm, respectively (each p <0.05). Nonvoiding contractions were significantly less frequent in cannabinor treated rats than in controls. We noted no difference in carbachol (Sigma®) half maximum concentration between the groups but the carbachol maximum response in detrusor strips from cannabinor treated rats was significantly higher than that in control strips.

CONCLUSIONS

In rats with partial urethral obstruction treated daily for 14 days with cannabinor bladder weight was lower, the ability to empty the bladder was preserved and nonvoiding contraction frequency was low compared to those in controls. Detrusor preparations from cannabinor treated rats showed a higher response to nerve stimulation than those from controls. Selective cannabinoid 2 receptor activation may be a novel principle to enable improved bladder function after partial urethral obstruction.

Effects of cannabinor, a novel selective cannabinoid 2 receptor agonist, on bladder function in normal rats

BACKGROUND

Cannabinoid (CB) receptors may be involved in the control of bladder function; the role of CB receptor subtypes in micturition has not been established.

OBJECTIVES

Our aim was to evaluate the effects of cannabinor, a novel CB2 receptor agonist, on rat bladder function.

DESIGN, SETTING, AND PARTICIPANTS

Sprague Dawley rats were used. Distribution of CB2 receptors in sensory and cholinergic nerves of the detrusor was studied. Selectivity of cannabinor for human and rat CB receptors was evaluated. Effects of cannabinor on rat detrusor and micturition were investigated.

MEASUREMENTS

Immunohistochemistry, radioligand binding, tritium outflow assays, organ bath studies of isolated bladder tissue, and cystometry in awake rats were used.

RESULTS AND LIMITATIONS

CB2 receptor immunoreactivity was expressed in the urothelium and in sensory and cholinergic bladder nerves. Cannabinor exhibited similar binding at human and rat CB2 receptors and a 321-fold functional selectivity for the CB2 receptor versus the CB1 receptor. Cannabinor had no effect on isolated detrusor muscle function. In vivo, cannabinor 3.0mg/kg increased micturition intervals and volumes by 52% (p<0.05) and 96% (p<0.01), respectively, and increased threshold and flow pressures by 73% (p<0.01) and 49% (p<0.001), respectively. Cannabinor 0.3 or 1.0mg/kg or vehicle did not affect urodynamic parameters.

CONCLUSIONS

Considering that CB2 receptors are localized on sensory nerves and on the urothelium and that cannabinor had effects on "afferent" urodynamic parameters, peripheral CB2 receptors may be involved in sensory functions of rat micturition. Effects of cannabinor on cholinergic nerve activity in normal bladder tissue appear to be limited.

Human HSD17B1 expression masculinizes transgenic female mice

When present in excess amounts during fetal life, androgens can impair female development by inducing masculinization. On way to modify fetal steroid concentration is by altering the expression of hydroxysteroid (17beta) dehydrogenases (HSD17Bs). Human HSD17B1 converts weak estrogen estrone to estradiol, and with lower catalytic efficiency, weak androgen androstenedione to testosterone. We have recently shown that over-expression of human HSD17B1 in transgenic mice results in masculinized phenotype in female mice. In the present study, we further show that in addition to the Müllerian ducts, HSD17B1TG females have internal structures resembling Wolffian ducts, and enlarged Skene paraurethral gland, also called the female prostate. HSD17B1 expression has been found in fetal human ovary, thus, it is possible that HSD17B1 contributes to maintain the normal steroid hormone concentration during development. Thereby, abnormal increase in the fetal expression of HSD17B1 could contribute to the development of hormonal imbalances, and so result in female masculinization.

Distribution and function of cannabinoid receptors 1 and 2 in the rat, monkey and human bladder

PURPOSE

We investigated the distribution of cannabinoid receptor subtypes 1 and 2 in the detrusor of different species and studied the effects of cannabinoid receptor 1 and 2 agonists on bladder function.

MATERIALS AND METHODS

Cannabinoid receptor 1 and 2 expression was studied with Western blot and immunohistochemistry in rat, monkey and human detrusors. Co-staining was done for markers of sensory nerves using calcitonin gene-related peptide (Euro-Diagnostica, Malmö, Sweden) and transient receptor potential vanilloid 1, and for cholinergic nerves using VAChT (Santa Cruz Biotechnology, Santa Cruz, California). Actions of the endogenous cannabinoid receptor-1 and 2 agonist anandamide (Sigma(R)), and the cannabinoid receptor 1 and 2 agonist CP55,940 (Sigma) on isolated detrusor and during cystometry in conscious rats were recorded.

RESULTS

Higher expression of cannabinoid receptor 2 but not cannabinoid receptor 1 was noted in the mucosa than in the detrusor. Compared to the detrusor larger amounts of cannabinoid receptor 2 containing nerves that also expressed transient receptor potential vanilloid 1 or calcitonin gene-related peptide were observed in the suburothelium. Nerve fibers containing cannabinoid receptor 2 and VAChT were located in the detrusor. Neither anandamide nor CP55,940 affected isolated detrusor carbachol (Sigma) contractions. Nerve contractions were enhanced by 10 muM anandamide and decreased by 10 muM CP55,940 (p<0.05). In vivo CP55,940 increased the micturition interval by 46% and threshold pressure by 124% (p <0.05). Anandamide increased threshold pressure by 26% and decreased the micturition interval by 19% (p <0.05 and <0.01, respectively).

CONCLUSIONS

The distribution of cannabinoid receptor 2 on sensory nerves and in the urothelium, and effects by CP55940 on the micturition interval and threshold pressure suggest a role for cannabinoid receptor 2 in bladder afferent signals. Co-expression of VAChT and cannabinoid receptor 2, and effects by CP55940 on nerve contractions suggest a cannabinoid receptor 2 mediated modulatory effect on cholinergic nerve activity. Anandamide may not be a good tool for cannabinoid receptor studies due to its activity at other receptors.

Prostatic inflammation and obstructive voiding in the adult Noble rat: impact of the testosterone to estradiol ratio in serum

BACKGROUND

The age-related decline of the testosterone to estradiol (T-to-E(2)) ratio in serum is associated with the increased prevalence of prostatic inflammation and lower urinary tract symptoms suggesting obstructive voiding. The impact of the T-to-E(2) ratio on the development and reversal of non-bacterial prostatic inflammation and obstructive voiding was tested in adult Noble rats.

METHODS

Adult male Noble rats (n = 16) were treated with estradiol (83 microg/day) and two different doses (280 and 830 microg/day) of testosterone to cause hypoandrogenic and hyperandrogenic states with elevated estrogen. After the 13-week hormonal treatment, urodynamical measurements and electrical activity recording of the rhabdosphincter muscle were performed under anesthesia. Testosterone, estradiol, and prolactin concentrations in serum were measured and inflammatory changes in the dorsolateral prostate were classified and counted.

RESULTS

Histopathological and urodynamical analyses indicated that the hypoandrogenic animals with a decreased T-to-E(2) ratio (10 versus > 300 in control) developed prostatic inflammation and non-obstructive voiding. The hyperandrogenic state with decreased T-to-E(2) ratio of 50 decreased the aggressiveness of the inflammation and the number of inflamed acini in the prostate and caused urethral obstruction associated with rhabdosphincter dysfunction.

CONCLUSIONS

Different responses of the prostatic inflammation and voiding function to the change in T-to-E(2) ratio imply that non-bacterial prostatic inflammation is not a sufficient condition for the development of obstructive voiding. The present study finds no support for the idea that age- and/or obesity-related hypoandrogenic state with a decreased ratio of T-to-E(2) would cause urethral obstruction.

Effects of Tolterodine on Afferent Neurotransmission in Normal and Resiniferatoxin Treated Conscious Rats

PURPOSE

The beneficial effects of antimuscarinics on detrusor overactivity and overactive bladder syndrome are exerted during bladder filling, when there is no parasympathetic outflow from the spinal cord. We tested the hypothesis that, if tolterodine exerts some of its effects on afferent nerves, the functional elimination of C-fiber afferents should affect the actions of the drug on urodynamic parameters.

MATERIALS AND METHODS

The study was performed in normal female Sprague Dawley rats and rats treated with resiniferatoxin to eliminate vanilloid sensitive afferent nerves. Tolterodine was given intravenously to normal and resiniferatoxin treated animals. To test if tolterodine at the doses used affects efferent neurotransmission the drug was given to normal and resiniferatoxin treated animals in which detrusor activity was induced by apomorphine.

RESULTS

In resiniferatoxin treated animals (0.3 mg kg-1 subcutaneously) the mean micturition interval and volume, and mean residual volume increased significantly compared to those in controls. Baseline and micturition pressures in control and resiniferatoxin treated animals were similar, whereas threshold pressures were higher in resiniferatoxin treated animals. In controls 10 microg kg-1 tolterodine administered intravenously increased the mean micturition interval, bladder capacity and micturition volume. In resiniferatoxin treated rats 1 and 10 microg kg-1 tolterodine increased the mean micturition interval, bladder capacity and micturition volume. Subcutaneous administration of 100 microg kg-1 apomorphine induced detrusor overactivity in all rats. The AUC of intravesical pressure during the initial 10 minutes from the start of detrusor overactivity showed no difference between normal and resiniferatoxin treated rats with or without tolterodine pretreatment.

CONCLUSIONS

Tolterodine increased the micturition interval and bladder capacity in controls and in resiniferatoxin treated animals, suggesting that these effects were exerted independently of resiniferatoxin sensitive afferents. Tolterodine did not decrease the contractile effects of apomorphine at the doses used, suggesting that the drug had no effect on efferent neurotransmission during voiding.

Urodynamic changes in a noble rat model for nonbacterial prostatic inflammation

BACKGROUND

Chronic nonbacterial prostatitis (CP) associated with voiding dysfunction is a poorly understood clinical phenomenon. The goal of the present study was to induce prostatic inflammation with estrogen and androgen treatment and to record associated urodynamic changes in Noble rats.

METHODS

Rats were treated with estradiol and testosterone implants to increase estradiol concentration in serum while testosterone concentration was maintained at or slightly above the control level. The urodynamical recordings were performed under anesthesia after the hormone treatments for 3 and 6 weeks. The dorsolateral lobes of the prostates were removed for histopathological analysis after recordings.

RESULTS

After the 3-week treatment, lymphocytes, mainly T-cells, were located around the capillaries. During the following 3 weeks lymphocytes migrated into stroma and acini. Cytotoxic T-cells were seen intraepithelially, and neutrophiles inside the acini. Removal of estrogen implant or treatment with anti-estrogen diminished inflammation. No changes in voiding pattern were seen after the 3-week treatment. Three weeks later, bladder weight and capacity were increased, and the micturition time was prolonged.

CONCLUSIONS

Elevated estrogen concentration was essential for the gradual development of prostatic inflammation. The profile and location of inflammatory cells suggest that prostatic vasculature is one of the sites of estrogen action. Urodynamic changes which developed in association with glandular inflammation indicated abnormal bladder function, reflecting an incipient obstruction.

The soy effect in the disease models of nonbacterial prostatitis and obstructive voiding

The goal of this study was to improve the understanding of the potential significance of dietary soy for human health by investigating its effects in the animal models of nonbacterial prostatitis and urethral obstruction. Nonbacterial prostatitis was induced in adult Noble rats with the combined treatment of testosterone and 17beta-estradiol. The inflammatory foci categorized into three forms were counted and correlated with expression of an estrogen-responsive gene, progesterone receptor (PR), in the dorsolateral lobes of the rats on soy (+) and soy (-) diets. Development of obstructive voiding after neonatal estrogenization of Noble rats (NeoDES rats) was followed with urodynamic measurements in rats on soy (+) and soy (-) diets. The amounts of genistein and daidzein, two major soy-derived isoflavones, were measured in the urine of Noble rats by the high-performance liquid chromatography-photodiodearray method. Dietary soy decreased the total number of inflammatory foci while no demonstrable effects were seen on the cellular composition of the infiltrates. Soy did not increase the weights of the pituitary gland, testes, or sex accessory glands, but it did increase the number of PR-positive epithelial cells in the dorsolateral prostate. It also decreased the bladder pressures in NeoDES rats but did not increase the flow rates. The soy effects may be mediated by the strong estrogen influence involved in the animal models. Dietary soy had anti-inflammatory effects in the prostate but only marginal effects on the development of obstructive voiding in Noble rats. The anti-inflammatory effects of soy may contribute to the lower prevalence of prostatitis-like symptoms and the historically lower risk of benign prostatic hyperplasia in Japan; however, no evidence was found that regular consumption of soy influences the age-related development of lower urinary tract symptoms or decline of flow rate.

Simultaneous registration of intraabdominal and intravesical pressures during cystometry in conscious rats—Effects of bladder outlet obstruction and intravesical PGE2

AIMS

A method was developed and evaluated to simultaneously register intraabdominal pressure (IAP) and intravesical pressure (IVP) during cystometry in conscious rats. In addition, IAP and IVP were recorded in rats with experimental detrusor overactivity (DO).

METHODS

Sprague Dawley rats (n = 24) were used. Six female rats were subjected to partial bladder outlet obstruction for 2 weeks. A catheter was implanted into the bladder to record the IVP, and a balloon-fitted catheter was positioned in the abdominal cavity to record the IAP. PGE(2) was given intravesically to induce DO. Detrusor pressure (DP) was defined as the IVP corrected for IAP.

RESULTS

Recorded as increases in IAP, all rats of both sexes exhibited abdominal straining during every void. In controls, a maximal IAP of 6.0 +/- 1.4 cmH(2)O (range 3-15 cmH(2)O) was registered (n = 12) at the time of the flow pressure (FP). Intravesical administration of PGE(2) or BOO did not affect the IAP at basal pressure, FP or micturition pressure. Changes in IAP due to movement or non-voiding-related straining were subtracted from IVP to generate DP and to visualize DO after BOO or intravesical PGE(2).

CONCLUSIONS

The conscious rat uses abdominal straining during voiding, and maximal IAP is recorded at the onset of urinary flow. Simultaneous registration of IAP and IVP during the micturition cycle in conscious rats is a convenient method for accurate quantification of pressures inside the bladder and for studying "true" DO without interference from movement artifacts.

Phasic non-micturition contractions in the bladder of the anaesthetized and awake rat

OBJECTIVE

To characterize the contractile activity that occurs in the bladder during the filling phase of the micturition cycle (non-micturition contractions, NMCs), which generate transient rises in intravesical pressure not associated with urine flow.

MATERIALS AND METHODS

The experiments were conducted using anaesthetized (chloral hydrate) and un-anaesthetized rats. In un-anaesthetized rats bladder contractile activity was measured using an intravesical cannula implanted under full surgical anaesthesia 3 days previously. In the anaesthetized rats the bladder was exteriorized and a cannula inserted through the dome. In these experiments electrical activity within the detrusor was also measured with a suction electrode on the bladder surface. For each rat, the experimental protocol involved filling the bladder at a constant rate (10 mL/h) to evoke micturition cycles, or infusion of a fixed volume and recording made under effective isovolumetric conditions.

RESULTS

In both anaesthetized and un-anaesthetized rats there were transient rises in bladder pressure (0.5-3 cmH2O). In the anaesthetized rats the amplitude of the transients increased throughout the filling phase, with little change in frequency. The phasic NMCs generating these pressure transients were accompanied by electrical changes in the detrusor. In the middle phase of bladder filling the slow pressure changes were accompanied by slow waves of electrical activity which changed in the pressure cycles immediately before micturition to high-frequency low-amplitude signals. In the un-anaesthetized rats there was a period immediately after voiding where there was no activity. As filling proceeded, low-amplitude low-frequency NMCs appeared that gradually increased in frequency and amplitude during the filling phase. However, the frequency of the transients decreased immediately before micturition despite an increase in amplitude. Similar responses were seen during isovolumetric recording.

CONCLUSION

The present results show the presence of NMCs in the rat bladder, identify volume-dependent changes in the pattern of this activity during the micturition cycle, and show that NMCs are accompanied by electrical changes in the detrusor. The physiological significance of NMCs is not known but it might be linked to the generation of afferent discharge from mechanoreceptors in the wall, so contributing to sensations related to bladder volume.

Oral treatment with a vitamin D3 analogue (BXL628) has anti-inflammatory effects in rodent model of interstitial cystitis

OBJECTIVE

To investigate the effects of a vitamin D3 analogue (BXL628) in a model of chronic cystitis, as calcitriol analogues might be an interesting new therapeutic option for interstitial cystitis, for although the cause of the disease remains unclear, the increase in mast cells in the mucosa and detrusor muscle are significant.

MATERIALS AND METHODS

We devised a mouse model of allergen-induced allergic cystitis that is associated with the up-regulation of genes for interleukin-13, FcepsilonRIalpha and mast cells-derived proteases, a massive inflammatory reaction in the bladder tissue, and augmented levels of mast cell-derived protease 1 (MMCP1) detected in mouse sera.

RESULTS

Oral administration of BXL628 significantly reduced the expression of interleukin-13, FcepsilonRIalpha and MMCP1 in the bladder. Furthermore, histological analysis showed a decrease in oedema and leukocyte infiltration in the bladder wall. BXL628 treatment reduced serum MMCP1 levels, indicating an effect on mast cell degranulation in vivo.

CONCLUSIONS

Vitamin D3 analogues may successfully be used as anti-inflammatory agents in allergen-mediated inflammatory reactions. Moreover, the modulatory effect shown on mast cell activation by the BXL628 analogue strongly supports its potential therapeutic use in a possibly mast cell-dependent disease such as human interstitial cystitis.

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.

The role of corticotropin releasing factor and its antagonist, astressin, on micturition in the rat

The purpose of this investigation was to evaluate the role of corticotropin releasing factor (CRF) on micturition. CRF is involved in the endocrine and central nervous system responses to stress and is also expressed in sites responsible for the control of micturition. In this investigation, cystometric experiments were performed in awake and unrestrained Wistar rats and on Spontaneous Hypertensive Rats, which are used as a rodent model of detrusor overactivity and anxiety. In vitro effects of CRF were evaluated using strips of detrusor muscle in an organ bath preparation. CRF (6.0 microg) administered via intrathecal and intraperitoneal routes, but not intracerebroventricularly, lowered the micturition threshold. CRF reduced the intercontraction interval by 28% and 26% after intrathecal or intraperitoneal administration, respectively, and reduced micturition volume by 34.7% and 30.2%, respectively. In Wistar-Kyoto rats, 6.0 microg intrathecal CRF significantly reduced intercontraction interval (423 +/- 79 vs. 669 +/- 59 s) and micturition volume (0.30 +/- 0.04 vs. 0.69 +/- 0.07 ml) compared to controls that received saline vehicle. These effects were blocked by pretreatment with 6.0 mug intrathecal astressin, a potent CRF antagonist, demonstrating that the effects are CRF receptor mediated. In Spontaneous Hypertensive Rats, 6.0 mug intrathecal CRF was found to have minimal stimulatory effects on the bladder, whereas astressin reduced baseline detrusor overactivity. CRF had no direct contractile effects on detrusor muscle strips. These results demonstrate that in the absence of detrusor overactivity, CRF stimulates micturition when administered via the intrathecal or intraperitoneal routes. Further studies are needed to explore the possibility whether CRF antagonists are effective for detrusor overactivity and the overactive bladder syndrome.

Sex specific expression of progesterone receptor in mouse lower urinary tract

Progesterone receptor (PR) was investigated immunohistochemically in the lower urinary tract of the male and female mouse. Estrogen receptor (ER)-subtype-deficient mice (ERKO, BERKO) were used to determine the possible regulation of PR expression in an ER-subtype-specific manner. PR was found to be co-expressed with ERalpha in cell nuclei of urothelium, lamina propria fibroblasts and smooth muscle cells in the female urethra. Only few PR positive cells were seen in female ERKO mice. Ovariectomy reduced and estrogen treatment restored the urethral PR expression in female wild type and BERKO mice. Thus, the expression of PR in the female urethra is estrogen-inducible via ERalpha. In male urethra, PR was co-expressed with ERbeta in the rhabdosphincter. In male, no evidence was obtained for the ER-linked control of the PR expression. No PR-positive cells were observed in the body of the bladder of either sex or any strain.

Urodynamic effects of the K+ channel (KCNQ) opener retigabine in freely moving, conscious rats

PURPOSE

Retigabine is a novel anticonvulsant drug that not only augments gamma-aminobutyric acid mechanisms, but also opens voltage gated K+ channels (KCNQ). In this study we investigated the effects of retigabine on detrusor activity in rats.

MATERIALS AND METHODS

To conscious, female Sprague-Dawley rats undergoing continuous cystometry retigabine was given intravenously (0.5, 1 and 5 mg/kg(-1)). The KCNQ channel blocker linopirdine was given intravenously (2 mg/kg(-1)) 5 minutes prior to retigabine (1 mg/kg(-1)). In addition, retigabine was given intracerebroventricularly (1, 5 and 10 microg) and intravesically (100, 500 and 1,000 ng ml(-1)). The effects of the drug (intravesical administration) on capsaicin induced bladder overactivity were also tested.

RESULTS

Retigabine given intravenously (1 mg/kg(-1)) decreased baseline and maximal bladder pressures, increased voided and infused volumes, and increased voiding intervals. Retigabine (10 microg) given intracerebroventricularly decreased baseline pressure and increased voided and infused volumes as well as voiding intervals. However, bladder pressures were not significantly affected. Intravesical retigabine (1,000 ng.ml(-1)) decreased maximal bladder pressure, increased voided and infused volumes, and increased voiding intervals. Given intravesically for 30 minutes prior to intravesical capsaicin (30 microM) instillation retigabine (1,000 ng.ml(-1)) decreased the detrusor overactivity induced by capsaicin. The KNCQ channel blocker linopirdine (2 mg/kg(-1)) completely blocked the effects of intravenous retigabine (1 mg/kg(-1)).

CONCLUSIONS

Retigabine given intravenously, intracerebroventricularly and intravesically increased micturition volume and voiding intervals and, when given intravesically, it decreased capsaicin induced detrusor overactivity, suggesting that KCNQ channels can be interesting targets for drugs aiming at micturition control. Retigabine may be a candidate to test as a treatment for detrusor overactivity in humans.

Transmitters contributing to the voiding contraction in female rats

OBJECTIVES

To assess in detail the contribution of acetylcholine and ATP to the different phases of the voiding contraction, urine flow and rhabdosphincter electromyographic (RB-EMG) activity in rats, using alpha,beta-methylene-ATP (desensitizing purinoceptors) and atropine (blocking muscarinic receptors). These agents and possibly other transmitters contribute to bladder emptying in rats, but how they contribute to the different phases of the micturition cycle, including the intraluminal pressure high-frequency oscillations (IPHFOs) is unclear.

MATERIALS AND METHODS

Adult anaesthetized female Sprague-Dawley rats were used; intravesical pressure, RB-EMG and urine flow from the distal urethra were recorded. After baseline recordings, alpha,beta-methylene-ATP (0.5 mg/kg), atropine (1 mg/kg), or both, were injected intravenously.

RESULTS

Alpha,beta-Methylene-ATP significantly decreased the maximum bladder pressure during the first micturition phase, whereas atropine had little effect; the maximum bladder pressure during the second phase was also reduced. IPHFOs were apparent after both treatments. Atropine significantly reduced the maximum bladder pressure during the third phase. The maximum urinary flow rate was reduced by both alpha,beta-methylene-ATP and atropine; after exposure to both agents together, urinary flow was markedly reduced or stopped, and overflow incontinence developed.

CONCLUSIONS

ATP contributes mainly to the initial and acetylcholine to the later phases of the voiding cycle in the rat. Neither agent abolished the IPHFOs; even after blocking the receptors for one transmitter and in the presence of IPHFOs, the bladder can still empty. However, if both receptors are blocked, overflow incontinence develops, suggesting that even if further transmitters are taking part in the voiding contraction, their physiological significance is questionable.

The role of the rhabdosphincter in female rat voiding

OBJECTIVES

To obtain information on the mechanisms of female rat micturition using a model in which pressure was measured in the bladder and distal part of the urethra corresponding to the location of the rhabdosphincter, providing information on the role of the sphincter in opening and closing the urethral lumen.

MATERIALS AND METHODS

A micturition reflex was induced in adult anaesthetized (chloral hydrate and urethane) female rats by filling the bladder with saline. Bladder pressure (BP), urethral pressure (UP), electromyography (EMG) of the middle part of the rhabdosphincter, and urinary flow rate in the distal urethra were simultaneously recorded.

RESULTS

There were four phases of the micturition contraction, the second characterized by intraluminal pressure high-frequency oscillations (IPHFOs) of BP. When a non-oscillatory micturition contraction started, the BP increased and exceeded UP for the rest of the micturition contraction. Even though the BP increased during this first phase, the urethral lumen stayed closed. Its opening was indicated by a simultaneous decrease in BP and increase of UP as the fluid flowed from the bladder to the urethra. When the rhabdosphincter closed, as indicated by an EMG-burst of the muscle, the UP declined, bladder pressure increased and the flow ceased. Because of momentary contractions of the rhabdosphincter, the UP and urine flow rate had the same periodicity as the IPHFOs of BP.

CONCLUSIONS

The simultaneous recording of the BP, UP, EMG of the rhabdosphincter and urinary flow rate showed the sequence of events during micturition. The rhabdosphincter acts as an 'on-off' switch, causing interruptions in the urinary flow rate.

Multiple structural and functional abnormalities in the p450 aromatase expressing transgenic male mice are ameliorated by a p450 aromatase inhibitor

The present study was undertaken to analyze the effect of a P450 aromatase inhibitor (finrozole) on 4-month-old transgenic mice expressing human P450 aromatase (P450arom) under the human ubiquitin C promoter (AROM+). AROM+ mice present several dysfunctions, such as adrenal and pituitary hyperplasia, cryptorchidism, Leydig cell hypertrophy and hyperplasia, and gynecomastia. The present study demonstrates that these abnormalities were efficiently treated by administration of a P450arom inhibitor, finrozole. The treatment normalized the reduced intratesticular and serum testosterone levels, while those of estradiol were decreased. The body weight and several affected organ weights were normalized with the treatment. Histological analysis revealed that both the pituitary and adrenal hyperplasia were diminished. Furthermore, the cryptorchid testes present in the untreated AROM+ males descended to scrotum, 4 to 15 days after inhibitor treatment. In addition, the disrupted spermatogenesis was recovered and qualitatively complete spermatogenesis appeared with the inhibitor treatment. This was associated with normalized structure of the interstitial tissue, as analyzed by immunohistochemical staining for Leydig cells and macrophages. One of the features was that the Leydig cell hypertrophy was markedly diminished in the treated mice. AROM+ mice also present with severe gynecomastia, while the development and differentiation of the mammary gland in AROM+ males was markedly diminished with the inhibitor treatment. Interestingly, the mammary gland involution was associated with the induction of androgen receptor in the epithelial cells, while estrogen receptors were still detectable in the epithelium. The data show that AROM+ mouse model is a novel tool to further analyze the use of P450arom inhibitors in the treatment of the dysfunctions in males associated with misbalanced estrogen to androgen ratio, such as pituitary adenoma, testicular dysfunction, and gynecomastia.

Phenotype characteristics of transgenic male mice expressing human aromatase under ubiquitin C promoter

To study the significance of the increased ratio of the estrogen/androgen concentration for the male reproductive functions, we have generated transgenic mice expressing human P450 aromatase under a promoter providing ubiquitous and permanent transgene expression (AROM+ mice). AROM+ male mice are characterized by elevated serum estradiol and prolactin (Prl) concentrations, combined with markedly reduced testosterone levels. The mice are present with a multitude of structural and functional alterations in the reproductive organs such as cryptorchidism, Leydig cell hyperplasia, disrupted spermatogenesis and infertility. Furthermore, the mice develop infravesical obstruction associated with the rhabdosphincter atrophy and rudimentary accessory sex glands. Interestingly, the mammary gland in AROM+ males undergo a ductal and alveolar development morphologically resembling terminally differentiated female mammary glands, and express several signaling proteins typical for female mammary glands. Some of the abnormalities seen in AROM+ mice are similar to those described in both mice and humans exposed to diethylstilbestrol (DES) in utero. The importance of the AROM+ model may lie in its predictability, i.e. the model suggests which abnormalities of the human reproductive functions may be associated with the increased ratio of estrogen/androgen concentrations in early life and at adult age as well.

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.

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.

Mammary gland development in transgenic male mice expressing human P450 aromatase

We recently generated a transgenic mouse strain that expresses the human aromatase gene under the ubiquitin C promoter (AROM+). We have previously shown that in these mice the serum estradiol concentration is highly elevated, whereas the testosterone concentration is decreased. In the present study we examined mammary gland development in AROM+ male mice at different ages and found that the mammary glands of AROM+ males undergo ductal and alveolar development morphologically resembling that of terminally differentiated female mammary glands, expressing mRNA for a milk protein gene (beta-casein). The male mammary glands also express multiple hormone receptors typical for female mammary gland: estrogen receptor alpha and beta, progesterone receptor, and PRL receptor. Furthermore, data showed activation of the Stat5 (signal transducer and activator of transcription 5) signaling pathway in the AROM+ male mammary gland. Interestingly, the phenotype observed is in part reversible. Treatment with finrozole, a specific aromatase inhibitor, caused an involution of the differentiated phenotype of the mammary gland, marked by the disappearance of alveolar structures and the majority of the tertiary side branches of the ducts. The present animal model is a valuable tool for better understanding the cellular and molecular mechanisms involved in the development of gynecomastia.

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.

Similarities and differences in female and male rat voiding

We measured in adult rats, under anaesthesia, bladder pressure by transvesical cystometry and flow rate by an ultrasound transducer in the distal urethra. The urinary flow was discontinuous in both sexes. No difference between the sexes in bladder pressure oscillations or in non-oscillatory voiding was found but during the oscillatory activity there was a difference in the relationship between bladder pressure and urinary flow. In the female, the bladder pressure decreased when the flow started and increased when the flow decreased resembling species whose urinary flow is continuous. Basically the flow was stable but it was divided into periods of variable duration by full or partial closure of urethral sphincter. In the male rat, the oscillatory flow consisted of short, fast spikes occurring just before the bladder pressure reached the maximum, after which the flow spike decreased slowly. Overall, no differences were seen in bladder pressure data between the genders. However, the maximal flow rate was lower and micturition time was shorter in female rats. When we recorded occasionally occurring micturitions without high-frequency oscillations of intraluminal pressure (IPHFOs) (non-oscillatory voiding), no differences between the genders were seen. The difference during oscillatory voiding between male and female rat can be understood against anatomical and hormonal backgrounds, and by the relative role of rhabdosphincter, which did not activate during non-oscillatory voidings when no differences were detected.

Possible action of the proximal rhabdosphincter muscle in micturition of the adult male rat

Micturition requires high bladder pressure and simultaneous opening of the urethra. In adult male rat, a rhabdosphincter (RB) is known to be electrically active when the bladder pressure is high. This indicates a closure rather than an opening of the urethra, which is inconsistent with the requirements of optimal urodynamics. In order to solve this problem, we simultaneously recorded electromyogram (EMG) of the proximal RB, bladder pressure, and flow rate. Micturition was evoked by an increased volume of saline in the bladder. A computer-based recording device was used with minimal filtering. The EMG was recorded with a monopolar flexible suction electrode. The suction electrode records action potentials resembling those obtained with a microelectrode technique. During the early high-frequency intraluminal pressure oscillation period (IPHFO), the increase of pressure initially associated with a decrease of potential of the RB. When the first flow peak appeared, the relationship of the bladder pressure and RB single EMG activities changed. The increasing pressure coincided with the positive potential wave (depolarisation). It was interrupted by a transient negative polarity period called transient repolarisation (TRP) coinciding with a flow rate peak, thus indicating an opening of the RB lumen. After the TRP, the depolarisation continued. Additional experiments employing different methods are needed for positive identification of the TRP mechanism.

Altered structure and function of reproductive organs in transgenic male mice overexpressing human aromatase

Aromatization of androgens is a key step in estrogen production, and it regulates the delicate balance between estrogens and androgens in the gonads and sex steroid target tissues. In the present study, we generated transgenic mice (AROM(+)) bearing the human ubiquitin C promoter/human P450 aromatase fusion gene. AROM(+) male mice are characterized by an imbalance in sex hormone metabolism, resulting in elevated serum E(2) concentrations, combined with significantly reduced testosterone and FSH levels, and elevated levels of PRL and corticosterone. AROM(+) males present a multitude of severe structural and functional alterations in the reproductive organs, such as cryptorchidism associated with Leydig cell hyperplasia, dysmorphic seminiferous tubules, and disrupted spermatogenesis. The males also have small or rudimentary accessory sex glands with abnormal morphology; a prominent prostatic utricle with squamous epithelial metaplasia, and edema in the ejaculatory ducts and vas deferens. In addition, the abdominal muscle wall is thin, and the adrenal glands are enlarged, with cortical hyperplasia. Some of the abnormalities, such as undescended testes and undeveloped prostate, resemble those observed in animals exposed perinatally to high levels of exogenous estrogen, indicating that the elevated aromatase activity results in excessive estrogen exposure during early phases of development. Some of the disorders in the reproductive organs, furthermore, can be explained by the fact that AROM(+) males are hypoandrogenic, and have elevated levels of serum PRL and corticosterone. Thus, the AROM(+) mouse model provides a novel tool to investigate the consequences of a prolonged increase in conversion of androgens to estrogens which results in complex hormonal disturbances altering the structure and function of various male reproductive organs.

Constant expression of cyclooxygenase-2 gene in prostate and the lower urinary tract of estrogen-treated male rats

Expression of cyclooxygenase-2 (E. C. 1.14.99.1) in prostate and the lower urinary tract (LUT) of the neonatally estrogenized male rat has been studied by using a COX-2's PCR fragment of 724 nt spanning 3 introns and a 478nt internal standard for quantitative RT-PCR. The same fragment of 724 nt was used for RNA probe in Northern hybridization. Neonatal estrogenization (10 microg/day of diethylstilbestrol on days 1-5) had no effect on COX-2 expression in prostatic urethra, prostatic lobes, or bladder. Acute estrogen treatment of castrated animals did not induce COX-2 expression, either. In addition the differential expression of basal level of COX-2 in the different lobes of prostate in normal rat was demonstrated. Our results suggest a constant expression of COX-2 gene in prostate and the lower urinary tract of the neonatally estrogenized (neoDES) rats. The present study indicates that the increased expression of COX-2 is probably not essential for the estrogen-driven development of stromal inflammation or hyperplastic and dysplastic alterations in the prostate of neoDES rats.

Nontraumatic urethral dyssynergia in neonatally estrogenized male rats

PURPOSE

Bladder outlet obstruction develops in estrogen treated males. Because of the lack of electromyography recordings, earlier studies have not clarified the failure mechanisms of voiding. We simultaneously recorded electromyography activity of the proximal rhabdosphincter in neonatally estrogenized rats with transvesical cystometry and urethral flow, followed by morphometric analysis of the urethral structure.

MATERIALS AND METHODS

Rats treated neonatally with 10 microg. diethylstilbestrol daily on days 1 to 5 after birth were used in urodynamics and morphological studies at ages 5 to 6.5 months. Using anesthesia the bladder, anterior surface of the proximal rhabdosphincter and distal urethra were exposed to record simultaneously the high frequency oscillations of intraluminal bladder pressure, and the rates of intermittent flow from the distal urethra and electromyography activity of the proximal rhabdosphincter with a suction electrode.

RESULTS

Neonatally estrogenized rats had higher mean maximal bladder pressure plus or minus standard deviation (42.1 +/- 6.4 versus 37.7 +/- 4.9 mm. Hg, p = 0.01), decreased mean flow (2.3 +/- 0.1 versus 4.1 +/- 1.6 ml. per minute, p < 0.0001) and mean increment of proximal rhabdosphincter electromyography depolarization amplitude (3.0 +/- 0.78 versus 2.6 +/- 0.87 mV., p = 0.02) compared with controls, while mean transient repolarization was absent or highly decreased (-0.3 +/- 0.61 versus 0.3 +/- 0.9 mV., p = 0.04). Morphologically the proximal rhabdosphincter was atrophied with increased connective tissue.

CONCLUSIONS

Alterations in the structure and electromyography activity of the urethral musculature imply that neonatal exposure to diethylstilbestrol predisposes male rats to urethral atrophy and dyssynergia, evident as altered electromyography activity of the proximal rhabdosphincter.

Distribution of collagen XII and XIV in the bladder wall of the male rat with outlet obstruction

PURPOSE

Our previous studies indicate that neonatal estrogenization with diethylstilbestrol (neoDES) of male mice and rats causes partial outlet obstruction. In the present study, type XII and XIV collagens were localized in the bladder to study their role in the development of obstruction.

MATERIALS AND METHODS

The bladder sections immunostained with smooth muscle specific a-actin antibody were double labeled either with collagen type XII or type XIV antibodies. The specimens were then analyzed with conventional and confocal fluorescence microscope.

RESULTS

Type XII and XIV collagens were not evenly distributed in the bladder. Further, in neonatally estrogenized rats collagen XIV appeared inside smooth muscle fascicles.

CONCLUSIONS

Non-overlapping distributions of collagen XII and XIV suggest their different roles in the urinary bladder. Penetration of collagen XIV inside smooth muscle fascicles may have a role in the development of DES-induced partial outlet obstruction.

Dietary phytoestrogens and their role in hormonally dependent disease

Epidemiological studies suggest that diets rich in phytoestrogens (plant estrogens), particularly soy and unrefined grain products, may be associated with low risk of breast and prostate cancer. It has also been proposed that dietary phytoestrogens could play a role in the prevention of other estrogen-related conditions, namely cardiovascular disease, menopausal symptoms and post-menopausal osteoporosis. However, there is no direct evidence for the beneficial effects of phytoestrogens in humans. All information is based on consumption of phytoestrogen-rich diets, and the causal relationship and the mechanisms of phytoestrogen action in humans still remain to be demonstrated. In addition, the possible adverse effects of phytoestrogens have not been evaluated. It is plausible that phytoestrogens, as any exogenous hormonally active agent, might also cause adverse effects in the endocrine system, i.e. act as endocrine disrupters.