High-altitude hypoxia exposure alters follicular metabolome and oocyte developmental potential in women

To explore the effects of high-altitude hypoxia on the microenvironment of oocyte development and fertilization potential, we compared the metabolomic patterns of follicular fluid from women living in different altitude areas and traced their oocyte maturation and subsequent development.

A total of 315 clinical cases were collected and divided into three groups according to their residence altitudes: 138 cases in low-altitude (< 2300 m) group, 100 cases in middle-altitude (2300-2800 m) group and 77 cases in high-altitude (> 2800 m) group. The clinical outcomes were statistically estimated, including hormonal level, oocyte maturation, in vitro fertilization, and embryo development. Meanwhile, a metabolomic analysis was performed on the follicular fluid of women from different groups using ultra-high-performance liquid chromatography and high-resolution mass spectrometry and differential metabolites were analyzed through the KEGG pathway.

The clinical data indicated that the physical condition and reproductive hormone secretion were similar among different groups. Although personalized gonadotropin-releasing hormone strategies were applied, the numbers of antral follicles and obtained oocytes were not impacted by the residence altitude change. In in vitro culture, the maturing rate, fertility rate and cleavage rate of high-altitude group were compared with the other groups. However, the rates of high-quality embryo, formative blastocyst, and available blastocyst were gradually decreased with the rise of residence altitude. Metabolome analysis identified 1193 metabolites in female follicular fluid. Differential analysis indicated that metabolic components in follicular fluid were remarkably changed with the elevation of residence altitude. These differential metabolites were closely related with amino acid metabolism, protein digestion and absorption, oocyte meiosis and steroid biosynthesis.

The residence altitude alters the microenvironment of follicular fluid, which could damage the oocyte developmental potential. This study provides diagnostic basis and therapeutic targets for research on female oocyte and embryo development.