Association of lower plasma estradiol levels and low expression of scavenger receptor class B, type I in infertile women

ObjectiveTo determine the expression of the scavenger receptor, class B, type I (SR-BI) in human granulosa cells.DesignProspective cohort analysis.SettingTertiary academic university hospital.Patient(s)Women undergoing IVF treatment.Intervention(s)Granulosa cells were isolated from oocyte retrievals.Main Outcome Measure(s)Total RNA and cell lysates were isolated from the granulosa cells, and SR-BI RNA and protein expression were quantified by real-time polymerase chain reaction and western blotting, respectively. Baseline and peak E2 levels were drawn before IVF treatment and before hCG stimulation.Result(s)The expression of SR-BI RNA and protein were positively correlated. The prevalence of low SR-BI RNA expression (defined as below 25th percentile) was 26%, whereas the prevalence of high SR-BI expression (defined as above 75th percentile) was 24%. Expression of SR-BI RNA was not correlated with body mass index, age, race or ethnicity, primary diagnosis of infertility, or pregnancy outcomes. However, baseline and peak E2 levels were significantly lower in subjects with low SR-BI RNA expression as compared with subjects with high SR-BI expression (P<.04). There was a positive correlation between the number of retrieved (P<.02) and fertilized oocytes (P<.002) and SR-BI RNA levels.Conclusion(s)Scavenger receptor–BI is expressed in human granulosa cells. Subjects with low SR-BI expression had lower baseline and peak E2 levels and lower number of retrieved and fertilized oocytes.