Park So-Young, Kim Yong-Woon, Kim Ji-Eun, Kim Jong-Yeon
Department of Physiology, College of Medicine, Yeungnam University, Daegu, South Korea.
Life Sci. 2006 Nov 2;79(23):2228-33. doi: 10.1016/j.lfs.2006.07.014. Epub 2006 Jul 21.
In this study, to determine if age associated changes in fat metabolism in skeletal muscle and liver were related with sympathetic activity, we measured sympathetic activity and palmitate oxidation rate, carnitine palmitoyltransferase-1 (CPT-1) activity, and triglyceride concentration in skeletal muscle and liver of rats at 8, 30 and 60 weeks of age. Body weight, intra-abdominal percent of fat mass, and plasma level of insulin, leptin, and triglyceride were all significantly increased with age. Tissue triglyceride concentration was increased with age in liver and skeletal muscle. The palmitate oxidation rate in liver and skeletal muscle was reduced with age in rats and inversely correlated with tissue triglyceride concentration. CPT-1 activity was not altered with age. Plasma catecholamine concentration and sympathetic activity, as measured by spectral analysis of heart rate variability, were increased with age. Plasma norepinephrine or epinephrine and tissue triglyceride had a positive correlation in liver and skeletal muscle. Plasma norepinephrine or epinephrine to tissue triglyceride ratio was similar according to age. In summary, in spite of increased sympathetic activity with age, the tissue triglyceride concentration was increased. Increased sympathetic activity may be the compensatory response and the reduced capacity of fatty acid oxidation is a main cause of obesity.
在本研究中，为了确定骨骼肌和肝脏中与年龄相关的脂肪代谢变化是否与交感神经活动有关，我们测量了8周、30周和60周龄大鼠骨骼肌和肝脏中的交感神经活动、棕榈酸氧化率、肉碱棕榈酰转移酶-1（CPT-1）活性以及甘油三酯浓度。体重、腹部脂肪质量百分比以及胰岛素、瘦素和甘油三酯的血浆水平均随年龄显著增加。肝脏和骨骼肌中的组织甘油三酯浓度随年龄增加。大鼠肝脏和骨骼肌中的棕榈酸氧化率随年龄降低，且与组织甘油三酯浓度呈负相关。CPT-1活性不随年龄改变。通过心率变异性频谱分析测量的血浆儿茶酚胺浓度和交感神经活动随年龄增加。肝脏和骨骼肌中血浆去甲肾上腺素或肾上腺素与组织甘油三酯呈正相关。血浆去甲肾上腺素或肾上腺素与组织甘油三酯的比值随年龄相似。总之，尽管交感神经活动随年龄增加，但组织甘油三酯浓度仍升高。交感神经活动增加可能是一种代偿反应，而脂肪酸氧化能力降低是肥胖的主要原因。
