P-154 growth hormone supplementation decline quality of maternally aged oocytes via reducing aneuploidy

Abstract

Abstract Study question Does growth hormone (GH) supplementation ameliorate the quality of oocytes in aged mice via reducing aneuploidy? Summary answer Daily injections of growth hormone for 2 months improve the age-related decline in ovarian reserve, and promote oocyte quality by reducing the aneuploidy rate. What is known already Women of advanced maternal age, particular over 35 years, could consequently bear poor quality oocytes, which are mainly caused by chromosomal aneuploidy. Age-related decline in GH levels may be related to the insufficient reproductive potential in women of advanced maternal age. To date, the role of GH in in vitro fertilization remains controversial. GH has been reported to affect oocyte quality, and studies in vivo have shown that intraperitoneal administration of GH reduces the occurrence rate of spindle/chromosome defects. Study design, size, duration The young (6-week-old) and aged (8-month-old) C57BL/6J mice were used in the study. In the in vivo experiment, aged mice were intraperitoneally injected daily with GH (1.6 mg/kg body weight, n = 85) or the equivalent volume of NS (n = 81) for consecutive for two months. In the in vitro experiment, GV oocytes from aged mice were treated with GH (Gene Science Pharmaceuticals, Changchun, China) (200ng/ml) in M16 medium for 14∼16 hours. Participants/materials, setting, methods We analyzed the number of oocytes and hormone levels to assess ovarian reserve, by immunohistochemistry and ELISA methods. The expression of GHR was measured by real-time quantitative RT-PCR and immunofluorescence. Time–lapse incubator was utilized to record the developmental potential of oocytes and embryos. Immunofluorescence was performed to assess parameters of oocyte quality (mitochondrial functions, ROS level, spindle/chromosome defects, and DNA damage). Chromosome spread and single-cell DNA sequencing were used to analyze chromosome aneuploidy rate. Main results and the role of chance The expression of GHR decreased in aged oocyte (21.68±1.08) and increased after GH treatment(30.64±0.70, P < 0.001). GH ameliorated decline in ovarian reserve of aged mice, with increased ovarian index (0.040%±0.0031 vs 0.023%±0.0019, P < 0.01), number of preantral follicles (7.33±0.89 vs 4.12±0.58, P < 0.05) and antral follicles (8.67±1.2 vs 3.33±0.88, P < 0.05) compared to the aged controls, but no other hormonal differences were detected. After GH supplementation, aged oocyte showed better quality and developmental potential, including restored mitochondrial functions (P < 0.05) and decreased ROS level (19.83±1.50 vs 23.6±1.72, P < 0.05). As expected, GH effectively promoted the fertilization rate (39.9%±1.10 vs 14.4%±0.62, P < 0.001) and early embryo development (P < 0.01). In addition, the spindle/chromosome defects (31.6%±2.12 vs 48.9%±1.83, P < 0.01), DNA damage (16.37±1.76 vs 49.35±2.52, P < 0.001) and aneuploidy rate (21.5%±1.61 vs 34.6%±1.84, P < 0.01) were lower in GH group than that in control group. Overall, GH treatment restored age-related decline in ovarian reserve, and decreased the occurrence rate of aneuploidy caused by spindle/chromosome defects, inducing a better oocyte quality in aged mice. Limitations, reasons for caution The molecular and mechanism of GH to regulate spindle/chromosome function remains to be determined. Besides, future work should be extended to human oocyte to determine whether this mechanism is conserved between mice and humans. Wider implications of the findings Our work expounds a theoretical basis for application of GH to improve the fertility of aged women. Besides, the results also feed new ideas for the prevention and treatment of oocyte quality decline in assisted reproductive technology. Trial registration number not applicable