Effects of Cold Stress on the Morphology and Thermogenic Capacity of Adipose Tissue in Various Anatomical Depots of Min pigs

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.