Reduced expression and function of aquaporin-3 in mouse metaphase-II oocytes induced by controlled ovarian hyperstimulation were associated with subsequent low fertilization rate.
ABSTRACT Aquaporin-3 (AQP3), one isoform of water channel family, has been found to be expressed in mouse oocytes. The present study aimed to investigate whether functional AQP3 was expressed in oocytes induced by controlled ovarian hyperstimulation (COH), and whether altered oocyte AQP3 expression was associated with changes in fertilization rate.
Sixty ICR female mice were divided into two groups: COH and control. AQP3 mRNA expression of mouse metaphase II (MII) oocytes was quantified by real-time RT-PCR. The water permeability of oocytes was assessed with cell swelling test. The fertilization profiles of oocytes were generated via in vitro fertilization.
AQP3 mRNA was expressed in both natural and COH-induced mouse oocytes. COH significantly reduced AQP3 mRNA expression. The volume of oocytes was significantly increased after exposure to hypotonic medium and pretreatment with HgCl(2) attenuated hypotonic medium-induced increase in oocyte volume and water permeability coefficient (Pf). Furthermore, the expression of AQP3, Pf and the fertilization rate were significantly lower in COH oocytes than those in control.
AQP3 might play an important role in controlling oocyte quality and a low in vitro fertilization rate of COH mice might, in part, result from reduced AQP3 expression and water permeability in mouse oocytes.
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ABSTRACT: This study aimed to investigate whether aquaporin 3 (Aqp3) mRNAs are expressed in immature oocytes and altered during in vitro maturation process. Five- to 6-week-old female ICR mice were primed by gonadotropin for 24 and 48 h. Immature oocytes obtained 48 h after priming were also matured in vitro for 17 to 18 h. In vivo matured oocytes were obtained after 48 h priming followed by hCG injection. Total RNAs were extracted from 80 to 150 oocytes in each experimental group, and the levels of Aqp3 mRNA were quantified by real-time reverse transcriptase polymerase chain reaction. The experiments were repeated twice using different oocytes. The Aqp3 mRNA was expressed in immature oocytes, as well as in in vitro and in vivo matured oocytes. The expression level was higher in immature oocytes obtained 48 h after priming (17.2 ± 8.6, mean ± SD) than those with no priming (5.7 ± 0.8) or obtained 24 h after priming (2.5 ± 0.8). The expression of Aqp3 mRNA decreased after in vitro maturation (1.2 ± 0.5), which was similar to in vivo matured oocytes (1.0 ± 0.0). Our work demonstrated that Aqp3 mRNA expression increased during the development of immature oocyte but decreased after completion of in vitro maturation. The results indicate that AQP3 is certainly needed for the acquisition of immature oocytes' full growing potential within antral follicles.Zygote 02/2011; 19(1):9-14. · 1.50 Impact Factor
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ABSTRACT: OBJECTIVE: To investigate the effects of cryoprotectants on the expression of AQP7 in oocytes. DESIGN: Experimental animal study. SETTING: University-based research laboratory. ANIMAL(S): Adult female C57BL/6J mice. INTERVENTION(S): In metaphase II (MII) oocytes obtained from adult female C57BL/6J mice and from donations by fertile women, the mouse oocytes were treated with human tubal fluid medium containing 8% ethylene glycol (EG), 9.5% dimethylsulfoxide (DMSO), and 0.5 M sucrose, respectively; 293T cells transfected with GFP-hAQP7 expression vector were treated with the same solutions. MAIN OUTCOME MEASURE(S): AQP7 expression in oocytes examined by reverse-transcriptase-nested polymerase chain reaction and immunofluorescence, changes in the volume of mouse oocytes treated with different solutions calculated to determine their permeability to water, and survival rates of vitrified oocytes. RESULT(S): AQP7 is expressed in human and mouse oocytes. Cryoprotectants, including EG, DMSO, and sucrose, up-regulated AQP7 expression in mouse oocytes and 293T cells transfected with GFP-hAQP7 expression vector. Compared with other cryoprotectants, DMSO stimulated higher expression of AQP7, and this was associated with faster cell volume recovery and lower survival rates of vitrified oocytes. CONCLUSION(S): DMSO up-regulates AQP7 expression in mouse oocytes more than EG. This may facilitate water diffusion and reduce the time for oocytes to reach osmotic balance with the cryoprotectant solution during cryopreservation.Fertility and sterility 01/2013; · 3.97 Impact Factor
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ABSTRACT: 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.Acta histochemica 11/2013; · 1.61 Impact Factor