Effects of quercetin supplementation on antioxidant capacity, inflammatory status, ovarian reserve and steroidogenesis in juvenile and reproductively aged rabbit does

Abstract

Nutritional strategies to reduce oxidative stress (OS) and to improve female reproductive performance include supplementation with flavonoids such as quercetin (QUR), that may modulate OS and ovarian function depending on age and reproductive status. To evaluate whether QUR supports the onset of reproductive life or alleviates age-related OS, juvenile rabbit females (J; 8 weeks of age) and adult rabbit does previously subjected to repeated semi-intensive cycles (A; 12-13.5 months-old) received oral QUR supplementation (300 mg/kg, JQ and AQ) or remained untreated (JC and AC) for 8 weeks. Serum TNF-α and IL-1β (ELISA), antioxidant capacity (FRAP) and malondialdehyde (MDA) levels (TBARS) were monitored at the beginning, midpoint, and end of the experiment. At the endpoint, body composition was evaluated bioelectrical impedance analysis (BIA). Following in vivo ovulation induction, ovaries and blood samples were collected 14 h post-ovulation. Ovarian reserve was assessed by follicle counting, serum anti-Müllerian hormone (AMH) quantification (ELISA), and ovarian immunohistochemistry. Follicular apoptosis was evaluated by TUNEL assay, and steroidogenesis analysing serum oestradiol (E2), progesterone (P4) levels, and E2/P4 ratio (ELISA). QUR did not affect OS or inflammatory markers. MDA concentrations decreased over time in adults but remained unchanged in juveniles (p < 0.05) and antioxidant capacity increased during the first 4 weeks in adults and decreased in juveniles (p < 0.05). Age affected ovarian weight, P4 levels and P4/ E2 ratio (p < 0.05), with higher values in adults regardless of treatment. Follicular reserve declined with age (p < 0.05), although serum AMH levels and ovarian AMH immunoexpression were unchanged. In juveniles, QUR increased body energy content and serum P4 concentrations. No other ovarian parameters differed among groups or ages. In conclusion, under non-productive conditions, females showed no OS or inflammation compromising follicular reserve. QUR modulated energy reserves and luteal function in juveniles at the onset of reproductive life. Overall, oxidative status appears to be driven primarily by productive cycles rather than flavonoid supplementation.