After exposure to cold stress, animals enhance the production of beige adipocytes and expedite thermogenesis, leading to improved metabolic health. Although brown adipose tissue in rodents is primarily induced by β3-adrenergic receptor (ADRB3) stimulation, the activation of major β-adrenergic receptors (ADRBs) in pigs has been a topic of debate. To address this, we developed overexpression vectors for ADRB1, ADRB2, and ADRB3 and silenced the expression of these receptors to observe their effects on the adipogenic differentiation stages of porcine preadipocytes. Our investigation revealed that cold stress triggers the transformation of subcutaneous white adipose tissue to beige adipose tissue in pigs by modulating adrenergic receptor levels. Meanwhile, we found that ADRB3 promotes the transformation of white adipocytes into beige adipocytes. Notably, ADRB3 enhances the expression of beige adipose tissue marker genes, consequently influencing cellular respiration and metabolism by regulating lipolysis and mitochondrial expression. Therefore, ADRB3 may serve as a pivotal gene in animal husbandry and contribute to the improvement of cold intolerance in piglets.

The original purpose of this study was to compare human and pig scRNA-seq data to determine why pigs do not have brown adipocytes. However, during the experiment, we identified brown adipocytes in pigs. Therefore, we aimed to confirm that these adipocytes were brown adipocytes via a comparative analysis using typical mouse brown adipose tissue sections. We found that swine brown adipocytes were distributed in an island-like pattern, with three typical characteristics: (1) numerous mitochondria and small lipid droplets, (2) a cellular volume smaller than that of white adipocytes, and (3) expression of specific marker genes (EBF2 and ATP2B4). The expression levels of the thermogenesis-related genes UCP2/3 were not significantly increased. Thus, we conducted ceRNA network analysis, revealing that high expression of the key microRNA miR-10383 increased the thermogenic efficiency of UCP3 in the cold exposure group. In addition, the epigenetic memory of UCP3 was disrupted. Chromatin accessibility and Whole-Transcriptome Sequencing of Groin Adiposesibility results revealed peaks in the promoter regions of the UCP2/3 genes. In our discussion of the study’s limitations, we explain how to repeat the experiment to significantly increase the UCP2/3 protein content. This study fills a research gap regarding brown fat in pigs and can provide a reference for future studies on fat metabolism.

To investigate the response mechanism of cold-resistant Enshi black pig breeds under cold stress, nine Enshi black pigs were randomly divided into three groups with three pigs in each: a control group (18 ± 2 °C for 58 d), a cold-stress-acclimated group (3 to 8 °C to −17 to −21 °C for 58 d), and an acute cold stress group (−17 to −21 °C for 3 d). RNA-seq technology was used to analyze mRNA and lncRNA expression patterns in subcutaneous adipose tissue under cold stress. The results showed that, under acute cold stress, many metabolic pathways were activated, including those involved in rapid energy supply (e.g., the citric acid cycle/TCA cycle, fatty acid degradation and metabolism, and glycolysis/gluconeogenesis), signal transduction pathways (e.g., PI3K Akt, MAPK, PPAR, HIF-1, mTOR, and FoxO), and immune and cellular homeostasis pathways (chemokine signaling pathway, T cell receptor signaling, Toll-like receptor signaling, and apoptosis and autophagy regulation). Under cold stress acclimation, metabolic regulatory pathways (e.g., AMPK, mTOR, FoxO, HIF-1, glycolysis/gluconeogenesis, and fatty acid degradation), immune and inflammatory regulatory pathways (Toll-like receptors, NOD like receptors, and T/B cell receptor signaling pathways), and signal transduction and cell homeostasis pathways (MAPK, PI3K Akt, NF-κB, Notch signaling pathways, apoptosis, and autophagy regulation) were continuously activated to ensure the stability of adipose tissue structure and function. Acute cold stress activated more pathways than cold stress acclimation, but both led to significant changes in energy metabolism. The results identified the molecular regulatory mechanisms of adipose tissue under cold stress, providing a basis for the subsequent breeding of new cold-resistant pig breeds.

Cold exposure is a major physiological stimulus that promotes adipose tissue browning and enhances thermogenic capacity. As a cold-tolerant breed, Min pigs may rely on distinct adaptive mechanisms in adipose tissues, but how different adipose depots respond to cold stress remains unclear. This study systematically examines how cold exposure affects adipose tissue morphology, thermogenic gene expression, and the differentiation potential of preadipocytes derived from four adipose depots—cervical, axillary, perirenal, and inguinal—in Min pigs. Adipose tissues from the four depots were collected and analyzed using infrared thermography, histological staining, scanning electron microscopy, real-time quantitative PCR, Western blotting and in vitro differentiation assays. The results demonstrated that cold stress induced depot-specific remodeling patterns. Infrared thermography showed that the subcutaneous adipose depots including inguinal and axillary depots maintained relatively higher surface temperatures following cold exposure. Histological and ultrastructural analyses revealed typical beige-like characteristics in inguinal depots, including the accumulation of small lipid droplets, whereas changes in other depots were minimal. Molecular analyses further confirmed this heterogeneity: inguinal depots exhibited the strongest beiging response, characterized by significant upregulation of key thermogenic markers (PGC1α, UCP3, and DIO2) and lipolytic genes (HSL and ATGL) at the mRNA and/or protein levels. In contrast, visceral adipose depots showed weak or suppressed thermogenic activation. In vitro differentiation assays demonstrated that preadipocytes isolated from inguinal depot had the strongest beiging potential, forming tightly packed small lipid droplets and markedly increasing the expression of beige adipose-related genes upon induction. In conclusion, this study demonstrates that cold stress induces distinct beige remodeling across adipose depots in Min pigs, with the inguinal depot exhibiting the strongest thermogenic response and differentiation potential at morphological, molecular, and cellular levels. These findings identify the inguinal depot as a key site for adaptive thermogenesis and provide novel insights into adipose tissue remodeling and environmental adaptation in large mammals.