21-Hydroxylase-derived steroids in follicles of nonobese women undergoing ovarian stimulation for in vitro fertilization (IVF) positively correlate with lipid content of luteinized granulosa cells (LGCs) as a source of cholesterol for steroid synthesis.

CONTEXT: Mineralocorticoid synthesis by the nonhuman primate periovulatory follicle enhances luteinization. Whether a similar event occurs in women undergoing in vitro fertilization (IVF) is unknown. OBJECTIVE: The objective of the study was to determine whether human luteinized granulosa cells (LGCs) produce mineralocorticoids derived from 21-hydroxylase activity and also express mRNA for 21-hydroxylase and the mineralocorticoid receptor. DESIGN: This was a prospective cohort study. SETTING: The study was conducted at an academic center. PATIENTS: LGC lipid content and follicle fluid (FF) hormone analysis was performed on 27 nonobese IVF women. LGCs from six additional nonobese IVF women were used for gene expression studies. INTERVENTION: At oocyte retrieval, FF was aspirated from the first follicle (≥16 mm in size) of each ovary and pooled LGCs were collected. MAIN OUTCOME MEASURES: FF steroid analysis was performed by liquid chromatography-tandem mass spectrometry. LGCs were stained with lipid fluorescent dye BODIPY FL C16 to estimate lipid content by confocal microscopy as a cholesterol source for steroidogenesis in vivo. Quantitative real-time PCR was performed using LGCs to detect 21-hydroxylase and mineralocorticoid receptor mRNA expression. Pearson correlation coefficients determined associations between FF steroid levels and LGC lipid content. RESULTS: FF levels of the 21-hydroxylase-derived steroids, 11-deoxycorticosterone [DOC, 39.97, median (13.94-63.02) ng/mL] and 11-deoxycortisol [11DOC, 2.07 (0.69-5.01) ng/mL], along with the 21-hydroxylase precursor 17-hydroxyprogesterone [1268.21 (493.26-3558.39) ng/mL], positively correlated with LGC lipid content (84 ± 43 fluorescent units/sample) (P ≤ .05, all steroids). 21-Hydroxylase and mineralocorticoid receptor mRNA expression was detected in LGCs. CONCLUSIONS: Human LGCs likely synthesize 21-hydroxylase-derived mineralocorticoids from cholesterol-containing lipid in vivo to promote postovulatory luteinization via mineralocorticoid receptor-mediated events.

A novel approach to quantifying ovarian cell lipid content and lipid accumulation in vitro by confocal microscopy in lean women undergoing ovarian stimulation for in vitro fertilization (IVF).

PURPOSE: To quantify intracellular lipid levels in cumulus cells (CCs) and mural granulosa cells (MGCs) of lean women undergoing gonadotropin therapy for in vitro fertilization (IVF), based upon different cell preparation methods. METHODS: CCs and MGCs from 16 lean women undergoing ovarian stimulation for IVF were studied. Cells were pooled by cell type, with each type of cell separated into two groups for determination of initial lipid content (Method 1) and subsequent lipid accumulation in vitro (Method 2). Cells for initial lipid content were immediately fixed at the time of the oocyte retrieval with 4% paraformaldehyde in suspension, while those for subsequent lipid accumulation in vitro were cultured for 4 h with 5% fetal calf serum and then fixed. Cells were treated with lipid fluorescent dye BODIPY® FL C16 and nuclear marker DAPI. Intracellular lipid was quantified by confocal microscopy, using ImageJ software analysis. RESULTS: There was no significant effect of cell type (P = 0.2) or cell type-cell preparation method interaction (P = 0.8) on cell area (Method 1: CC 99.7 ± 5.1, MGC 132.8 ± 5.8; Method 2: CC 221.9 ± 30.4, MGC 265.1 ± 48.5 µm(2)). The mean area of all cells combined was significantly less for cells prepared by Method 1 (116.2 ± 4.9 µm(2)) vs. Method 2 (243.5 ± 22.5 µm(2), P < 0.00005). Intracellular lipid level, however, was significantly altered by cell preparation method (P < 0.05; cell preparation method-cell type interaction, P < 0.00001). Initial lipid content was significantly lower in CC (74.5 ± 9.3) than MGC (136.3 ± 16.7 fluorescence/cell area, P < 0.00005), while subsequent lipid accumulation in vitro was significantly higher in CC (154.0 ± 9.1) than MGC (104.6 ± 9.9 fluorescence/cell area, P < 0.00001). The relatively diminished initial CC lipid content compared to subsequent CC lipid accumulation in vitro (P < 0.00001), and the opposite pattern for MGC (P < 0.05), significantly lowered the CC/MGC lipid ratio in Method 1 (0.55 ± 0.04) vs. Method 2 (1.58 ± 0.10, P < 0.00001). CONCLUSIONS: Differential uptake or utilization of lipid by CC and MGC occurs during oocyte maturation and steroidogenesis, respectively, with the amount of lipid present in ovarian cells a function of both the follicular microenvironment at the time of the oocyte retrieval and the capacity of these cells to accumulate lipid in vitro over time.