Effects of spermidine-rich diet on follicle development and steroidogenesis in Sichuan white geese.

Polyamines have been reported to play a role in the regulation of follicular development and steroidogenesis, the underlying mechanisms remain unclear. This study examined the effects of spermidine-enriched diets on ovarian follicle development and steroid hormone synthesis in Sichuan white geese. Forty healthy female Sichuan white geese were randomly assigned to five groups(Con, 5SPG, 10SPG, 5SPD, and 10SPD). The Con group were provided with basal diet, while the 5SPG and 10SPG groups were fed wheat germ feed containing 5 mg/kg or 10 mg/kg spermidine, respectively. Similarly, the 5SPD and 10SPD groups received basal diets containing 5 mg/kg and 10 mg/kg pure spermidine, respectively. In the 5SPG group, ovarian spermidine and putrescine concentrations, along with serum and follicular E2 and P4 levels, increased significantly (P < 0.05). Serum malondialdehyde (MDA) level decreased, whereas BCL-2 gene expression was significantly elevated compared with the control group (P < 0.05). Furthermore, the expression of StAR and 3β-HSD in yellow follicles and of 17β-HSD and CYP17A1 in white follicles was significantly upregulated in the 5SPG group (P < 0.05). Conversely, the 10SPD group exhibited severe follicular damage, increased numbers of white follicles (P < 0.05), and reduced polyamine and E2 concentrations in prehierarchical follicles (P < 0.05). Additionally, the expression of steroidogenesis-related genes was significantly reduced (P < 0.05), whereas ovarian MDA concentrations and Caspase-3 and Bax expression were significantly upregulated (P < 0.05). Collectively, these results indicate that a wheat germ diet containing 5 mg/kg spermidine enhanced ovarian antioxidant capacity, modulated steroid hormone levels through the regulation of steroidogenesis-related gene expression, and promoted follicular development in Sichuan white geese.