Age-related variations in follicular apolipoproteins may influence human oocyte maturation and fertility potential

Objective: To investigate involvement of specific apolipoproteins in the process of human oocyte maturation and age-related infertility as molecular constituents of follicular fluid. Design: Laboratory-based observational study. Setting: Basic science laboratory at a large academic institution. Patient(s): Follicular fluid obtained from healthy women aged 18 to 45 years undergoing in vitro fertilization for unexplained infertility, ovulatory dysfunction, tubal disease, male factor infertility, or oocyte donation. Intervention(s): None. Main Outcome Measure(s): Specific concentration of apolipoproteins and content of lipoprotein particles in follicular fluid and blood plasma as related to reproductive aging. Result(s): We registered a decline of follicular apolipoprotein A1 (Apo A1) and apolipoprotein CII (Apo CII) and an increase of the apolipoprotein E (Apo E) with age, which parallels a lower number of retrieved mature oocytes in older women. Follicular apolipoprotein A1, apolipoprotein B (Apo B), apolipoprotein E, and apolipoprotein C II are present in diverse heterogeneous complexes including very-low-density lipoproteins (VLDL), intermediate-low-density lipoproteins (IDL), low-density lipoproteins (LDL), and high-density lipoproteins (HDL) that vary with patient age and differ from the blood plasma lipoprotein complexes. Conclusion(s): Age-related variation in follicular apolipoprotein content and distribution in the cholesterol particles may be associated with the decrease in production of mature oocytes and the age-related decline in fertility potential. (Fertil Steril (R) 2010; 93: 2354-61. (C)2010 by American Society for Reproductive Medicine.)