Karlsson A K, Elam M, Friberg P, Biering-Sörensen F, Sullivan L, Lönnroth P
Department of Clinical Neuroscience (Spinal Unit and Department of Clinical Neurophysiology), Rigshospitalet, University of Copenhagen, Denmark.
Metabolism. 1997 Apr;46(4):388-94. doi: 10.1016/s0026-0495(97)90053-6.
To evaluate the regulation of lipolysis by the sympathetic nervous system, eight spinal cord-injured (SCI) subjects with a lesion above T5 resulting in a decentralization of the lower-body sympathetic nervous system and adrenal medulla (age, 36 +/- 2 years; weight, 82 +/- 5 kg; body fat mass, 26.8 +/- 3.0 kg; all mean +/- SE) and nine control subjects (age, 33 +/- 2; weight, 80 +/- 3; NS; body fat mass, 16.1 +/- 1.5 kg; P < .01) were investigated after fasting overnight. Each subject was studied with subcutaneous microdialysis and 133Xe-clearance adipose tissue blood flow (ATBF) in the umbilical and clavicular regions during postabsorptive rest and after sympathoexcitatory stimulation by means of mental stress and isometric handgrip exercise. SCI subjects had an increased body fat mass, hyperinsulinemia, and an elevated lipolytic rate at rest compared with control subjects. ATBF and lipolysis were activated to a normal extent following mental stress and isometric handgrip exercise in the umbilical region in control subjects. ATBF was increased in tissue above but not below the lesion level in SCI subjects following mental stress. Glycerol release was not different between groups in either tissue region despite significantly lower noradrenaline and adrenaline levels in SCI subjects. This finding argues against a significant adrenergic control of the lipolytic rate at rest. Furthermore, the small differences in stimulated glycerol release between groups, as well as the increased plasma glycerol levels in SCI subjects, cast doubt on the view that interruption of adrenergic activity below the lesion is the sole mechanism underlying the increased body fat mass in SCI subjects.
为评估交感神经系统对脂肪分解的调节作用，对8名脊髓损伤（SCI）受试者和9名对照受试者进行了研究。8名SCI受试者的损伤位于T5以上，导致下半身交感神经系统和肾上腺髓质去神经支配（年龄36±2岁；体重82±5 kg；体脂量26.8±3.0 kg；均为平均值±标准误），9名对照受试者（年龄33±2岁；体重80±3 kg；无显著性差异；体脂量16.1±1.5 kg；P<0.01），所有受试者均过夜禁食。在吸收后静息状态以及通过精神应激和等长握力运动进行交感神经兴奋刺激后，采用皮下微透析和133Xe清除法测量脐部和锁骨区域的脂肪组织血流量（ATBF），对每位受试者进行研究。与对照受试者相比，SCI受试者的体脂量增加、存在高胰岛素血症，且静息时脂肪分解率升高。在对照受试者中，精神应激和等长握力运动后，脐部区域的ATBF和脂肪分解被激活至正常程度。精神应激后，SCI受试者损伤水平以上而非以下的组织中ATBF增加。尽管SCI受试者的去甲肾上腺素和肾上腺素水平显著降低，但两组在任一组织区域的甘油释放均无差异。这一发现反对静息时脂肪分解率受显著肾上腺素能控制的观点。此外，两组间刺激后甘油释放的微小差异，以及SCI受试者血浆甘油水平的升高，使人怀疑损伤以下肾上腺素能活性中断是SCI受试者体脂量增加的唯一潜在机制这一观点。
