Objective To investigate the effect of galacto-oligosaccharides on the thermogenic function of brown adipose tissue in chronic cold-exposed mice and its possible molecular mechanism. Methods Eight-week-old male C57BL/6J mice were randomly divided, based on body weight, into a room-temperature control group (RT_Con), a cold-control group (Co_Con), and a cold-Gos group (Co_Gos), with 11 mice per group. The RT_Con group was housed under normal room-temperature conditions, while the Co_Con and Co_Gos groups were placed in a cold simulation chamber at 4℃ for continuous exposure for 14 days. The Co_Gos group received a daily intragastric administration of Gos at 1500 mg/kg body weight (gavage volume 10 ml/kg, concentration 150 mg/ml), whereas the RT_Con and Co_Con groups received an equal volume of distilled water by gavage. During the experiment, food and water intakes, body weight, rectal temperature, and four-limb grip strength were monitored. After the experiment, the interscapular BAT was dissected, weighed, and processed for hematoxylin-eosin (HE) staining to observe morphological changes in adipocyte lipid droplets. The protein contents of adenylyl cyclase (AC), protein kinase A (PKA), hormone-sensitive lipase (HSL), lipoprotein lipase (LPL), adipose triglyceride lipase (ATGL), and the key thermogenic proteins peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α) and uncoupling protein 1 (UCP1), as well as the concentration of cyclic adenosine monophosphate (cAMP), in BAT were determined by enzyme-linked immunosorbent assay (ELISA). The mRNA expression levels of Adcy3, Adcy5, Adcy6, Hsl, Lpl, Atgl, Pgc-1α, Ucp1, Prdm16, and Pparg in BAT were detected by real-time quantitative PCR (RT-qPCR). Protein expression levels of UCP1 in BAT were measured by Western blot and immunohistochemistry (IHC). Results Compared with the RT_Con group, cold exposure resulted in decreased body weight, reduced rectal temperature, and weakened four-limb grip strength in mice (P < 0.05). BAT lipid droplet areas were significantly reduced, and the expressions of the AC/cAMP/PKA signaling pathway molecules, as well as UCP1 and PGC-1α, were upregulated (P<0.05). Compared with the Co_Con group, Gos intervention led to a recovery in rectal temperature, enhanced four-limb grip strength, increased BAT weight and relative BAT weight, and further reduction in lipid droplet area (P<0.05) . The protein expressions of AC, PKA, HSL, LPL, UCP1 and PGC-1α, as well as the cAMP concentration were significantly upregulated (P < 0.05), and the mRNA levels of Adcy3, Adcy6, Lpl, Ucp1, Pgc-1α, and Pparg were also significantly elevated (P<0.05). Conclusion Galacto-oligosaccharide intervention may promote BAT thermogenic function and improve cold adaptation capacity in chronic cold-exposed mice, possibly by activating the AC/cAMP/PKA signaling pathway in BAT, upregulating the expression of the key thermogenic proteins UCP1 and PGC-1α, and enhancing lipolysis.
Key words
cold exposure /
mice /
galacto-oligosaccharides /
brown adipose tissue /
thermogenesis /
uncoupling protein 1
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