Dietary inulin supplementation in early gestation regulates uterine fluid exosomes and angiogenesis to improve embryo implantation in sows

Abstract

Background: Embryo implantation in early gestation is crucial for reproductive success, while dietary fiber plays a key role in regulating sow fertility. However, the underlying mechanisms remain unclear. This study explores the influence of dietary inulin on embryonic implantation using a sow model. Sows were fed a diet supplemented with 11 g/kg of inulin during early gestation and were slaughtered on gestation day 19 (G19). Uterine fluid exosomes (UFEs) and endometrial tissues were collected for high-throughput sequencing and for analysis of the expression of angiogenesis-related genes and proteins, respectively. Furthermore, UFEs obtained from slaughtered sows were injected into G19 sows to investigate the effects on reproduction and angiogenesis. Results: The results showed that inulin significantly increased the number of blood vessels in the endometrium and expression of the angiogenesis-related proteins MMP2 and ANGPT1 in G19 sows (P < 0.05). Bioinformatics analysis revealed that inulin significantly downregulated miRNAs associated with angiogenesis inhibition in UFEs, while upregulating miRNAs related to trophoblast physiological activities and regulation of the uterine fluid microenvironment (P < 0.05). Furthermore, intravenous injection of G19 sows with UFEs from sows fed a diet containing inulin had significantly promoted vascular formation in the endometrium and embryos, and increased the number of live embryos on gestation day 28 (G28) (P < 0.05). Additionally, the mRNA expression levels of MMP2, ANGPT1, and VEGF in the placentas of sows were significantly elevated on G28 and at farrowing in the UFEs injection group (P < 0.05). Conclusion: Dietary supplementation with inulin during early gestation in sows promoted embryo implantation by regulating angiogenesis at the maternal–fetal interface through the modulation of miRNA expression in UFEs. These findings provide a theoretical reference for the application of dietary fiber in sow nutrition.