Anti-injury Mechanisms in the Liver and its Molecular Regulatory Networks of the Hezuo Pig under Cold Stress

Background Cold stress is a critical environmental factor that adversely affects the production performance and health status of livestock and poultry. To explore the physiological adaptation mechanisms underlying cold resistance differences among pig breeds, this study employed cold-resistant Hezuo pigs and cold-sensitive Bama pigs as models, systematically comparing liver injury phenotypes and molecular response characteristics after 5, 10, 15, and 20 days of cold exposure at -15°C. Results The results demonstrated that: 1) After 20 days of cold stress, serum liver function markers (ALT, AST, LDH) in Bama pigs were significantly elevated ( P  < 0.05), while remaining stable in Tibetan pigs. 2) Histological analysis revealed that the α-SMA-positive area in Bama pig livers increased significantly with prolonged cold exposure ( P  < 0.05), exceeding that of Tibetan pigs from day 15 onward. 3) Morphological observations showed that Bama pigs developed ear frostbite and liver surface congestion after 15 days of cold stress, whereas Tibetan pigs maintained normal appearances. 4) Ultrastructural analysis indicated mitochondrial swelling and nuclear membrane abnormalities in Bama pig hepatocytes, while Tibetan pigs exhibited relatively normal cellular structures. 5) High-throughput sequencing identified 1,307 differentially expressed mRNAs (DEmRNAs), 320 DElncRNAs, 1,299 DEcircRNAs, and 162 DEmiRNAs in liver tissues between the two breeds under cold stress. Functional enrichment analysis revealed that in Bama pigs, DEmRNAs were primarily involved in metabolic processes, oxidative stress, and liver fibrosis-related pathways, whereas in Tibetan pigs they were enriched in metabolic and antioxidant-related biological processes. RT-qPCR validation confirmed the accuracy and reliability of the sequencing results. Finally, we constructed ceRNA regulatory networks to illustrate their potential roles in the anti-damage mechanisms of Tibetan pig livers. Conclusions Collectively, Bama pigs exhibited greater sensitivity to cold stress with more severe liver damage, while Tibetan pigs demonstrated superior cold tolerance. Three key ceRNA networks were identified as potentially crucial in the cold resistance mechanisms of Tibetan pigs: (circ_023716/008930/007918)—ssc-miR-29b—CYP2A19; circ_000082—ssc-miR-204—(P2RY13/ADORA2B); and MSTRG.7463.1—ssc-miR-204—P2RY13. This study systematically elucidates the phenotypic characteristics and molecular basis of cold adaptation in Tibetan pigs, providing not only novel insights into animal environmental adaptation evolution but also important theoretical foundations and candidate molecular targets for livestock stress-resistant breeding.