Levels of steroidogenic acute regulatory protein and mitochondrial membrane potential in granulosa cells of older poor-responder women

Objective: To compare mitochondrial function in granulosa cells obtained from older (> 40 y) low-responder IVF patients with that of young (< 35 y) good-responder patients. Design: Prospective laboratory research. Setting: In vitro fertilization unit in a university hospital. Patient(s): Twenty patients undergoing IVF treatment cycles. Intervention(s): Ultrasound guided oocytes pick-up. Main Outcome Measure(s): Mitochondrial function examined by using JC-1 stain for the mitochondrial membrane potential in granulosa cells of both groups and Western blots for assaying and quantification of steroidogenic acute regulatory protein (StAR) and p450scc (side-chain cleavage). Result(s): The number of granulosa cells per follicle differed between the two groups, with fewer granulosa cells isolated in the older low-responder women, compared with in the young, normal responders who were the control women. Trypan blue-negative cells showed similar undisturbed mitochondrial membrane potential, and similar ratios of apoptotic granulosa cells were observed in the two groups. In addition, there was no difference in StAR and P450scc protein levels between the two groups. Conclusion(s): Our results demonstrate a significant decrease in the number of total aspirated granulosa cells per follicle in older, poor-responder women, which probably explains the reduced hormonal production by those follicles. However, those cells demonstrate normal mitochondrial membrane potential as well as similar levels of StAR, P450scc, and de novo steroid hormone synthesis in the two groups of patients. Our results do not support mitochondrial dysfunction as a main mechanism of reproductive aging. (Fertil Steril (R) 2009;91:220-5. (c) 2009 by American Society for Reproductive Medicine.)