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目的应用功能核磁共振观察不同体重者下丘脑对口服葡萄糖耐量试验的反应,揭示不同体重者下丘脑中枢糖代谢调节的敏感性与代谢紊乱发生的关系。方法分别采集10名正常体重者与10名肥胖者口服75克葡萄糖后的下丘脑功能磁共振图像数据以及腹部解剖结构图像数据;同时测定受试者的空腹血糖、游离脂肪酸及相应激素水平。应用自行建立的灰度平均值方法进行图像分析处理;同时进行受试者脑功能信号参数与血生化指标水平、相应激素水平及腹部脂肪含量的相关分析。结果不同体重者口服葡萄糖后在下丘脑部位均出现一过性的抑制反应。但肥胖者此抑制反应出现的时间较正常体重者明显延迟;抑制反应强度明显低于正常体重者;抑制反应恢复时间也明显迟于正常体重者。受试者的空腹血浆胰岛素及其痩素水平与其下丘脑抑制信号恢复到基线的时间有关联;受试者的腹部脂肪含量与其下丘脑抑制信号恢复到基线的时间亦有关联。而受试者空腹血浆葡萄糖、游离脂肪酸水平与其下丘脑功能磁共振采集信号各项参数间没有关联。结论不同体重者下丘脑对糖负荷的中枢反应有所不同,肥胖者下丘脑对糖刺激反应的敏感性有所降低。功能核磁共振是确定脑特定区域功能的一个有效手段。
Objective To observe the response of hypothalamus to oral glucose tolerance test with functional nuclear magnetic resonance (NMR) and to reveal the relationship between the sensitivity of hypothalamic central glucose metabolism and metabolic disorders in different body weight. Methods Hypothalamus functional imaging data and abdominal anatomy image data of 10 normal and 10 obese subjects were collected respectively. The fasting blood glucose, free fatty acids and their corresponding hormone levels were also measured. The self-established gray mean method was used for image analysis and processing. At the same time, the correlation between brain function signal parameters and blood biochemical indexes, corresponding hormone levels and abdominal fat content were analyzed. Results Different weights of oral glucose in the hypothalamus after a transient inhibitory response. However, obese patients with this inhibitory response appeared significantly delayed than normal weight; inhibitory response was significantly lower than normal weight; inhibitory response recovery time was significantly later than normal weight. The subject’s fasting plasma insulin and its hormone levels correlated with the time it took for the hypothalamic inhibitory signal to return to baseline; the subject’s abdominal fat content was also correlated with the time it took for the hypothalamic inhibitory signal to return to baseline. However, there was no correlation between fasting plasma glucose, free fatty acid levels and parameters of the hypothalamic FMRI signal. Conclusions The hypothalamus of different weight has a different central response to sugar load. The hypothalamus of obese people is less sensitive to sugar stimulation. Functional MRI is an effective means of determining the function of a particular area of the brain.