ABSTRACT: Heat stress (HS) can weaken the intestinal integrity and damage the intestinal barrier function of poultry, disrupting nutrient digestion and absorption. However, the underlying molecular mechanism is unclear. Our objective was to examine the gene expression profile of the jejunum by conducting transcriptomic analysis of heat-adapted and heat-sensitive breeder hens under acute HS (36 °C for a 6-h). Fifty 28-week-old breeder hens were raised individually in a cage and randomly assigned to heat-adapted and heat-sensitive groups (25 hens each). After exposure to acute HS for 6 hours, jejunal mucosa samples from the heat-adapted (HA group, n = 3) and heat-sensitive (HS group, n = 3) groups were selected for transcriptome analysis using RNA sequencing (RNA-seq). RNA-seq identified 284 differentially expressed genes, with 155 genes upregulated and 129 downregulated in the heat-sensitive group compared to the heat-adapted group. Gene ontology term (GO) analysis of the DEGs revealed significant enrichment in 555 GO terms. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway revealed 5 pathways were significantly enriched in upregulated DEGs, including the VEGF signaling pathway, MAPK signaling pathway, steroid biosynthesis, neuroactive ligand-receptor interaction, and cell cycle, and 1 pathway significantly enriched in downregulated DEGs, such as cell adhesion molecules. The protein-protein interaction (PPI) network identified PLK1, CDC7, CDC20, HSPA2, IL6, SLC22A19A, LBFABP, and SLC2A2 as key core nodes, which may play crucial roles in regulating the effects of HS on cell division, immune function, energy and lipid metabolism, and nutrient transport. The findings suggest that acute HS might affect cell division, immune function, energy and lipid metabolism, and organic acids and glucose transport mechanisms in the jejunal mucosa of breeder hens. The DEGs and pathways identified in this study will provide new insights to understand further the molecular mechanisms underlying HS responses in avian intestinal function, suggesting potential targets for nutritional or management strategies to mitigate its effects.
