The microvascular architecture of the rat vagina revealed by image analysis of vascular corrosion casts

Effects of natural mating, artificial insemination and intravaginal deposition of raw semen or seminal plasma on vaginal and uterine blood flow in German Holstein cows

AIM

The present study was performed to characterize and compare the perfusion of vaginal and uterine arteries after challenging the reproductive tract of dairy cows via natural mating, artificial insemination (AI), or intravaginal deposition (vaginal fundus) of different biological fluids or a placebo.

MATERIALS AND METHODS

In a double-blind study, six German Holstein cows were administered PGF2α during dioestrus and 48 h later treated with GnRH. Intravaginal or intrauterine treatments were carried out 12 h after GnRH was administered. Animals served as their controls, using a cross-over design with an interval of 14 days between experiments. The experimental animals were allocated to receive the following treatments: natural mating (N), intrauterine artificial insemination (A), intravaginal deposition (vaginal fundus) of 6 mL raw semen (R) or 6 mL seminal plasma (S), and compared to their controls [control 1: 6 mL placebo (P: physiological saline); control 2: no treatment (C)). Corresponding time intervals were chosen for the untreated control oestrus. Blood flow volume (BFV) in the uterine (u) and vaginal (v) arteries ipsilateral to the ovary bearing the preovulatory follicle was determined using transrectal Doppler sonography.

RESULTS

All animals exhibited oestrus and ovulated between 30 and 36 h after GnRH. Transient increases (P < 0.05) in vaginal blood flow occurred between 3 and 12 h following mating as well as 3 to 9 h after deposition of raw semen and seminal plasma, respectively. The most distinct increases (199%) in vBFV occurred 6 h after mating compared to values immediately before mating (= time 0 h). Neither AI nor deposition of a placebo into the vagina affected vBFV (P > 0.05). Only mating and deposition of either raw semen, seminal plasma or AI increased uBFV (P < 0.003). The greatest rise in uBFV occurred after natural mating. Maximum uBFV values were detected 9 h after mating when values were 79% greater (P < 0.05) than at 0 h.

CONCLUSIONS

The natural mating, deposition of raw semen or seminal plasma and conventional AI affect vaginal and/or uterine blood flow to different degrees. The factors responsible for these alterations in blood flow and their effects on fertility remain to be clarified in future studies.

Effects of retinoid-loaded hyaluronic acid nanomicelles on vaginal epithelium in a murine menopause model

PURPOSE

This study aimed to develop hyaluronic acid (HA)-based, retinoic acid (RA)-containing nanomicelles and to investigate the effects of these newly developed nanomicelles on regeneration of the vaginal epithelium and aquaporin 3 (AQP3) expression in a murine menopause model.

MATERIALS AND METHODS

The HA-based, RA-loaded nanomicelles were developed, and the RA-loading rate, encapsulation efficiency, and hydrodynamic diameter were measured. Female BALB/c mice (8 weeks; n=30) were divided into control and experimental groups. Menopause was established in the experimental group by removing both ovaries. The experimental group was further divided into an ovariectomy group, an HA-C18 vehicle group, and an HA-C18-RA group (2.5 µg per mouse); vaginal administration of HA-C18 or HA-C18-RA was performed once daily. After 4 weeks of treatment, murine vaginal tissue was removed, and histological analysis was performed.

RESULTS

Three drug-loaded nanomicelles were synthesized: the RA content in HA-C18-RA-10, HA-C18-RA-20, and HA-C18-RA-30 was 3.13%, 2.52%, and 16.67%, respectively, and the RA encapsulation efficiency was 95.57%, 83.92%, and 93.24%, respectively. In the experimental versus control group, serum estrogen levels were significantly reduced, and the vaginal mucosal epithelial layer was significantly thinner. After 4 weeks of treatment, the thickness of the vaginal mucosal epithelial layer and AQP3 expression was increased in the HA-C18-RA group compared with the HA-C18 vehicle group.

CONCLUSIONS

The newly developed HA-based nanomicelles containing RA resulted in vaginal epithelial recovery and increased AQP3 expression. The results may contribute to the development of functional vaginal lubricants or moisturizers for the treatment of vaginal dryness.

Smooth Muscle Organization and Nerves in the Rat Vagina: A First Look Using Tissue Clearing and Immunolabeling

Smooth muscle fibers within the vagina, as well as the nerve fibers that contribute to their control mechanisms, are important for the maintenance and alteration of vaginal length and tone. Vaginal smooth muscle (VaSM) is typically described as being arranged into two distinct concentric layers: an inner circular muscular layer and an outer longitudinal muscular layer. However, the distribution of VaSM oriented in the longitudinal direction (LD) and circumferential direction (CD) has never been quantified. In this study, tissue clearing and immunohistochemistry were performed so that the VaSM, and surrounding nerves, within whole rat vaginas ([Formula: see text]) could be imaged without tissue sectioning, preserving the three-dimensional architecture of the organs. Using these methods, the vagina was viewed through the full thickness of the muscularis layer, from the distal to the proximal regions. The VaSM orientation in the proximal and distal regions and the VaSM content along the LD and CD were quantified. Additionally, a qualitative assessment of vaginal nerves was performed. When compared using a permuted version of the Watson [Formula: see text] test, the orientation of VaSM in the proximal and distal regions were found to be significantly different in 4 of the 6 imaged rat vaginas ([Formula: see text]). While the distal vagina contained a similar amount of VaSM oriented within [Formula: see text] of the LD and within [Formula: see text] of the CD, the proximal vagina contained significantly more VaSM oriented towards the LD than towards the CD. Nerve fibers were found to be wavy, running both parallel and perpendicular to vascular and non-vascular smooth muscle within the vagina. Micro-structural analyses, like the one conducted here, are necessary to understand the physiological function and pathological changes of the vagina.

Transcriptome profiling of lncRNA and co-expression network in the vaginal epithelial tissue of women with lubrication disorders

Background

Vaginal lubrication is a crucial physiological response that occurs at the beginning of sexual arousal. However, research on lubrication disorders (LD) is still in its infancy, and the role of long non-coding RNAs (lncRNAs) in LD remains unclear. This study aimed to explore the function of lncRNAs in the pathogenesis of vaginal LD.

Methods

The expression profiles of LD and normal control (NC) lncRNAs were examined using next-generation sequencing (NGS), and eight selected differentially expressed lncRNAs were verified by quantitative real-time PCR. We conducted GO annotation and KEGG pathway enrichment analyses to determine the principal functions of significantly deregulated genes. LncRNA-mRNA co-expression and protein-protein interaction (PPI) networks were constructed and the lncRNA transcription factors (TFs) were predicted.

Results

From the results, we identified 181,631 lncRNAs and 145,224 mRNAs in vaginal epithelial tissue. Subsequently, our preliminary judgment revealed a total of 499 up-regulated and 337 down-regulated lncRNAs in LD. The top three enriched GO items of the dysregulated lncRNAs included the following significant terms: “contractile fiber part,” “actin filament-based process,” and “contractile fiber”. The most enriched pathways were “cell-extracellular matrix interactions,” “muscle contraction,” “cell-cell communication,” and “cGMP-PKG signaling pathway”. Our results also showed that the lncRNA-mRNA co-expression network was a powerful platform for predicting lncRNA functions. We determined the three hub genes, ADCY5, CXCL12, and NMU, using PPI network construction and analysis. A total of 231 TFs were predicted with RHOXF1, SNAI2, ZNF354C and TBX15 were suspected to be involved in the mechanism of LD.

Conclusion

In this study, we constructed the lncRNA-mRNA co-expression network, predicted the lncRNA TFs, and comprehensively analyzed lncRNA expression profiles in LD, providing a basis for future studies on LD clinical biomarkers and therapeutic targets. Further research is also needed to fully determine lncRNA’s role in LD development.

Ultra-deformable liposomes containing terpenes (terpesomes) loaded fenticonazole nitrate for treatment of vaginal candidiasis: Box-Behnken design optimization, comparative ex vivo and in vivo studies

Fenticonazole nitrate (FTN) is a potent antifungal drug adopted in the treatment of vaginal candidiasis. It has inadequate aqueous solubility hence, novel ultra-deformable liposomes 'Terpesomes' (TPs) were developed that might prevail over FTN poor solubility besides TPs might abstain the obstacles of mucus invasion. TPs were assembled by thin-film hydration then optimized by Box Behnken design utilizing terpenes ratio (X₁), sodium deoxycholate amount (X₂), and ethanol concentration (X₃) as independent variable, whereas their impact was inspected for entrapment efficiency (Y₁), particle size (Y₂), and polydispersity index (Y₃). Design Expert^® was bestowed to select the optimal TP for more studies. The optimal TP had entrapment efficiency of 62.18 ± 1.39%, particle size of 310.00 ± 8.16 nm, polydispersity index of 0.20 ± 0.10, and zeta potential of -10.19 ± 0.2.00 mV. Elasticity results were greater in the optimal TP related to classical bilosomes. Further, ex vivo permeation illustrated tremendous permeability from the optimal TP correlated to classical bilosomes, and FTN suspension. Besides, in vivo assessment displayed significant inhibition effect in rats from FTN-TPs gel compared to FTN gel. The antifungal potency with undermost histopathological variation was detected in rats treated with FTN-TPs gel. Overall, the acquired findings verified the potency of utilizing FTN-TPs gel for treatment of vaginal candidiasis.

Estrogen modulates epithelial progenitor cells in rat vagina

Purpose

The expression of epithelial progenitor cells (EPCs) in rat vagina was recently reported. The aims were to investigate the effects of estrogen on vaginal EPCs in the oophorectomized female rat model.

Materials and Methods

Female Sprague-Dawley rats (230–240 g, n=30) were divided into 3 groups: control (n=10), bilateral oophorectomy (OVX, n=10), and bilateral OVX followed by subcutaneous injections of 17β-estradiol (50 µg/kg/day, n=10). After 4 weeks, the expression of EPC-specific markers (CD44, estrogen receptor alpha [ERα], and progesterone receptor) were evaluated by immunohistochemistry and Western blot.

Results

The CD44/ERα double-labeled cells were mainly expressed in basal cell layers and suprabasal layers as shown by confocal immunofluorescence. Confocal microscopy revealed that the number of CD44+/ERα+ cells decreased in the OVX group compared with the controls but was similar to control levels in rats receiving estrogen replacements. The protein expression of CD44 and ERα decreased after OVX and was restored to control levels after estrogen supplementation.

Conclusions

Markers of EPCs were expressed in the vagina, and the expression of resident EPCs was regulated by estrogen. These findings imply that resident EPCs may have an important role in the regeneration of vaginal mucosa by estrogen replacement.

miR-137 Affects Vaginal Lubrication in Female Sexual Dysfunction by Targeting Aquaporin-2

Introduction

Female sexual dysfunction (FSD) is a common disease with serious potential hazards, but it has not received much attention. The pathogenesis of FSD is urgently needed for the diagnosis and treatment of FSD.

Aim

To investigate the role of microribonucleic acid (mRNA, miR)-137 in FSD.

Methods

Vaginal epithelium tissues from 15 women with lubrication disorder and 15 women with normal function were collected for this study. The expression level of miR-137 in lubrication disorder and normal function women were measured by microarray analysis and Real-time Quantitative Polymerase Chain Reaction (PCR, qPCR). miR-137 was overexpressed in vaginal epithelial cells VK2/E6E7 by lentivirus infection. The cell water permeability was measured using the calcein-quenching method. Cell apoptosis was analyzed by flow cytometry. The potential target of miR-137 was predicted by bioinformatic analysis, then verified by luciferase reporter assays.

Main Outcome Measure

The expression level of miR-137 and aquaporin-2 (AQP2), cell water permeability, cell apoptosis, and luciferase reporter assays were examined.

Results

miR-137 was found to be highly expressed in vaginal epithelial tissues of women with lubrication disorder. Additionally, functional in vitro studies suggested that overexpression of miR-137 leads to a decrease in cell permeability. By combining target prediction and examination, we identified AQP2 as the direct mechanistic target of miR-137 that affected the water permeability of vaginal epithelial cells.

Conclusion

Our results point to a novel role for miR-137 and its downstream effector AQP2 in vaginal lubrication, which can be manipulated as therapeutic targets against lubrication disorder and its related disorders.

Zhang H, Liu T, Zhou Z. miR-137 affects vaginal lubrication in female sexual dysfunction by targeting Aquaporin-2. Sex Med 2018;6:339–347.

Identification and localization of epithelial progenitor cells in the vagina

The purpose of this study was to identify and localize mucosal epithelial progenitor cells (EPCs) in the rat vagina. Rat vagina was obtained from f77emale Sprague-Dawley rats (12 weeks old, n = 20). To identify EPCs in vagina, we followed a single-cell isolation protocol and analyzed the number of cells staining positive for EPC markers by flow cytometry. The expression of EPC-specific markers (CD44, ERα, PR) was evaluated by immunofluorescence. As shown by confocal immunofluorescence, CD44/ERα double-labeled cells were mainly expressed in the basal cell and suprabasal cell layers. Immunofluorescent staining of CD44 was expressed in the plasma membrane of the vaginal epithelium, and ERα was expressed in the cytoplasm of the vaginal epithelium. The CD44/ERα double-positive cells were noted in the rat vagina by flow cytometric analysis. PR-labeled cells were localized in the intermediate layer of the epithelial space of the vagina. The results revealed the existence of EPCs in the vagina. These findings imply that resident EPCs may have a role in the regeneration of vaginal mucosa.

All-Trans Retinoic Acid Increases Aquaporin 3 Expression in Human Vaginal Epithelial Cells

Introduction

Water channel aquaporin 3 (AQP3) is an aquaglyceroporin that transports small neutral solutes and water. All-trans retinoic acid (ATRA), a member of the retinoid drug class, acts as a regulator in several biological processes.

Aim

To investigate the effect of ATRA on the expression of AQP3 in human vaginal epithelial cells.

Methods

Human vaginal mucosal epithelial cells (CRL2616) were treated with ATRA 0, 0.01, 0.1, and 1 μmol/L for 24 hours to examine the dose-dependent effects of ATRA and with ATRA 1 μmol/L for 0, 3, 6, 12, and 24 hours.

Main Outcome Measures

The expression of AQP3 and retinoic acid receptor (RAR) was determined by western blot analysis and reverse transcription polymerase chain reaction.

Results

AQP3 was detected in the cell membrane of human vaginal epithelial cells. ATRA increased the protein expression and mRNA levels of AQP3 in a dose-dependent manner (P < .05). ATRA also increased the protein expression of RARα (P < .05). Treatment of CRL2616 cells with an RAR antagonist (Ro 41-5253) significantly decreased AQP3 protein expression (P < .05).

Conclusion

ATRA mediated by RARα increased AQP3 gene and protein expression in human vaginal mucosal epithelial cells. These results imply that AQP3 regulated by ATRA could play an important role in the mechanism of vaginal lubrication.

Estrogen Modulates Expression of Tight Junction Proteins in Rat Vagina

Background. The objectives of this study were to investigate the localization of tight junctions and the modulation of zonula occludens- (ZO-) 1, occludin and claudin-1 expression by estrogen in castrated female rat vagina. Female Sprague-Dawley rats (230–240 g, n = 45) were divided into three groups and subjected to a sham operation (control group, n = 15), bilateral ovariectomy (Ovx group, n = 15), or bilateral ovariectomy followed by daily subcutaneous injection of 17β-estradiol (50 μg/kg/day, Ovx + Est group, n = 15). The cellular localization and expression of ZO-1, occludin, and claudin-1 were determined in each group by immunohistochemistry and western blot. Results. Expression of ZO-1 was diffuse in all groups, with the highest intensity in the superficial epithelium in the control group. Occludin was localized in the intermediate and basal epithelium. Claudin-1 was most intense in the superficial layer of the vaginal epithelium in the control group. Expression of ZO-1, occludin, and claudin-1 was significantly decreased after ovariectomy and was restored to the level of the control after estrogen replacement. Conclusions. Tight junctions are distinctly localized in rat vagina, and estrogen modulates the expression of tight junctions. Further researches are needed to clarify the functional role of tight junctions in vaginal lubrication.

Expression of aquaporin proteins in vagina of diabetes mellitus rats

INTRODUCTION

Aquaporins (AQPs) are membrane proteins that facilitate water movement across biological membranes. Vaginal lubrication may be mediated by blood flow and other potential mechanisms related to transudation of fluid. The most common female sexual dysfunction in diabetes is inadequate vaginal lubrication.

AIM

To investigate the expression of AQP1-3 in vaginal tissue of diabetes mellitus rats.

METHODS

Female Sprague-Dawley rats (N = 20) were randomly divided into group A (12-week-old nondiabetic control, N = 5), group B (16-week-old nondiabetes control, N = 5), group C (12-week-old diabetes mellitus rats, N = 5), and group D (16-week-old diabetes mellitus rats, N = 5). Vaginal fluid was measured by fluid weight absorbed by cotton swabs after pelvic nerve electrostimulation and anterior vaginal tissue was dissected for determining the expression of AQP1-3 by immunohistochemical study and Western blot.

MAIN OUTCOME MEASURES

The expression of AQP1-3 was determined in the vagina of diabetes mellitus rats by Western blot.

RESULTS

There are no significant differences in serum estradiol concentrations of rats among these groups (P > 0.05). Vaginal fluid was significantly lower in group C (2.7 ± 0.67 mg) and group D (2.5 ± 1.03 mg) than in group A (5.74 ± 1.23 mg) and group B (5.5 ± 1.08 mg) (P < 0.05), respectively. The protein expressions of AQP1-3 were significantly lower in group C (43.40 ± 4.83, 60.60 ± 12.80, and 59.60 ± 6.95) and group D (20.81 ± 2.86, 47.80 ± 11.43, and 54.20 ± 5.26) than in group A (116.62 ± 3.21, 110.81 ± 8.044, and 108.80 ± 4.97) and group B (122.12 ± 14.54, 111.21 ± 15.07, and 106.40 ± 4.16) (P < 0.05), respectively.

CONCLUSIONS

Decreased vaginal fluid in diabetes mellitus rats after electrostimulation may be partly due to estrogen-independent decreases of AQP1-3 in vaginal tissue.

Neurologic factors in female sexual function and dysfunction

Sexual dysfunction affects both men and women, involving organic disorders, psychological problems, or both. Overall, the state of our knowledge is less advanced regarding female sexual physiology in comparison with male sexual function. Female sexual dysfunction has received little clinical and basic research attention and remains a largely untapped field in medicine. The epidemiology of female sexual dysfunction is poorly understood because relatively few studies have been done in community settings. In the United States, female sexual dysfunction has been estimated to affect 40% of women in the general population. Among the elderly, however, it has been reported that up to 87% of women complain of sexual dissatisfaction. Several studies have shown that the prevalence of female sexual arousal disorders correlates significantly with increasing age. These studies have shown that sexual arousal and frequency of coitus in the female decreases with increasing age. The pathophysiology of female sexual dysfunction appears more complex than that of males, involving multidimensional hormonal, neurological, vascular, psychological, and interpersonal aspects. Organic female sexual disorders may include a wide variety of vascular, neural, or neurovascular factors that lead to problems with libido, lubrication, and orgasm. However, the precise etiology and mechanistic pathways of age-related female sexual arousal disorders are yet to be determined. In the past two decades, some advances have been made in exploring the basic hemodynamics and neuroregulation of female sexual function and dysfunction in both animal models and in human studies. In this review, we summarize neural regulation of sexual function and neurological causes of sexual dysfunction in women.

The effect of Korean red ginseng extract on the relaxation response in isolated rabbit vaginal tissue and its mechanism

INTRODUCTION

Ginseng is an herbal medicine with a variety of biological activities.

AIM

The purpose of this study was to investigate the effect of Korean red ginseng (KRG) extract on the relaxation response in isolated rabbit vaginal tissue and its mechanism as a potential therapeutic agent for female sexual dysfunction.

METHOD

Strips of rabbit vagina were mounted in organ chambers to measure isometric tension. After the strips were precontracted with phenylephrine, the contractile responses to KRG extract (1-20 mg/mL), nitric oxide inhibitor (N[omega]-nitro-L-arginine methyl ester [L-NAME]), an inhibitor of soluble guanylate cyclase (methylene blue), an inhibitor of Ca(2+)-activated K(+) channels (tetraethylammonium [TEA]), and an adenosine triphosphate (ATP)-sensitive K(+) channel blocker (glybenclamide) were examined.

MAIN OUTCOME MEASURES

The relaxation of the vaginal tissue strip was assessed after treating KRG extract or other chemicals.

RESULTS

KRG (1-20 mg/mL) extract relaxed the vaginal tissue strip in a dose-dependent manner up to 85%. The relaxation effect was significantly inhibited by L-NAME (30 microM) and methylene blue (30 microM) (P < 0.05). In addition, KRG inhibited the contraction induced by depolarization with 10, 20, and 40 mM KCl. The KRG-induced relaxation effect was significantly inhibited by TEA (300 microM) (P < 0.05), and not by glybenclamide (30 microM).

CONCLUSIONS

These data show that KRG extract has a relaxing effect on rabbit vaginal smooth muscle tissue. These effects might be mediated partly through the NO pathway and hyperpolarization via Ca(2+)-activated K(+) channels.

Vaginal physiological changes in a model of sexual arousal in anesthetized rats

The understanding of the pathophysiology of female sexual dysfunction suffers from the lack of a convenient model for the study of female genital sexual response. In this study, systemic arterial blood pressure (BP) as well as partial oxygen tension, temperature, and blood engorgement of the vagina [using laser-Doppler flowmetry in arbitrary units (AU)] were measured in anesthetized, ovariectomized (1 wk before the start of the experiment) female rats. Vaginal sexual arousal was replicated by electrical stimulation of the pelvic nerve (PNS). PNS induced reproducible increases in the different vaginal parameters (from baseline value, respectively: 16 +/- 10 to 30 +/- 12 mmHg; 34.9 +/- 0.6 to 36 +/- 0.6 degrees C; 450 +/- 196 to 1,500 +/- 360 AU; P < 0.05, paired t-test) and BP (90 +/- 7 to 123 +/- 13 mmHg, P < 0.05, paired t-test). Vaginal vascular resistance was significantly decreased during PNS (from 0.23 +/- 0.15 to 0.08 +/- 0.02 mmHg/AU). Vaginal wall tension was also measured with a force transducer. PNS induced an increase in vaginal wall tension (1.0 +/- 0.2 g), followed by a decrease under the prestimulation value. Intravenous atropine sulfate (1 mg/kg) injection abolished the increase in vaginal wall tension without significantly affecting vaginal vascular resistance. Intravenous vercuronium bromide (2 mg/kg) injection abolished the decrease in vaginal wall tension. Concomitant electrical stimulation of the paravertebral sympathetic chain inhibited vaginal response induced by PNS. Electrical stimulation of the medial preoptic area of the hypothalamus induced a response qualitatively equivalent to PNS with a significant decrease of vaginal vascular resistance. These data support that vaginal contractions involve both smooth and striated muscles and indicate that neural control of vaginal sexual arousal have great similarities in male and female rats.