Alterations of Growth Performance, Blood Parameters, and Antioxidant Function of Brown Adipose Tissue in Mice Exposed to Cold

Cold exposure is an unavoidable stressor in cold regions, leading to growth retardation, oxidative damage, and endocrine disruption. This study investigated changes in blood parameters and antioxidant function in the brown adipose tissue (BAT) of mice exposed to cold. Sixteen naturally mated female mice (aged 70 days) were selected and divided into a control group (CON, n = 8, 25 ± 1 °C) and a cold exposure group (CE, n = 8, 4 ± 1 °C). Each pregnant female gave birth to approximately 12 pups, and the litter (dams and pups co-housed) served as the independent experimental unit, with both euthanized for sampling when the pups reached 20 days of age. Results showed that cold exposure increased ADFI and ADG but decreased the feed conversion rate (FCR) in lactating mice. It also decreased platelet count (PLT) and mean corpuscular hemoglobin concentration (MCHC), elevated lactate dehydrogenase (LDH) activity, and decreased TG and non-esterified fatty acid (NEFA) levels. Hormonal changes included increased adrenocorticotropic hormone (ACTH), apelin 12 (AP12), INS, NE, decreased cortisol (COR), LEP, and thyroid-stimulating hormone (TSH). In pups, cold exposure inhibited growth, reduced PLT, plateletcrit (PCT), red blood cells (RBC), and hemoglobin (HGB), altered lipid profiles, and induced hormonal shifts. Notably, cold exposure enhanced the BAT antioxidant capacity in pups, increasing the total antioxidant capacity (T-AOC) and antioxidant enzyme activities, as supported by gene expression. These findings suggest that, despite growth suppression, mice maintain homeostasis by modulating blood parameters and enhancing BAT antioxidant function to mitigate cold-induced damage.