Clarke L, Heasman L, Firth K, Symonds M E
School of Animal and Microbial Sciences, University of Reading, United Kingdom.
Am J Physiol. 1997 Jun;272(6 Pt 2):R1931-9. doi: 10.1152/ajpregu.1997.272.6.R1931.
We examined the effect of route of delivery on brown adipose tissue (BAT) function and thermoregulation in lambs born either vaginally at term or by cesarean section close to term. Immediately after birth, lambs were placed in a warm (30 degrees C; WD) or cool (15 degrees C; CD) ambient temperature, and measurements of colonic temperature, plus heat production (i.e., oxygen consumption and carbon dioxide production), were recorded for 6 h. Over the first 30 min of life, colonic temperature remained constant in vaginally delivered lambs and was lower in the WD group. Following cesarean section delivery, colonic temperature declined rapidly, a response that was greater in the CD group. Cesarean section-delivered lambs had an increased reliance on shivering thermogenesis and restored colonic temperature after 2 h, and by 6 h these parameters were higher than in lambs born vaginally. Irrespective of delivery, temperature, plasma thyroid hormone concentrations and norepinephrine content of BAT were lower in lambs born by cesarean section compared with those born vaginally. Plasma cortisol concentrations and epinephrine content of BAT were greater in lambs born by cesarean section. The amount of uncoupling protein and level of guanosine 5'-diphosphate binding in BAT were higher in vaginally delivered than in cesarean section-delivered lambs, and for each group mean values were greater for CD than WD lambs. Cesarean section delivery results in altered thyroidal, adrenal, and sympathetic activity, which appears to have a marked influence on BAT function, thereby contributing to distinct differences in thermoregulation compared with lambs born vaginally.
我们研究了分娩方式对足月顺产或接近足月剖宫产出生的羔羊棕色脂肪组织（BAT）功能及体温调节的影响。出生后立即将羔羊置于温暖（30摄氏度；WD）或凉爽（15摄氏度；CD）的环境温度中，并记录结肠温度以及产热量（即耗氧量和二氧化碳生成量），持续6小时。在出生后的最初30分钟内，顺产羔羊的结肠温度保持恒定，且WD组的温度较低。剖宫产出生后，结肠温度迅速下降，CD组的这种反应更为明显。剖宫产出生的羔羊对颤抖产热的依赖增加，2小时后结肠温度恢复，到6小时时这些参数高于顺产出生的羔羊。无论分娩方式如何，剖宫产出生的羔羊与顺产出生的羔羊相比，其BAT的甲状腺激素浓度和去甲肾上腺素含量较低。剖宫产出生的羔羊BAT的血浆皮质醇浓度和肾上腺素含量较高。顺产羔羊BAT中的解偶联蛋白量和鸟苷5'-二磷酸结合水平高于剖宫产出生的羔羊，且每组中CD组羔羊的平均值高于WD组。剖宫产导致甲状腺、肾上腺和交感神经活动改变，这似乎对BAT功能有显著影响，从而导致与顺产出生的羔羊相比，体温调节存在明显差异。
