Integrated Metabolomic and Transcriptomic Analysis Decodes Heat Stress-Induced Metabolic Shifts in Gilt Granulosa Cells

While previous studies have extensively demonstrated that summer heat stress (HS) impairs oocyte quality via follicular granulosa cell (GC) mediation, the molecular mechanisms underlying HS-induced GC-mediated oocyte damage-particularly at the multi-omics level-remain poorly understood. This study integrated metabolomic and transcriptomic analyses of GCs from gilts under seasonal thermal stress (winter CON vs. summer HS) to elucidate GC-mediated regulatory networks affecting oocyte quality. Non-targeted metabolomics identified 45 differentially accumulated metabolites (DAMs, <i>p</i> < 0.05), with 69% being lipids/lipid-like molecules enriched in pathways such as glycerophospholipid metabolism, choline metabolism, linoleic acid metabolism, the adipocytokine signaling pathway, and the sphingolipid signaling pathway. Parallel transcriptomics revealed 9085 differentially expressed genes (DEGs, <i>Padj</i> < 0.05), of which the predominant genes were associated with lipid metabolism, hormone synthesis, and cellular senescence pathways. Cross-omics integration highlighted significant correlations between DAMs and DEGs, particularly for lysoPC(20:4) and 1-hexadecyl-2-eicosatrienoyl-sn-glycero-3-phosphocholine, which showed co-regulation with 69 and 48 genes, respectively. Notably, candidate genes like <i>TMEM94</i>, <i>SLIT3</i>, <i>DACT3</i>, and <i>CEBPD</i>, were identified as key regulators of GCs metabolic reprogramming. This study demonstrates for the first time that in vivo HS compromises oocyte developmental competence by disrupting the GC metabolic activities, particularly through lipid metabolism and associated pathways. The identified metabolic signatures and regulatory genes offer mechanistic insights into seasonal infertility and potential biomarkers for thermo-protective strategies in swine reproduction.