Quercetin alters uterine fluid volume and aquaporin (AQP) subunits (AQP-1, 2, 5 & 7) expression in the uterus in the presence of sex-steroids in rats

Taurine is essential for mouse uterine luminal fluid resorption during implantation window via the SCNN1A and AQP8 signaling†

Uterine fluid homeostasis during peri-implantation is crucial for successful embryo implantation. Taurine (Tau) plays a crucial role in regulating osmotic pressure and ion transport. However, the precise mechanisms underlying Tau-mediated regulation of uterine fluid homeostasis during peri-implantation in mice remain unclear. In this study, we generated a Tau-deficient mouse model by administering Tau-free diet to Csad knockout (Csad-/-) mice to block endogenous Tau synthesis and exogenous Tau absorption (Csad-/--Tau free). Our findings demonstrated that Csad-/--Tau free mice with diminished level of Tau exhibited decreased rates of embryo implantation and impaired fertility. Further analysis revealed that the expression of Scnn1a was down-regulated during the implantation window, while Aqp8 was upregulated in Csad-/--Tau free mice, leading to uterine luminal fluid retention and defects in luminal closure, resulting in failed embryo implantation. Additionally, it was also found that E2 inhibited uterine Csad expression and Tau synthesis, while P4 promoted them. Therefore, our findings suggest that ovarian steroid hormones regulate Csad expression and Tau synthesis, thereby affecting release and resorption of uterine luminal fluid, ultimately impacting embryo implantation success.

Pyometra alters uterine aquaporins related with lipopolysaccharide concentrations and antioxidant enzyme activities in bitches

Pyometra is a common life-threatening inflammatory disease with a complex etiopathogenesis that develops during the diestrus stage and can be observed in elderly intact bitches. The present study evaluated five aquaporin (AQP1, AQP2, AQP3, AQP5, and AQP9) transcript abundances and immunolocalization in the uterine tissue, and investigated their relationship with uterine tissue and blood lipopolysaccharide (LPS) concentration, superoxide dismutase (SOD) and glutathione peroxidase (GPX) activity, and nitric oxide (NO) production in dogs suffering from pyometra. The study sampled 36 client-owned intact bitches from different breeds, of which 24 cases were diagnosed with pyometra. Twelve of these bitches in the diestrus stage that presented for elective ovariohysterectomy were used as the control group. Blood samples were collected into tubes without anticoagulant for serum progesterone, LPS concentration, and antioxidant activities at the time of diagnosis. Bacteriological and tissue samples from the uteri were collected after the ovariohysterectomy. The tissue samples were used to determine antioxidant activity, and hormone and toxin concentrations. Transcript abundance of uterine AQPs were determined by qPCR, and their presence and localization were determined by by immunohistochemistry. For all pyometra samples, the bacteria isolated from the uterine swabs were Escherichia coli. Compared to the control group, AQP1, AQP2, and AQP5 were downregulated more than 2-fold, whereas AQP9 was upregulated nearly 3-fold and AQP3 was upregulated more than 4-fold in the pyometra affected uteri (P<0.05). Uterine AQP1 was moderately negatively correlated with serum LPS concentration (r=-0.568, P<0.01) and tissue NO production (r=-0.407, P<0.05). AQP5 was positively correlated with serum SOD activity (r=0.485, P<0.05) and negatively correlated with serum LPS concentration (r=-0.512, P<0.05). AQP9 was negatively correlated with tissue SOD and serum GPx activity. This is the first study to identify AQP9 transcript abundance and immunolocalization in canine uterine tissue. Uterine AQP1, AQP2, AQP3, AQP5, and AQP9 transcript abundances were altered in spontaneously developed canine pyometra while AQP transcript abundance was negatively related to serum toxin concentration, NO production, and antioxidant enzyme activity. Further studies should be conducted to determine the role of altered abundances of AQPs transcripts in pyometra pathogenesis.

Cervical fluid pH, electrolytes and osmolarity changes and expression of ion transporters (ENaC, CFTR and AQP) in cervix of women with primary unexplained infertility

BACKGROUND

Unexplained infertility could arise from a defect in the cervix. However, the contribution of abnormal cervical fluid microenvironment to this problem still needs to be identified. Therefore, this study identifies the changes in the cervical fluid microenvironment, i.e., pH, electrolytes and osmolarity as well as expression of ion transporters in the cervix including ENaC, CFTR and AQP in fertile women and in women suffering from primary unexplained infertility.

METHODS

Fertile women and women with unexplained infertility but having regular 28-day menstrual cycles were chosen in this study, Day-22 serum progesterone levels were determined. In the meantime, serum FSH and LH levels were determined on day 2 while, cervical flushing was performed at day 14 to analyse changes in the cervical fluid pH, osmolarity, Na+ and Cl- levels. Meanwhile, cells retrieved from cervical fluid were subjected to mRNA expression and protein distribution analysis for CFTR, AQP and ENaC by qPCR and immunofluorescence, respectively.

RESULTS

No significant changes in serum progesterone, FSH and LH levels were observed between the two groups. However, cervical fluid pH, osmolarity, Na+ and Cl- levels were significantly lower in primary unexplained infertile group when compared to fertile group. Expression of CFTR and AQP (AQP 1, AQP 2, AQP 5 and AQP 7) in endocervical cells was lower and expression of β-ENaC was higher in primary unexplained infertile women (p < 0.05 when compared to fertile group).

CONCLUSIONS

Alterations in the cervical fluid microenvironment linked to the defective ion transporter expression in the cervix might contribute towards the unfavourable condition that accounts for unexplained infertility in women.

Changes in fluid composition and expression of ion channels in rat cervix during different phases of the estrus cycle

We investigated changes in the composition of cervical fluid at different phases of the female rat reproductive cycle. Fluid was collected from the cervix of rats by direct cervical flushing and analyzed for changes in Na⁺ and Cl^- content and osmolarity. Following sacrifice, the cervix was harvested and expressions of mRNA and protein for ENaCs, CFTR and AQPs were measured using qPCR and immunohistochemistry, respectively. Cervical fluid Na⁺ and Cl^- content was high during estrus, but osmolarity was high during metestrus and diestrus. Expressions of CFTR, AQP-1 and AQP-2 in the cervix were high during estrus, but low during diestrus. Expression of ENaC (α, β, γ), AQP-5 and AQP-7 was high during metestrus and diestrus and low during estrus. Changes in expression of ion channels in the cervix could explain changes in cervical fluid composition during the estrus cycle phases that could affect female fertility.

Quercetin Prevents Lipopolysaccharide-Induced Experimental Preterm Labor in Mice and Increases Offspring Survival Rate

Premature labor is still a worldwide problem, causing serious social economic burden and family burden. Currently, there is no effective way to prevent preterm labor. Since inflammation increases the risk of preterm birth and quercetin is reported to have anti-inflammation, immune-enhancement, and antioxidative effects, this study aims to explore whether quercetin exerts inhibitory effect on preterm labor in mice and increases offspring survival. Lipopolysaccharide (LPS) is one of the commonly used drugs in the inflammatory animal model of preterm birth. On day 15 of pregnancy, mice received a dose of vehicle phosphate-buffered saline (PBS) or a dose of quercetin (low concentration, 30 mg/kg; medium concentration, 90 mg/kg; high concentrations, 150 mg/kg) via oral gavage. After 2 h, mice received a dose of LPS (50 μg/kg) or vehicle intraperitoneally (i.p.). In the absence of quercetin, a 100% incidence of preterm labor was observed in LPS-treated mice, and the fetuses were all died. Medium concentration of quercetin significantly prevented 63.5% of LPS-induced inflammatory preterm labor, and the survival rate of pups on day 22 was 83.76%. Specifically, quercetin significantly inhibited LPS-induced upregulation of NF-kappa-B/P65(RELA), AP-1/C-JUN(JUN), cyclooxygenase-2(PTGS2), and interleukin 6(IL6) in mice myometrium on mRNA level and inhibited the upregulation of P65 and C-JUN on protein level. Based on these observations, we concluded that quercetin exerts inhibitory effect on LPS-induced experimental mice preterm labor and increases offspring survival through a mechanism involving NF-κB/AP-1 pathway.

Hormonal control of vas deferens fluid volume and aquaporin expression in rats

Precise regulation of vas deferens fluid volume which is important for sperm survival might be influenced by testosterone. In order to investigate changes in vas deferens fluid volume and aquoporins (AQP) isoforms expression under testosterone influence, orchidectomized Sprague-Dawley rats were given 125 and 250 µg/kg/day testosterone with or without flutamide, an androgen receptor blocker or finasteride, a 5alpha-reductase inhibitor for seven consecutive days. Following treatment completion, vas deferens was perfused and changes in the fluid secretion rate and osmolality were determined in the presence of acetazolamide. Rats were then sacrificed and vas deferens was harvested for histology, tissue expression and distribution analyses of AQP-1, AQP-2, AQP-5, AQP-7 and AQP-9 proteins by Western blotting and immunohistochemistry, respectively. Our findings indicate that testosterone causes vas deferens fluid secretion rate to increase, which was antagonized by acetazolamide. Fluid osmolality increased following testosterone treatment and further increased when acetazolamide was given. Co-administration of flutamide or finasteride with testosterone causing both fluid secretion rate and osmolality to decrease. Histology revealed increased size of vas deferens lumen with increased thickness of vas deferens stroma. Expression of AQP-1, AQP-2 and AQP-9 were detected in vas deferens but not AQP-5 and AQP-7, and the levels of these proteins were increased by testosterone treatment mainly at the apical membrane of vas deferens epithelium. In conclusion, increased in vas deferens fluid secretion rate under testosterone influence mediated via the up-regulation of AQP-1, 2 and 9 might be important for vas deferens fluid homeostasis in order to ensure normal male fertility.

Effects of Marantodes pumilum (Kacip Fatimah) on vaginal pH and expression of vacoular ATPase and carbonic anhydrase in the vagina of sex-steroid deficient female rats

BACKGROUND

In sex-steroid deficiency, increased in the pH of vaginal fluid is due to low estrogen levels.

HYPOTHESIS

Consumption of Marantodes pumilum leaves helps to ameliorate increased in vaginal fluid pH in sex-steroid deficient condition.

PURPOSE

To investigate changes in vaginal fluid pH and expression of proteins that participate in pH changes i.e vacoular (V)-ATPases and carbonic anhydrases (CA) in the vagina following M. pumilum leaves consumption.

METHODS

Ovariectomized adult female rats were treated orally with M. pumilum leaves extract (MPE) at 100, 250 and 500 mg/kg.b.w and estradiol at 0.2 µg/kg/b.w for 28 days. At the end of the treatment, vaginal fluid pH was measured in anesthetised rats by using micropH probe. Following sacrificed, levels of V-ATPase and CA proteins and mRNAs in the vagina were identified by Western blotting and real-time PCR, respectively. Protein distribution was visualized by immunohistochemistry.

RESULTS

Administration of MPE causes the pH of vaginal fluid to decrease and expression and distribution of vaginal V-ATPase A & B and CA II, III, IX, XII and XIII to increase.

CONCLUSIONS

The decrease in vaginal fluid pH following MPE treatment suggested that this herb has potential to be used to ameliorate vaginal fluid pH changes in sex-steroid deficient condition.