Expressions of aquaporin family in human luteinized granulosa cells and their correlations with IVF outcomes.

STUDY QUESTION: Are mRNAs for specific aquaporins (AQPs) expressed in human luteinized granulosa cells (GCs) and are their expression levels correlated with in vitro fertilization (IVF) outcomes?

SUMMARY ANSWER: The mRNAs of AQP1-7, 9, 11, and 12 were expressed in human luteinized GCs; the level of AQP1 mRNA was negatively associated with retrieved oocyte number and the level of AQP7 mRNA was positively associated with fertilization rate.

WHAT IS KNOWN ALREADY: mRNAs of AQP1-4 and AQP9 have been detected in human GCs.

STUDY DESIGN, SIZE, DURATION: Prospective observational study involving 111 women undergoing a stimulated IVF cycle.

PARTICIPANTS/MATERIALS, SETTING, METHODS: In a preliminary experiment on 27 women, the mRNA expression of AQP0-12 in GCs was explored by RT-PCR. In the main experiment, luteinized GCs were obtained from 111 women at the time of oocyte retrieval of whom 102 had an embryo replacement. Real-time quantitative RT-PCR (qRT-PCR) was performed to quantify the mRNA level of AQP1-7, 9, 11, and 12. The mRNA for luteinizing hormone receptor (LHR) and steroidogenic acute regulatory protein (StAR) were also quantified by qRT-PCR.

MAIN RESULTS AND THE ROLE OF CHANCE: mRNAs for AQP0, 8 and 10 were not detected in the preliminary experiment. In samples from 111 women, retrieved oocyte number was negatively associated with the mRNA levels of AQP1, 4, 6, and 11 and LHR (r = -0.311, r = -0.233, r = -0.203, r = -0.194, and r = -0.202, respectively, P < 0.05 for each), however, after adjustment for woman's age and serum anti-Müllerian hormone (AMH) levels, only correlation with AQP1 was found (r = -0.299, P < 0.05). BMI was negatively associated (after adjustment for age) with the mRNA level of AQP7 (r = -0.259, P < 0.05). Fertilization rate was positively associated with the mRNA level of AQP7 (r = 0.269, P < 0.05). The number or quality of embryos or clinical pregnancy was not associated with the mRNA levels of any of ten AQP subtypes. The mRNA levels for the ten AQP subtypes were correlated positively with LHR expression but negatively with StAR expression. Amongst high responders (oocyte number ≥14), the mRNA levels of AQP11 (1.4 ± 0.7 versus 1.7 ± 0.6) and LHR (1.3 ± 0.7 versus 1.7 ± 0.7) were significantly lower in the group with PCOS than in the non-PCOS group.

LIMITATIONS, REASONS FOR CAUTION: A relative small number of subjects in PCOS group is the main limitation of our study. P-values were not corrected for multiple comparisons.

WIDER IMPLICATION OF THE FINDINGS: AQP1 may be one of the factors that modulate individual ovarian response to exogenous gonadotrophin. The mRNA level of AQP7 was positively associated with fertilization rate, which is a surrogate marker of oocyte competence, thus expression of AQP7 could be a marker for adequate folliculogenesis and healthy oocytes.

STUDY FUNDING/COMPETING INTERESTS: This work was supported by grant no. A120043 from the Korea Health Care Technology R&D Project, Ministry of Health and Welfare, Korea. None of the authors has any conflict of interest to declare.