Regulation of the immunoexpression of aquaporin 9 by ovarian hormones in the rat oviductal epithelium

Targeting Aquaporin-5 by Phosphodiesterase 4 Inhibition Offers New Therapeutic Opportunities for Ovarian Ischemia Reperfusion Injury in Rats

This study aimed to examine the effect of Phosphodiesterase 4 (PDE4) inhibition on Aquaporin-5 (AQP5) and its potential cell signaling pathway in the ovarian ischemia reperfusion (OIR) model. Thirty adult female rats were divided into five groups: Group 1; Control: Sham operation, Group 2; OIR that 3 hour ischemia followed by 3 hour reperfusion, Group 3; OIR + Rolipram 1 mg/kg, Group 4; OIR + Rolipram 3 mg/kg, Group 5; OIR + Rolipram 5 mg/kg. Rolipram was administered intraperitoneally to the rats in groups 3-4 and 5 at determined doses 30 minutes before reperfusion. From ovary tissue; Tumor necrosis factor-a (TNF-α), Cyclic adenosine monophosphate (cAMP), Nuclear factor kappa (NF-κB), Interleukin-6 (IL-6), Phosphodiesterase 4D (PDE4D), Mitogen-activated protein kinase (MAPK) and AQP5 levels were measured by ELISA. We also measured the level of AQP5 in ovary tissue by real-time reverse-transcription polymerase chain reaction (RT-PCR). In the OIR groups; TNF-α, NF-κB, IL-6, MAPK inflammatory levels increased, and cAMP and AQP5 levels decreased, which improved with the administration of rolipram doses. Also histopathological results showed damaged ovarian tissue after OIR, while rolipram administration decrased tissue damage in a dose dependent manner. We propose that the protective effect of PDE4 inhibition in OIR may be regulated by AQP5 and its potential cell signaling pathway and may be a new target in OIR therapy. However, clinical studies are needed to appraise these data in humans.

Expression of genes for transport of water and angiogenesis, as well as biochemical biomarkers in Holstein dairy cows during the ovsynch program

Changes in expression of genes associated with angiogenesis and transport of water by cells, as well as biomarkers of oxidative stress were determined at specific times during the ovsynch protocol to synchronize estrus and breed Holstein dairy cows. Blood samples were taken from 82 lactating Holstein cows at the time of the 1st GnRH injection (G1), 7 days later at the time of the PGF2a (PG) injection, and 48 h after the PGF2a treatment when the second injection of GnRH was administered (G2). The serum was analyzed for malondialdehyde (MDA), reduced glutathione (GSH), glutathione peroxidase (GPX), nitric oxide (NO), catalase (CAT), and total antioxidant capacity (TAC). The expression of vascular endothelial growth factor (VEGF), vascular endothelial growth factor receptor 2 (VEGFR2), endothelial nitric oxide synthase (eNOS3), aquaporin 3 (AQP3), and AQP4 mRNAs in peripheral blood mononuclear cells (PBMCs) was analyzed. The number of copies of each of the mRNAs was quantified using qPCR. Pregnancy status was determining at 32 ± 3 days after insemination using an ultrasound "Sonoscape-5V″ model. Receiver operating curves (ROC) were used to assess the sensitivity and specificity of the biochemical parameters in serum to predict establishment of p The expression of MDA, GPX, and Catalase changed (P < 0·05) between G1, PG and G2 phases of the ovsynch protocol with higher levels at PG than at G1 and G2. The highest levels of NO were detected at G2. The ROC analyses identified NO, TAC and CAT as the most sensitive and specific biomarker for pregnancy with areas under the curve being 0.875 (P < 0.0001), 0.843 (P < 0.03), 0.833 (P < 0.017), sensitivity being 75.3, 42.86, and 26.27%, and specificity being 90, 90 and 85% respectively. The expression for VEGF, VEGFR2, eNOS3, AQP3, and AQP4 mRNAs was upregulated at PG compared to G1 and G2 phases of the ovsynch protocol. The results suggest that following the first injection of GnRH, there is an increase in expression of VEGF, VEGFR2, eNOS3, AQP3, and AQP4 mRNAs by the time of the PGF2a injection and then expression decreased. Further, ROC analyses identified increases in NO, TAC and CAT as the most sensitive and specific biomarkers with the greatest potential to predict establishment of pregnancy in Holstein cows.

Integrated microRNA and secretome analysis of human endometrial organoids reveal the miR-3194-5p/Aquaporin/S100A9 module in regulating trophoblast functions

Successful placentation requires delicate communication between the endometrium and trophoblasts. The invasion and integration of trophoblasts into the endometrium during early pregnancy is crucial to placentation. Dysregulation of these functions is associated with various pregnancy complications, such as miscarriage and preeclampsia. The endometrial microenvironment has an important influence on trophoblast cell functions. The precise effect of the endometrial gland secretome on trophoblast functions remains uncertain. We hypothesized that the hormonal environment regulates the miRNA profile and secretome of the human endometrial gland, which subsequently modulates trophoblast functions during early pregnancy. Human endometrial tissues were obtained from endometrial biopsies with written consent. Endometrial organoids were established in matrix gel under defined culture conditions. They were treated with hormones mimicking the environment of the proliferative phase (Estrogen, E2), secretory phase (E2+Progesterone, P4), and early pregnancy (E2+P4+Human Chorionic Gonadotropin, hCG). miRNA-seq was performed on the treated organoids. Organoid secretions were also collected for mass spectrometric analysis. The viability and invasion/migration of the trophoblasts after treatment with the organoid secretome were determined by cytotoxicity assay and transwell assay, respectively. Endometrial organoids with the ability to respond to sex steroid hormones were successfully developed from human endometrial glands. By establishing the first secretome profiles and miRNA atlas of these endometrial organoids to the hormonal changes followed by trophoblast functional assays, we demonstrated that sex steroid hormones modulate aquaporin (AQP)1/9 and S100A9 secretions through miR-3194 activation in endometrial epithelial cells, which in turn enhanced trophoblast migration and invasion during early pregnancy. By using a human endometrial organoid model, we demonstrated for the first time that the hormonal regulation of the endometrial gland secretome is crucial to regulating the functions of human trophoblasts during early pregnancy. The study provides the basis for understanding the regulation of early placental development in humans.

Importance of Water Transport in Mammalian Female Reproductive Tract

Aquaporins (AQPs) are involved in water homeostasis in tissues and are ubiquitous in the reproductive tract. AQPs are classified into classical aquaporins (AQP0, 1, 2, 4, 5, 6 and 8), aquaglycerolporins (AQP3, 7, 9, and 10) and superaquaporins (AQP11 and 12). Nine AQPs were described in the mammalian female reproductive tract. Some of their functions are influenced by sexual steroid hormones. The continuous physiological changes that occur throughout the sexual cycle, pregnancy and parturition, modify the expression of AQPs, thus creating at every moment the required water homeostasis. AQPs in the ovary regulate follicular development and ovulation. In the vagina and the cervix, AQPs are involved mainly in lubrication. In the uterus, AQPs are mostly mediated by estradiol and progesterone to prepare the endometrium for possible embryo implantation and fetal development. In the placenta, AQPs are responsible for the fluid support to the fetus to maintain fetal homeostasis that ensures correct fetal development as pregnancy goes on. This review is focused on understanding the role of AQPs in the mammalian female reproductive tract during the sexual cycle of pregnancy and parturition.

Aquaporins in Reproductive System

AQP0-12, a total of 13 aquaporins are expressed in the mammalian reproductive system. These aquaporins mediate the transport of water and small solutes across biofilms for maintaining reproductive tract water balance and germ cell water homeostasis. These aquaporins play important roles in the regulation of sperm and egg cell production, maturation, and fertilization processes. Impaired AQP function may lead to diminished male and female fertility. This review focuses on the distribution, function, and regulation of AQPs throughout the male and female reproductive organs and tracts. Their correlation with reproductive success, revealing recent advances in the physiological and pathophysiological roles of aquaporins in the reproductive system.

Modification of Morphology and Glycan Pattern of the Oviductal Epithelium of Baboon Papio hamadryas during the Menstrual Cycle

The mammalian oviduct is a highly specialized structure where fertilization and early embryonic development occur. Its mucosal epithelium is involved in maintaining and modulating a dynamic intraluminal fluid. The oviductal epithelium consists of ciliated and non-ciliated (secretory) cells whose differentiation and activity are sex hormone-dependent. In this study, we investigated for the first time both the morphology and the glycan composition of baboon oviductal epithelium during the menstrual cycle. Oviducts were laparoscopically removed from 14 healthy adult female Papio hamadryas whose menstrual cycle phase was assessed based on the sex hormone levels and the vaginal cytology features. Histological investigations were carried out on fimbriae, infundibulum, ampulla, and isthmus separately fixed in 4% (v/v) paraformaldehyde, embedded in paraffin wax, and stained with hematoxylin-eosin for morphological analyses and using a panel of nine fluorescent lectins for glycoconjugate characterization. The histomorphological analysis revealed that in the entire oviduct (i) the ciliated and non-ciliated cells were indistinguishable during the follicular and luteal phases, whereas they were highly differentiated during the preovulatory phase when the non-ciliated cells exhibited apical protrusions, (ii) the epithelium height was significantly higher in the preovulatory phase compared to other menstrual phases, and (iii) the number of ciliated cells significantly (p ≤ 0.05) increased from the fimbriae to the infundibulum and progressively reduced in the other oviductal segments with the lower presence of ciliated cells in the isthmus. The glycan characterization revealed a complex and region-specific composition during the different phases of the menstrual cycle. It can be summarized as follows: (i) high-mannosylated N-linked glycans (Con A reactivity) were present throughout the oviductal epithelium during the entire menstrual cycle and characteristically in the apical protrusions of non-ciliated cells of the ampulla during the preovulatory phase; (ii) sialoglycans with α2,3-linked sialic acids (MAL II binding) were expressed along the entire oviductal surface only during the preovulatory phase, whereas α2,6-linked ones (SNA affinity) were also detected in the surface of the luteal phase, although during the preovulatory phase they were characteristically found in the glycocalyx of the isthmus cilia, and O-linked sialoglycans with sialic acids linked to Galβl,3GalNAc (T antigen) (KsPNA) and terminal N-acetylgalactosamine (Tn antigen) (KsSBA) were found in the entire oviductal surface during all phases of the menstrual cycle; (iii) GalNAc terminating O-linked glycans (HPA staining) were mainly expressed in the entire oviducts of the luteal and preovulatory phases, and characteristically in the apical protrusions of the isthmus non-ciliated cells of the preovulatory phase; and (iv) fucosylated glycans with α1,2-linked fucose (LTA reactivity) occurred in the apical surface of fimbriae during the luteal phase, whereas α1,3/4-linked fucose (UEA I binders) were present in the apical protrusions of the ampulla non-ciliated cells and in the apical surface of isthmus during the preovulatory phase as well as in the isthmus apical surface of follicular-phase oviducts. These results demonstrate for the first time that morphological and glycan changes occur in the baboon oviductal epithelium during the menstrual cycle. Particularly, the sex hormone fluctuation affects the glycan pattern in a region-specific manner, probably related to the function of the oviductal segments. The findings add new data concerning baboons which, due to their anatomical similarity to humans, make an excellent model for female reproduction studies.

The Multifaceted Role of Aquaporin-9 in Health and Its Potential as a Clinical Biomarker

Aquaporins (AQPs) are transmembrane channels essential for water, energy, and redox homeostasis, with proven involvement in a variety of pathophysiological conditions such as edema, glaucoma, nephrogenic diabetes insipidus, oxidative stress, sepsis, cancer, and metabolic dysfunctions. The 13 AQPs present in humans are widely distributed in all body districts, drawing cell lineage-specific expression patterns closely related to cell native functions. Compelling evidence indicates that AQPs are proteins with great potential as biomarkers and targets for therapeutic intervention. Aquaporin-9 (AQP9) is the most expressed in the liver, with implications in general metabolic and redox balance due to its aquaglyceroporin and peroxiporin activities, facilitating glycerol and hydrogen peroxide (H₂O₂) diffusion across membranes. AQP9 is also expressed in other tissues, and their altered expression is described in several human diseases, such as liver injury, inflammation, cancer, infertility, and immune disorders. The present review compiles the current knowledge of AQP9 implication in diseases and highlights its potential as a new biomarker for diagnosis and prognosis in clinical medicine.

Nutritional and Physiological Regulation of Water Transport in the Conceptus

Water transport during pregnancy is essential for maintaining normal growth and development of conceptuses (embryo/fetus and associated membranes). Aquaporins (AQPs) are a family of small integral plasma membrane proteins that primarily transport water across the plasma membrane. At least 11 isoforms of AQPs (AQPs 1-9, 11, and 12) are differentially expressed in the mammalian placenta (amnion, allantois, and chorion), and organs (kidney, lung, brain, heart, and skin) of embryos/fetuses during prenatal development. Available evidence suggests that the presence of AQPs in the conceptus mediates water movement across the placenta to support the placentation, the homeostasis of amniotic and allantoic fluid volumes, as well as embryonic and fetal survival, growth and development. Abundances of AQPs in the conceptus can be modulated by nutritional status and physiological factors affecting the pregnant female. Here, we summarize the effects of maternal dietary factors (such as intakes of protein, arginine, lipids, all-trans retinoic acid, copper, zinc, and mercury) on the expression of AQPs in the conceptus. We also discuss the physiological changes in hormones (e.g., progesterone and estrogen), oxygen supply, nitric oxide, pH, and osmotic pressure associated with the regulation of fluid exchange between mother and fetus. These findings may help to improve the survival, growth, and development of embryo/fetus in livestock species and other mammals (including humans).

Spatiotemporal expression of aquaporin 9 is critical for the antral growth of mouse ovarian follicles†

Although a few aquaporins (AQPs) expressed in granulosa cells have been postulated to mediate fluid passage into the antrum, the specific expression of AQPs in different follicle cell types and stages and their roles have not been evaluated extensively. The spatiotemporal expression of aquaporin (Aqp) 7, 8, and 9 and the functional roles of Aqp9 in antral growth and ovulation were examined using a superovulation model and 3-dimensional follicle culture. Aqp9 was expressed at a high level in the rapid growth phase (24-48 h post equine chorionic gonadotropin (eCG) for superovulation induction) compared to Aqp7 (after human chorionic gonadotropin (hCG)) and Aqp8 (8-24 h post eCG and 24 h post hCG). A dramatic increase in the expression and localization of Aqp9 mRNA in theca cells was observed, as evaluated using quantitative reverse transcription-polymerase (RT-PCR) coupled with laser capture microdissection and immunohistochemistry. AQP9 was located primarily on the theca cells of the tertiary and preovulatory follicles but not on the ovulated follicles. In phloretin-treated mice, the diameter of the preovulatory follicles and the number of ovulated oocytes decreased. Consistent with these findings, knocking down Aqp9 expression with an Aqp9 siRNA inhibited follicle growth (0.28:1 = siRNA:control) and decreased the number of ovulated follicles (0.36:1 = siRNA:control) during in vitro growth and ovulation induction. Based on these results, the expression of AQPs is under the control of the physiological status, and AQP9 expression in theca during folliculogenesis is required for antral growth and ovulation in a tissue-specific and stage-dependent manner.

Aquaporins and (in)fertility: More than just water transport

Aquaporins (AQPs) are a family of channel proteins that facilitate the transport of water and small solutes across biological membranes. They are widely distributed throughout the organism, having a number of key functions, some of them unexpected, both in health and disease. Among the various diseases in which AQPs are involved, infertility has been overlooked. According to the World Health Organization (WHO) infertility is a global public health problem with one third of the couples suffering from subfertility or even infertility due to male or female factors alone or combined. Thus, there is an urgent need to unveil the molecular mechanisms that control gametes production, maturation and fertilization-related events, to more specifically determine infertility causes. In addition, as more couples seek for fertility treatment through assisted reproductive technologies (ART), it is pivotal to understand how these techniques can be improved. AQPs are heterogeneously expressed throughout the male and female reproductive tracts, highlighting a possible regulatory role for these proteins in conception. In fact, their function, far beyond water transport, highlights potential intervention points to enhance ART. In this review we discuss AQPs distribution and structural organization, functions, and modulation throughout the male and female reproductive tracts and their relevance to the reproductive success. We also highlight the most recent advances and research trends regarding how the different AQPs are involved and regulated in specific mechanisms underlying (in)fertility. Finally, we discuss the involvement of AQPs in ART-related processes and how their handling can lead to improvement of infertility treatment.

The Relevance of Aquaporins for the Physiology, Pathology, and Aging of the Female Reproductive System in Mammals

Aquaporins constitute a group of water channel proteins located in numerous cell types. These are pore-forming transmembrane proteins, which mediate the specific passage of water molecules through membranes. It is well-known that water homeostasis plays a crucial role in different reproductive processes, e.g., oocyte transport, hormonal secretion, completion of successful fertilization, blastocyst formation, pregnancy, and birth. Further, aquaporins are involved in the process of spermatogenesis, and they have been reported to be involved during the storage of spermatozoa. It is noteworthy that aquaporins are relevant for the physiological function of specific parts in the female reproductive system, which will be presented in detail in the first section of this review. Moreover, they are relevant in different pathologies in the female reproductive system. The contribution of aquaporins in selected reproductive disorders and aging will be summarized in the second section of this review, followed by a section dedicated to aquaporin-related proteins. Since the relevance of aquaporins for the male reproductive system has been reviewed several times in the recent past, this review aims to provide an update on the distribution and impact of aquaporins only in the female reproductive system. Therefore, this paper seeks to determine the physiological and patho-physiological relevance of aquaporins on female reproduction, and female reproductive aging.

Expression and Regulation of Aquaporins in Pregnancy Complications and Reproductive Dysfunctions

Aquaporins (AQPs), small hydrophobic integral membrane proteins, mediate rapid transport of water and small solutes. The abnormal expressions of AQPs are associated with pregnancy complications and reproductive dysfunctions, including preeclampsia, gestational diabetes mellitus, tubal ectopic pregnancy, intrahepatic cholestasis of pregnancy, preterm birth, chorioamnionitis, polyhydramnios, and oligohydramnios, thus resulting in adverse pregnancy outcomes. This review explains the alterations of AQPs in pregnancy complications and reproductive dysfunctions and summarizes the molecular mechanisms involved in the regulations of AQPs by drugs such as oxytocin, polychlorinated biphenyls, all-trans-retinoic acid, salvia miltiorrhiza, and insulin, or other factors such as oxygen and osmotic pressure. All the research provides evidence that AQPs could be the new therapeutic targets of pregnancy-related diseases.

Changes in Aquaporin 1, 5 and 9 Gene Expression in the Porcine Oviduct According to Estrous Cycle and Early Pregnancy

Aquaporins (AQPs) are a group of small, integral membrane proteins which play an important role in fluid homeostasis in the reproductive system. In our previous study, we demonstrated AQP1, 5 and 9 protein expression and localization in the porcine oviduct. The presence of these isoforms could suggest their role in the transport of the ovum to the uterus by influencing the epithelial cells’ production of oviductal fluid. The aim of this study was to evaluate the expression of AQP1, AQP5 and AQP9 in the infundibulum, ampulla and isthmus in the porcine oviduct during the estrous cycle (early luteal phase, days 2–4, medium luteal phase, days 10–12, late luteal phase days 14–16, follicular phase days 18–20) and pregnancy (period before implantation, days 14–16 and after the implantation, days 30–32) using the Real-Time PCR technique. As clearly demonstrated for the first time, AQP1, 5, and 9 gene expression is influenced by the estrus cycle and pregnancy. Furthermore, expression of AQPs in the porcine oviduct may provide the physiological medium that sustains and enhances fertilization and early cleavage-stage embryonic development. Overall, our study provides a characterization of oviduct AQPs, increasing our understanding of fluid homeostasis in the porcine oviduct to successfully establish and maintain pregnancy.

Transcriptome analysis during photostimulated recrudescence reveals distinct patterns of gene regulation in Siberian hamster ovaries†

In Siberian hamsters, exposure to short days (SDs, 8 h light:16 h dark) reduces reproductive function centrally by decreasing gonadotropin secretion, whereas subsequent transfer of photoinhibited hamsters to stimulatory long days (LDs, 16 L:8 D) promotes follicle stimulating hormone (FSH) release inducing ovarian recrudescence. Although differences between SD and LD ovaries have been investigated, a systematic investigation of the ovarian transcriptome across photoperiod groups to identify potentially novel factors that contribute to photostimulated restoration of ovarian function had not been conducted. Hamsters were assigned to one of four photoperiod groups: LD to maintain ovarian cyclicity, SD to induce ovarian regression, or post transfer (PT), where females housed in SD for 14-weeks were transferred to LD for 2-days or 1-week to reflect photostimulated ovaries prior to (PTd2) and following (PTw1) the return of systemic FSH. Ovarian RNA was extracted to create RNA-sequencing libraries and short-read sequencing Illumina assays that mapped and quantified the ovarian transcriptomes (n = 4/group). Ovarian and uterine masses, plasma FSH, and numbers of antral follicles and corpora lutea decreased in SD as compared to LD ovaries (P < 0.05). When reads were aligned to the mouse genome, 18 548 genes were sufficiently quantified. Most of the differentially expressed genes noted between functional LD ovaries and regressed SD ovaries; however, five main expression patterns were identified across photoperiod groups. These results, generally corroborated by select protein immunostaining, provide a map of photoregulated ovary function and identify novel genes that may contribute to the photostimulated resumption of ovarian activity.

Oviduct: roles in fertilization and early embryo development

Animal oviducts and human Fallopian tubes are a part of the female reproductive tract that hosts fertilization and pre-implantation development of the embryo. With an increasing understanding of roles of the oviduct at the cellular and molecular levels, current research signifies the importance of the oviduct on naturally conceived fertilization and pre-implantation embryo development. This review highlights the physiological conditions within the oviduct during fertilization, environmental regulation, oviductal fluid composition and its role in protecting embryos and supplying nutrients. Finally, the review compares different aspects of naturally occurring fertilization and assisted reproductive technology (ART)-achieved fertilization and embryo development, giving insight into potential areas for improvement in this technology.

Ultrasound-guided aspiration of hydrosalpinx occurring during controlled ovarian hyperstimulation could improve clinical outcome of in vitro fertilization-embryo transfer

AIM

To investigate whether aspiration of hydrosalpinx during oocyte retrieval could improve the clinical outcome of in vitro fertilization-embryo transfer (IVF-ET).

METHODS

The clinical data of 598 IVF-ET cycles with tubal factor infertility at Reproductive Medical Center, 105 Hospital of People's Liberation Army, Anhui, China, between March 2011 and July 2015 were analyzed in this retrospective study. Among them, 71 cycles with unilateral or bilateral hydrosalpinx confirmed on both hysterosalpingography (HSG) and ultrasonography before controlled ovarian hyperstimulation (COH) were assigned to group A. A total of 51 cycles with unilateral or bilateral hydrosalpinx occurring during COH and confirmed on ultrasonography were assigned to group B. In both group A and group B, ultrasound-guided hydrosalpinx aspiration was performed in all patients when oocyte retrieval was finished. A further 35 cycles with unilateral or bilateral hydrosalpinx during COH received no intervention and were assigned to group C. A total of 441 cycles without hydrosalpinx on HSG or on ultrasonography before or during COH served as the control (group D). The IVF-ET outcomes of the four groups were analyzed and compared.

RESULTS

The embryo implantation rate and clinical pregnancy rate in group A and group C were significantly lower than those in group B and group D. The ongoing pregnancy rate in group A was significantly lower than that in group B and group D, and the ongoing pregnancy rate in group C was significantly lower than that in group D.

CONCLUSION

Aspiration of hydrosalpinx occurring during COH could significantly improve the clinical outcomes of IVF-ET, but not for the hydrosalpinx occurring before COH.

Aquaporin 3 is regulated by estrogen in the chicken oviduct and is involved in progression of epithelial cell-derived ovarian carcinomas

Aquaporins (AQPs) are membrane proteins that passively deliver water across the plasma membrane to play an important role in maintaining cell shape. Members of the AQP family are distributed in most of the tissues in the human body and perform a variety of functions based on the water homeostasis suitable for each organ. However, there is little known about the expression and regulation of AQP family members in chickens. Therefore, we determined the expression of AQPs in various tissues of chickens. Among 13 isotypes, AQP3 was highly expressed in the chicken oviduct. Expression of AQP3 messenger RNA (mRNA) increased in the magnum (P < 0.001) and isthmus (P < 0.001) of chick oviducts treated with diethylstilbestrol. Consistent with these results, the localization of AQP3 was detected in the glandular and luminal epithelia of the magnum and isthmus of oviducts of diethylstilbestrol-treated chicks. In addition, the pattern of expression of AQP3 changed in an estrogen-dependent manner during the molting period. During the regenerative period of the oviduct after molting, expression of AQP3 mRNA increased coordinately with increasing concentrations of estradiol (P < 0.001), whereas expression of AQP3 mRNA decreased as concentrations of estradiol in plasma decreased in response to induced molting (P < 0.001). Also, expression of the AQP3 increased (P < 0.001) in cancerous ovaries of laying hens. In conclusion, AQP3 does not simply function to transport water into and out of cells but also appears to be closely involved in development of the chicken oviduct, which is regulated by estrogens. Furthermore, our results suggest AQP3 as a new diagnostic for early detection and treatment of epithelial cell-derived ovarian carcinomas.

Morphology and Aquaporin Immunohistochemistry of the Uterine Tube of Saanen Goats (Capra hircus): Comparison Throughout the Reproductive Cycle

The expression of six different aquaporins (AQP1, 2, 3, 4, 5 and 9), integral membrane water channels that facilitate bi-directional passive movement of water, was investigated by immunohistochemistry in the uterine tube of pre-pubertal and adult Saanen goats (Capra hircus), comparing the different phases of the oestrous cycle. Regional morphology and secretory processes were markedly different during the goat oestrous cycle. The tested AQP molecules showed different expression patterns in comparison with already studied species. AQP1-immunoreactivity was evidenced at the endothelium of blood vessels and in nerve fibres, regardless of the tubal tract and cycle period. AQP4-immunoreactivity was shown on the lateral plasmalemma in the basal third of the epithelial cells at infundibulum and ampulla level in the cycling goats, more evidently during follicular than during luteal phase. No AQP4-immunoreactivity was noticed at the level of the isthmus region, regardless of the cycle phase. AQP5-immunoreactivity, localized at the apical surface of epithelial cells, increased from pre-puberty to adulthood. Thereafter, AQP5-immunoreactivity was prominent during the follicular phase, when it strongly decorated the apical plasmalemma of all epithelial cells at ampullary level. During luteal phase, immunoreactivity was discontinuous, being weak to strong at the apex of the secretory cells protruding into the lumen. In the isthmus region, the strongest AQP5-immunoreactivity was seen during follicular phase, with a clear localization in the apical plasmalemma of all the epithelial cells and also on the lateral plasmalemma. AQP2, 3 and 9 were undetectable all along the goat uterine tube. Likely, a collaboration of different AQP molecules sustains the fluid production in the goat uterine tube. AQP1-mediated transudation from the blood capillaries, together with permeation of the epithelium by AQP4 in the basal rim of the epithelial cells and final intervening of apical AQP5, could be involved in fluid production as well as in secretory processes.

Modifications of carbohydrate residues in the sheep oviductal ampulla after superovulation

Epithelium of oviductal ampulla was studied in normal and in superovulated sheep using morphologic analysis and lectin glycohistochemistry. The lining epithelium consisted of two types of cells, ciliated and nonciliated cells. Unlike superovulated samples, the nonciliated cells from control ewes showed apical protrusions indicating an apocrine secretory activity. The ciliated cells showed lectin-binding sites mainly at the level of the cilia which bound all the used lectins except Peanut agglutinin, suggesting the lack of glycans terminating with Galβ1,3GalNAc. In superovulated specimens, the ciliated cells with high mannosylated glycans Concanavalin A (Con A) and GlcNAc and GalNac termini Griffonia simplicifolia agglutinin II (GSA II) and Dolicurus biflorus agglutinin (DBA) decreased. The luminal surface of nonciliated cells showed all investigated sugar residues in controls, whereas it was lacking in high mannosylated (Con A) and terminal GalNAcα1,3(LFucα1,2)Galβ1,3/4GlcNAcβ1 sequence (DBA) in superovulated ewes. Apical protrusions from control ampullae nonciliated cells showed glycans containing mannose, GlcNac, GalNAc, galactose, and α2,3-linked sialic acid (Con A, KOH-sialidase- Wheat germ agglutnin [WGA], GSA II, SBA, Griffonia simplicifolia agglutinin-isolectin B4 [GSA I-B4], Maackia amurensis agglutinin II [MAL II]). The supranuclear cytoplasm of nonciliated cells expressed terminal GlcNAc (GSA II) in all specimens, also O-linked glycans (mucin-type glycans) with GalNAc and sialic acid termini (Helix pomatia agglutinin [HPA] and MAL II) in control animals, and also N-linked glycans with fucose, galactose, lactosamine, and α2,3-linked sialic acid termini (Ulex europaeus agglutinin I [UEA I], GSA I-B4, Ricinus communis agglutinin120 [RCA120], and Sambucus nigra agglutinin [SNA] ) in superovulated ewes. These results report for the first time that the superovulation treatment affects the secretory activity and the glycan pattern of the epithelium lining the sheep oviductal ampulla.

Reciprocity in the developmental regulation of aquaporins 1, 3 and 5 during pregnancy and lactation in the rat

Milk secretion involves significant flux of water, driven largely by synthesis of lactose within the Golgi apparatus. It has not been determined whether this flux is simply a passive consequence of the osmotic potential between cytosol and Golgi, or whether it involves regulated flow. Aquaporins (AQPs) are membrane water channels that regulate water flux. AQP1, AQP3 and AQP5 have previously been detected in mammary tissue, but evidence of developmental regulation (altered expression according to the developmental and physiological state of the mammary gland) is lacking and their cellular/subcellular location is not well understood. In this paper we present evidence of developmental regulation of all three of these AQPs. Further, there was evidence of reciprocity since expression of the rather abundant AQP3 and less abundant AQP1 increased significantly from pregnancy into lactation, whereas expression of the least abundant AQP5 decreased. It would be tempting to suggest that AQP3 and AQP1 are involved in the secretion of water into milk. Paradoxically, however, it was AQP5 that demonstrated most evidence of expression located at the apical (secretory) membrane. The possibility is discussed that AQP5 is synthesized during pregnancy as a stable protein that functions to regulate water secretion during lactation. AQP3 was identified primarily at the basal and lateral membranes of the secretory cells, suggesting a possible involvement in regulated uptake of water and glycerol. AQP1 was identified primarily at the capillary and secretory cell cytoplasmic level and may again be more concerned with uptake and hence milk synthesis, rather than secretion. The fact that expression was developmentally regulated supports, but does not prove, a regulatory involvement of AQPs in water flux through the milk secretory cell.

Immunolocalization of aquaporin 5 during rat ovarian follicle development and expansion of the preovulatory cumulus oophorus

Immunofluorescent localization of aquaporin 5 (AQP5) was investigated in rat ovarian follicles during development and preovulatory cumulus oophorus expansion. Ampullary cumuli oophori complexes (COCs) were examined. Analysis revealed that AQP5 immunostaining appeared in preantral follicles and formed a characteristic ring encircling and touching the oolemma. The staining represented most likely AQP5 functioning at the ends of corona radiata cell projections, anchoring on the oocyte surface. However, several hours after the presumptive preovulatory LH surge, when the process of expansion of COCs started, the AQP5 staining appeared also on the cumulus granulosa cells and in the extracellular matrix. In the postovulatory ampullary COCs the fluorescent ring was not observed, which may be the result of the well-established preovulatory withdrawal of projections from the zona pellucida. At that time-point immunofluorescent staining of AQP5 appeared in most oocytes and was also present in the apical membrane of epithelial cells of the oviduct ampulla. The latter observation suggests that after ovulation AQP5 is involved in the transcellular movement of water in the oviduct ampulla and oocytes in rats.

Reduced hepatic aquaporin-9 and glycerol permeability are related to insulin resistance in non-alcoholic fatty liver disease

BACKGROUND/OBJECTIVES

Glycerol represents an important metabolite for the control of lipid accumulation and hepatic gluconeogenesis. We investigated whether hepatic expression and functionality of aquaporin-9 (AQP9), a channel mediating glycerol influx into hepatocytes, is impaired in non-alcoholic fatty liver disease (NAFLD) and steatohepatitis (NASH) in the context of insulin resistance.

SUBJECTS/METHODS

Liver biopsies were obtained from 66 morbid obese patients undergoing bariatric surgery (66% women, mean body mass index (BMI) 46.1±1.0 kg m(-2)) with available liver echography and pathology analysis of the biopsies in this cross-sectional study. Subjects were classified according to normoglycemia (NG), impaired glucose tolerance (IGT) or type 2 diabetes (T2D). Hepatic expression of AQP9 was analyzed by real-time PCR, western blotting and immunohistochemistry, while glycerol permeability (P(gly)) was measured by stopped-flow light scattering.

RESULTS

AQP9 was the most abundantly (P<0.0001) expressed aquaglyceroporin in human liver (AQP9>>>AQP3>AQP7>AQP10). Obese patients with T2D showed increased plasma glycerol as well as lower P(gly) and hepatic AQP9 expression. The prevalence of NAFLD and NASH in T2D patients was 100 and 65%, respectively. Interestingly, AQP9 expression was decreased in patients with NAFLD and NASH as compared with those without hepatosteatosis, in direct relation to the degree of steatosis and lobular inflammation, being further reduced in insulin-resistant individuals. The association of AQP9 with insulin sensitivity was independent of BMI and age. Consistent with these data, fasting insulin and C-reactive protein contributed independently to 33.1% of the hepatic AQP9 mRNA expression variance after controlling for the effects of age and BMI.

CONCLUSIONS

AQP9 downregulation together with the subsequent reduction in hepatic glycerol permeability in insulin-resistant states emerges as a compensatory mechanism whereby the liver counteracts further triacylglycerol accumulation within its parenchyma as well as reduces hepatic gluconeogenesis in patients with NAFLD.

Agent-based dynamic knowledge representation of Pseudomonas aeruginosa virulence activation in the stressed gut: Towards characterizing host-pathogen interactions in gut-derived sepsis

Background

There is a growing realization that alterations in host-pathogen interactions (HPI) can generate disease phenotypes without pathogen invasion. The gut represents a prime region where such HPI can arise and manifest. Under normal conditions intestinal microbial communities maintain a stable, mutually beneficial ecosystem. However, host stress can lead to changes in environmental conditions that shift the nature of the host-microbe dialogue, resulting in escalation of virulence expression, immune activation and ultimately systemic disease. Effective modulation of these dynamics requires the ability to characterize the complexity of the HPI, and dynamic computational modeling can aid in this task. Agent-based modeling is a computational method that is suited to representing spatially diverse, dynamical systems. We propose that dynamic knowledge representation of gut HPI with agent-based modeling will aid in the investigation of the pathogenesis of gut-derived sepsis.

Methodology/Principal Findings

An agent-based model (ABM) of virulence regulation in Pseudomonas aeruginosa was developed by translating bacterial and host cell sense-and-response mechanisms into behavioral rules for computational agents and integrated into a virtual environment representing the host-microbe interface in the gut. The resulting gut milieu ABM (GMABM) was used to: 1) investigate a potential clinically relevant laboratory experimental condition not yet developed - i.e. non-lethal transient segmental intestinal ischemia, 2) examine the sufficiency of existing hypotheses to explain experimental data - i.e. lethality in a model of major surgical insult and stress, and 3) produce behavior to potentially guide future experimental design - i.e. suggested sample points for a potential laboratory model of non-lethal transient intestinal ischemia. Furthermore, hypotheses were generated to explain certain discrepancies between the behaviors of the GMABM and biological experiments, and new investigatory avenues proposed to test those hypotheses.

Conclusions/Significance

Agent-based modeling can account for the spatio-temporal dynamics of an HPI, and, even when carried out with a relatively high degree of abstraction, can be useful in the investigation of system-level consequences of putative mechanisms operating at the individual agent level. We suggest that an integrated and iterative heuristic relationship between computational modeling and more traditional laboratory and clinical investigations, with a focus on identifying useful and sufficient degrees of abstraction, will enhance the efficiency and translational productivity of biomedical research.

Pregnant phenotype in aquaporin 8-deficient mice

AIM

Aquaporin 8 (AQP8) is expressed within the female reproductive system but its physiological function reminds to be elucidated. This study investigates the role of AQP8 during pregnancy using AQP8-knockout (AQP8-KO) mice.

METHODS

Homozygous AQP8-KO mice were mated, and the conception rate was recorded. AQP8-KO pregnant mice or their offspring were divided into 5 subgroups according to fetal gestational day (7, 13, 16, 18 GD) and newborn. Wild type C57 pregnant mice served as the control group. The number of pregnant mice, total embryos and atrophic embryos, as well as fetal weight, placental weight and placental area were recorded for each subgroup. The amount of amniotic fluid in each sac at 13, 16, and 18 GD was calculated. Statistical significance was determined by analysis of variance of factorial design and chi-square tests.

RESULTS

Conception rates did not differ significantly between AQP8-KO and wild type mice. AQP8-KO pregnant mice had a significantly higher number of embryos compared to wild type controls. Fetal/neonatal weight was also significantly greater in the AQP8-KO group compared to age-matched wild type controls. The amount of amniotic fluid was greater in AQP8-KO pregnant mice than wild type controls, although the FM/AFA (fetal weight/amniotic fluid amount) did not differ. While AQP8-KO placental weight was significantly larger than wild type controls, there was no evidence of placental pathology in either group.

CONCLUSION

The results suggest that AQP8 deficiency plays an important role in pregnancy outcome.

Maternal-fetal fluid balance and aquaporins: from molecule to physiology

Maternal-fetal fluid balance is critical during pregnancy, and amniotic fluid is essential for fetal growth and development. The placenta plays a key role in a successful pregnancy as the interface between the mother and her fetus. Aquaporins (AQPs) form specific water channels that allow the rapid transcellular movement of water in response to osmotic/hydrostatic pressure gradients. AQPs expression in the placenta and fetal membranes may play important roles in the maternal-fetal fluid balance.

Fluctuation of aquaporin 1, 5, and 9 expression in the pig oviduct during the estrous cycle and early pregnancy

Thirteen mammalian aquaporin (AQPs) isoforms with a unique tissue-specific pattern of expression have been identified. To date, 11 isoforms of AQP have been reported to be expressed in female and male reproductive systems. The purpose of our study was to determine the localization and quantitative changes in the expression of AQP1, 5 and 9 within the pig oviduct during different stages of the estrous cycle and early pregnancy. The results demonstrated that AQP1, 5, and 9 were clearly detected in all studied stages of the estrous cycle and pregnancy. AQP1 was localized within oviductal blood vessels. In cyclic gilts, the expression of AQP1 protein did not change significantly between days 10-12 and 14-16 but increased on days 2-4 and 18-20. AQP5 was localized in smooth muscle cells and oviductal epithelial cells. The expression of AQP5 protein did not change significantly between days 10-12 and 14-16 of the estrous cycle but increased on days 2-4 and 18-20. The anti-AQP9 antibody labeled epithelial cells of the oviduct. The expression of AQP9 did not change significantly between days 10-12 and 14-16 of the estrous cycle but increased on days 2-4 and 18-20. In pregnant gilts, expression of AQP1, 5, and 9 did not change significantly in comparison with the estrous cycle. Therefore, a functional and distinctive collaboration seems to exist among diverse AQPs in water handling during the different oviductal phases in the estrous cycle and early pregnancy.

Insulin- and leptin-mediated control of aquaglyceroporins in human adipocytes and hepatocytes is mediated via the PI3K/Akt/mTOR signaling cascade

OBJECTIVE

Glycerol constitutes an important metabolite for the control of lipid accumulation and glucose homeostasis. The impact of obesity and obesity-associated type 2 diabetes as well as the potential regulatory role of insulin and leptin on aquaglyceroporins (AQP) 3, 7, and 9 were analyzed.

RESEARCH DESIGN AND METHODS

The tissue distribution and expression of AQP in biopsies of omental and sc adipose tissue as well as liver were analyzed in lean and obese Caucasian volunteers (n = 63). The effect of insulin (1, 10, and 100 nmol/liter) and leptin (0.1, 1, and 10 nmol/liter) on the expression of the glycerol channels was determined in vitro in human omental adipocytes and HepG2 hepatocytes. The translocation of AQP in response to insulin and isoproterenol was analyzed by immunocytochemistry.

RESULTS

In addition to the well-known expression of AQP7 in adipose tissue, AQP3 and AQP9 were also expressed in both omental and sc adipose tissue. Obese type 2 diabetes patients showed higher expression of AQP in visceral adipose tissue and lower expression of AQP7 in sc adipose tissue and hepatic AQP9. The staining of AQP9 in the plasma membrane of adipocytes was reinforced by insulin, whereas isoproterenol induced the translocation of AQP3 and AQP7 from the lipid droplets to the plasma membrane. Insulin up-regulated all AQP, whereas leptin up-regulated AQP3 and down-regulated AQP7 and AQP9 in adipocytes and hepatocytes. These effects were abrogated by both the phosphatidylinositol 3-kinase inhibitor wortmannin and the mammalian target of rapamycin inhibitor rapamycin.

CONCLUSIONS

Our findings show, for the first time, that insulin and leptin regulate the AQP through the phosphatidylinositol 3-kinase/Akt/mammalian target of rapamycin pathway in human visceral adipocytes and hepatocytes. AQP3 and AQP7 may facilitate glycerol efflux from adipose tissue while reducing the glycerol influx into hepatocytes via AQP9 to prevent the excessive lipid accumulation and the subsequent aggravation of hyperglycemia in human obesity.

Increased female fertility in aquaporin 8-deficient mice

Aquaporin-8 (AQP8) is a water channel expressed extensively in male and female reproductive systems. But its physiological functions are largely unknown. In the present study, we first found significantly increased number of offspring delivered by AQP8(-/-) mothers compared with wild-type mothers in cross-mating experiments. Comparison of ovulation in the two genotypes demonstrated that AQP8(-/-) ovaries released more oocytes (9.5 ± 1.9 vs. 7.1 ± 2.1 in normal ovulation and 37.8 ± 6.7 vs. 27.9 ± 5.7 in superovulation). Histological analysis showed increased number of corpus luteums in mature AQP8(-/-) ovaries, suggesting increased maturation and ovulation of follicles. By RT-PCR, western blot and immunohistochemistry analyses, we determined the expression of AQP8 in mouse ovarian granulosa cells. Granulosa cells isolated from AQP8(-/-) mice showed 45% of decreased membrane water permeability than wild-type mice. As the atresia of ovarian follicles is primarily due to apoptosis of granulosa cells, we analyzed the apoptosis of isolated granulosa cells from wild-type and AQP8(-/-) mice. The results indicated significantly lower apoptosis rate in AQP8(-/-) granulosa cells (21.3 ± 3.6% vs. 32.6 ± 4.3% in AQP8(+/+) granulosa cells). Taken together, we conclude that AQP8 deficiency increases the number of mature follicles by reducing the apoptosis of granulosa cells, thus increasing the fertility of female mice. This discovery may offer new insight of improving female fertility by reducing granulosa cell apoptosis through AQP8 inhibition.

Morphometric and ultrastructural features of the mare oviduct epithelium during oestrus

Morphometric, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) investigations have displayed regional differences in the mare oviductal epithelium. The entire mucosa of the oviduct was lined with a pseudostratified epithelium, which consisted of two distinct cell types, ciliated and non-ciliated. Ciliated cells were predominant in the three different segments of the oviduct and their percentage increased from fimbriae to ampulla and significantly decreased in the isthmus. SEM revealed in the infundibulum finger-like mucosal folds, some of them interconnected, in the ampulla numerous and elaborated branched folds of the mucosa, whereas the isthmus displayed a narrow lumen, short and non-branched mucosal folds. In the ampulla and isthmus the majority of non-ciliated cells showed apical blebs provided or not of short microvilli. TEM displayed different ultrastructural features of ciliated and non-ciliated cells along the oviduct. Isthmus ciliated cells presented a more electron-dense cytoplasm than in infundibulum and ampulla cells and its cilia were enclosed in an amorphous matrix. The non-ciliated cells of infundibulum did not contain secretory granules but some apical endocytic vesicles and microvilli coated by a well developed glycocalyx. Non-ciliated cells of ampulla and isthmus contained secretory granules. Apical protrusions of ampulla displayed two types of secretory granules as well as occasional electron-lucent vesicles. Isthmus non-ciliated cells showed either electron-lucent or electron-dense cytoplasm and not all contained apical protrusions. The electron-dense non-ciliated cells displayed microvilli coated with a well developed glycocalyx. Three types of granules were observed in the isthmus non-ciliated cells. The regional differences observed along the epithelium lining the mare oviduct suggest that the epithelium of the each segment is involved in the production of a distinctive microenvironment with a unique biochemical milieu related to its functional role.

Distribution and quantitative changes in amounts of aquaporin 1, 5 and 9 in the pig uterus during the estrous cycle and early pregnancy

BACKGROUND

Aquaporins (AQPs) are a family of membrane channel proteins that facilitate bulk water transport. To date, 11 isoforms of AQPs have been reported to be expressed in the female and male reproductive systems. The purpose of our study was to determine the localization and quantitative changes in the expression of AQP1, 5 and 9 within the pig uterus during different stages of the estrous cycle and early pregnancy.

METHODS

Immunoperoxidase and semi-quantitative immunoblotting techniques were used to examine the distribution and changes in amounts of AQP1, AQP5 and AQP9 in uteral cells of pigs at the early (Days 2-4), middle (10-12), late (14-16) stage of the luteal phase and late (18-20) stage of the follicular phase of the estrous cycle as well as on Days 14-16 and 30-32 of gestation (the onset and the end of implantation process).

RESULTS

The results demonstrated that AQP1, 5, and 9 were clearly detected in all studied stages of the estrous cycle and pregnancy. AQP1 was localized within uterine blood vessels. In cyclic gilts, endometrial and myometrial expression of AQP1 protein did not change significantly but increased during gestation. AQP5 was localized in smooth muscle cells and uterine epithelial cells. Endometrial expression of AQP5 protein did not change significantly between Days 2-4 and 10-12 of the estrous cycle but increased on Days 14-16 and 18-20 as well as during early pregnancy. Myometrial expression of AQP5 did not differ significantly during the estrous cycle but increased in the pregnancy. The anti-AQP9 antibody labeled uterine epithelial cells of uterus. Endometrial expression of AQP9 did not change significantly between Days 2-4 and 10-12 of the estrous cycle but increased on Days 14-16 and 18-20 as well as during early pregnancy.

CONCLUSIONS

The results suggest that a functional and distinctive collaboration exists among diverse AQPs in water handling during the different uterine phases in the estrous cycle and early pregnancy.

Beyond the mouse model: using Drosophila as a model for sperm interaction with the female reproductive tract

Although the fruit fly, Drosophila melanogaster, has emerged as a model system for human disease, its potential as a model for mammalian reproductive biology has not been fully exploited. Here we describe how Drosophila can be used to study the interactions between sperm and the female reproductive tract. Like many insects, Drosophila has two types of sperm storage organs, the spermatheca and seminal receptacle, whose ducts arise from the uterine wall. The spermatheca duct ends in a capsule-like structure surrounded by a layer of gland cells. In contrast, the seminal receptacle is a slender, blind-ended tubule. Recent studies suggest that the spermatheca is specialized for long-term storage, as well as sperm maturation, whereas the receptacle functions in short-term sperm storage. Here we discuss recent molecular and morphological analyses that highlight possible themes of gamete interaction with the female reproductive tract and draw comparison of sperm storage organ design in Drosophila and other animals, particularly mammals. Furthermore, we discuss how the study of multiple sperm storage organ types in Drosophila may help us identify factors essential for sperm viability and, moreover, factors that promote long-term sperm survivorship.

Immunohistochemical searching for estrogen and progesterone receptors in women vocal fold epithelia

Larynx is extremely sensitive to endocrinologic changes. Most vocal fold mucosa alterations are caused by changes in vocal fold liquid content and its epithelial changes. Estrogen and progesterone interfere and change this liquid content in the vocal folds. Our goal with the present paper is to study the presence of estrogen and progesterone receptors on vocal fold epithelium in 19 vocal fold epithelium specimens that did not present any indication of disease, especially inflammatory disease. We discarded those cases of patients above 40 years of age and those below 15.

RESULTS

We found progesterone receptors in 18 of the 19 patients. The progesterone receptors are located both in the nucleus and the cytoplasm of cells, and mainly in the basal layer. There was no report of estrogen receptors present in the vocal folds.

CONCLUSION

Vocal fold epithelium bears progesterone receptors, in the cytoplasm and in the nucleus. We did not find estrogen receptors in the epithelia of the vocal folds investigated.

Immunolocalization of aquaporin 1, 5, and 9 in the female pig reproductive system

Thirteen mammalian aquaporin (AQP) isoforms have been identified, and they have a unique tissue-specific pattern of expression. AQPs have been documented in the reproductive system of both male and female humans, rats, and mice. However, tissue expression and cellular and subcellular localization of AQPs are unknown in the female reproductive system of pigs. In this study, AQP1 immunoreactivity was detected in the capillary endothelium of the ovary. Distinct immunolabeling of capillary endothelium was also observed in the oviduct and uterus. AQP5 was expressed in flattened follicle cells of primordial follicles, granulosa cells of developing ovarian follicles, and muscle cells of the oviduct and uterus. Staining of AQP5 was also observed in the epithelial cells of the oviduct and uterine epithelium. AQP9 immunoreactivity was observed in granulosa cells of developing follicles. AQP9 was also localized in the luminal epithelial cells of the oviduct and uterine epithelia cells. This is, to our knowledge, the first study that shows tissue expression and cellular and subcellular localization of AQPs in the reproductive system of the female pig. Moreover, these results suggest that several subtypes of the AQPs (AQP1, 5, and 9) are involved in regulation of water homeostasis in the reproductive system of gilts.

Female reproductive tract fluids: composition, mechanism of formation and potential role in the developmental origins of health and disease

The oviduct and uterus provide the environments for the earliest stages of mammalian embryo development. However, little is known about the mechanisms that underlie the formation of oviduct and uterine fluids, or the extent to which the supply of nutrients via these reproductive tract tissues matches the nutrient requirements of early embryos. After reviewing our limited knowledge of these phenomena, a new experimental paradigm is proposed in which the epithelia lining the endosalpinx and endometrium are seen as the final components in a supply line that links maternal diet at one end and embryo uptake of nutrients at the other. When considered in this way, the oviduct and uterine epithelia become, for a few days, potentially the most critical maternal tissues in the establishment of a healthy pregnancy. In fulfilling this ‘gatekeeper’ role, female reproductive tract fluids have a key role in the ‘developmental origins of health and disease’ concept.

Expression of aquaporin 9 in rat liver and efferent ducts of the male reproductive system after neonatal diethylstilbestrol exposure

Aquaporins (AQP) have important solute transport functions in many tissues including the epididymal efferent ducts (ED) and in the liver. We investigated the effect of neonatal exposure to diethylstilbestrol (DES) on AQP9 expressions in the ED and in the liver of rats. DES was administered from day 2 to day 20 postnatally at a dose of 4,8 microg/day, and AQP9 protein and mRNA were measured by immunoblotting and real-time PCR, respectively, along with immunohistochemistry. DES caused hepatic downregulation of AQP9 at both the protein and mRNA level; however, decreased AQP9 labeling was only observed in the periportal zone. In the ED, AQP9 protein expression was increased in the DES-treated animals by 300% that could be ascribed to a widening of the ED lumen, whereas no difference was observed in AQP9 mRNA expression. Immunohistochemical findings revealed that AQP9 expression was confined to the epithelial cells of the ED. In conclusion, neonatal DES exposure appears to upregulate AQP9 channels in the ED in male rats, whereas a downregulation in the hepatic expression was observed, particularly in the periacinous area.

Catechol-O-Methyltransferase and Methoxyestradiols Participate in the Intraoviductal Nongenomic Pathway Through Which Estradiol Accelerates Egg Transport in Cycling Rats1

Estradiol (E(2)) accelerates oviductal egg transport through intraoviductal nongenomic pathways in cyclic rats and through genomic pathways in pregnant rats. This shift in pathways, which we have provisionally designated as intracellular path shifting (IPS), is caused by mating-associated signals and represents a novel and hitherto unrecognized phenomenon. The mechanism underlying IPS is currently under investigation. Using microarray analysis, we identified several genes the expression levels of which changed in the rat oviduct within 6 hours of mating. Among these genes, the mRNA level for the enzyme catechol-O-methyltransferase (COMT), which produces methoxyestradiols from hydroxyestradiols, decreased 6-fold, as confirmed by real-time PCR. O-methylation of 2-hydroxyestradiol was up to 4-fold higher in oviductal protein extracts from cyclic rats than from pregnant rats and was blocked by OR486, which is a selective inhibitor of COMT. The levels in the rat oviduct of mRNA and protein for cytochrome P450 isoforms 1A1 and 1B1, which form hydroxyestradiols, were detected by RT-PCR and Western blotting. We explored whether methoxyestradiols participate in the pathways involved in E(2)-accelerated egg transport. Intrabursal application of OR486 prevented E(2) from accelerating egg transport in cyclic rats but not in pregnant rats, whereas 2-methoxyestradiol (2ME) and 4-methoxyestradiol mimicked the effect of E(2) on egg transport in cyclic rats but not in pregnant rats. The effect of 2ME on egg transport was blocked by intrabursal administration of the protein kinase inhibitor H-89 or the antiestrogen ICI 182780, but not by actinomycin D or OR486. We conclude that in the absence of mating, COMT-mediated formation of methoxyestradiols in the oviduct is essential for the nongenomic pathway through which E(2) accelerates egg transport in the rat oviduct. Yet unidentified mating-associated signals, which act directly on oviductal cells, shut down the E(2) nongenomic signaling pathway upstream and downstream of methoxyestradiols. These findings highlight a physiological role for methoxyestradiols in the female genital tract, thereby confirming the occurrence of and providing a partial explanation for the mechanism underlying IPS.

A case of hydrosalpinx associated with the menstrual cycle

OBJECTIVE

To describe a case report of hydrosalpinx that changed dramatically in size during the menstrual cycle.

DESIGN

Case report.

SETTING

University teaching hospital reproductive endocrinology and infertility practice.

PATIENT(S)

A 32-year-old woman with a history of medical and surgical treatments of endometriosis who sought infertility treatment.

INTERVENTION(S)

Transvaginal ultrasonography performed sequentially during menstrual cycles.

MAIN OUTCOME MEASURE(S)

Size of hydrosalpinx-like image.

RESULT(S)

The size of the hydrosalpinx-like image in the left adnexal region varied; it peaked during the ovulatory period and then remarkably diminished in a cyclic manner. Laparoscopy revealed a dense adhesion between the left tubal fimbriated end and the posterior uterine wall, which led to terminal obstruction of the tube.

CONCLUSION(S)

Change in the volume of the hydrosalpinx in this case was speculated to reflect the normal tubal fluid production regulated by ovarian hormones.

Human 2D (index) and 4D (ring) digit lengths: their variation and relationships during the menstrual cycle

It is known that there are sexually dimorphic differences in relative and absolute lengths of the index (2nd) and ring (4th) fingers and that the sizes of laterally-paired soft tissues (e.g. ears and fingers) show changes across the menstrual cycle. The aim of the present study was to determine whether cyclical changes in the digit lengths of the index and ring fingers also occur and, if so, to what extent these are related to changing patterns of circulating sex steroids. Digit lengths were assessed over two cycles in groups of right-handed females (19-21 years of age) who were divided on the basis of whether or not they were taking oral contraceptive pills (n = 13 and n = 6 respectively). Using callipers, finger lengths were measured on photocopy images of both hands taken at 4-day intervals for a total of 56 days. We tested the following null hypotheses: (1) digit length measurements do not exhibit fluctuations across the menstrual cycle; (2) there is no evidence of lateral asymmetry between measurements made on both hands; (3) the lengths of digits 2 and 4 do not differ in either hand. Null hypotheses were tested using Page's L trends test for related samples (cyclical fluctuations) and paired Student's t tests (left-right asymmetries and within-hand digital differences). In those not taking oral contraceptives, finger lengths and 2D:4D digit ratios fluctuated across the cycle with values tending to increase in the pre-ovulatory period and decline thereafter. Left-right asymmetries varied in a similar fashion with lengths generally being larger, and lateral asymmetries smaller, in the dominant hand. Although sample sizes were smaller, some of these patterns were retained but others were perturbed in those practising oral contraception. We conclude that finger lengths are cycle-dependent and that account should be taken of this, and of oral contraceptive usage, in future studies on female digit lengths and their ratios.

Effect of oestradiol and progesterone on the instant and directional velocity of microsphere movements in the rat oviduct: gap junctions mediate the kinetic effect of oestradiol

The oviducal transport of eggs to the uterus normally takes 72–96 h in the rat, but this is reduced to less than 20 h after a single injection of oestradiol (E2). This accelerated transport is associated with an increased frequency of pendular movements in the isthmic segment of the oviduct, with increased levels of the gap junction (GJ) component Connexin (Cx) 43, and is antagonised by progesterone (P). In the present study, we investigated the effect of these hormones on the instant and directional velocity of pendular movements and the role of the GJ and its Cx43 component in the kinetic response of the oviduct to E2 and P. Using microspheres as egg surrogates, microsphere instant velocity (MIV) was measured following treatment with E2, P or P + E2, which accelerate or delay egg transport. Microspheres were delivered into the oviduct of rats on Day 1 of pregnancy and their movement within the isthmic segment was recorded. Oestrogen increased MIV with faster movement towards the uterus. After P or P + E2, MIV was similar to that in the control group. Two GJ uncouplers, namely 18α- and 18β-glycyrrhetinic acid, blocked the effect of E2 on MIV. Connexin 43 mRNA levels increased over that seen in control with all treatments. In conclusion, the effects of E2 on MIV resulted in faster movements that produced accelerated egg transport towards the uterus. Gap junctions are probably involved as smooth muscle synchronisers in this kinetic effect of E2, but the opposing effects of E2 and P are not exerted at the level of Cx43 transcription.

Effects of 3-beta-diol, an androgen metabolite with intrinsic estrogen-like effects, in modulating the aquaporin-9 expression in the rat efferent ductules

BACKGROUND

Fluid homeostasis is critical for normal function of the male reproductive tract and aquaporins (AQP) play an important role in maintenance of this water and ion balance. Several AQPs have been identified in the male, but their regulation is not fully comprehended. Hormonal regulation of AQPs appears to be dependent on the steroid in the reproductive tract region. AQP9 displays unique hormonal regulation in the efferent ductules and epididymis, as it is regulated by both estrogen and dihydrotestosterone (DHT) in the efferent ductules, but only by DHT in the initial segment epididymis. Recent data have shown that a metabolite of DHT, 5-alpha-androstane-3-beta-17-beta-diol (3-beta-diol), once considered inactive, is also present in high concentrations in the male and indeed has biological activity. 3-beta-diol does not bind to the androgen receptor, but rather to estrogen receptors ER-alpha and ER-beta, with higher affinity for ER-beta. The existence of this estrogenic DHT metabolite has raised the possibility that estradiol may not be the only estrogen to play a major role in the male reproductive system. Considering that both ER-alpha and ER-beta are highly expressed in efferent ductules, we hypothesized that the DHT regulation of AQP9 could be due to the 3-beta-diol metabolite.

METHODS

To test this hypothesis, adult male rats were submitted to surgical castration followed by estradiol, DHT or 3-beta-diol replacement. Changes in AQP9 expression in the efferent ductules were investigated by using immunohistochemistry and Western blotting assay.

RESULTS

Data show that, after castration, AQP9 expression was significantly reduced in the efferent ductules. 3-beta-diol injections restored AQP9 expression, similar to DHT and estradiol. The results were confirmed by Western blotting assay.

CONCLUSION

This is the first evidence that 3-beta-diol has biological activity in the male reproductive tract and that this androgen metabolite has estrogen-like activity in the efferent ductules, whose major function is the reabsorption of luminal fluid.