Maddock Richard J, Buonocore Michael H, Lavoie Shawn P, Copeland Linda E, Kile Shawn J, Richards Anne L, Ryan John M
Department of Psychiatry and Behavioral Sciences, University of California Davis, Sacramento, CA 95817, USA.
Psychiatry Res. 2006 Nov 22;148(1):47-54. doi: 10.1016/j.pscychresns.2006.02.004. Epub 2006 Oct 3.
Proton magnetic resonance spectroscopy ((1)H-MRS) studies showing increased lactate during neural activation support a broader role for lactate in brain energy metabolism than was traditionally recognized. Proton MRS measures of brain lactate responses have been used to study regional brain metabolism in clinical populations. This study examined whether variations in blood glucose influence the lactate response to visual stimulation in the visual cortex. Six subjects were scanned twice, receiving either saline or 21% glucose intravenously. Using (1)H-MRS at 1.5 Tesla with a long echo time (TE=288 ms), the lactate doublet was visible at 1.32 ppm in the visual cortex of all subjects. Lactate increased significantly from resting to visual stimulation. Hyperglycemia had no effect on this increase. The order of the slice-selective gradients for defining the spectroscopy voxel had a pronounced effect on the extent of contamination by signal originating outside the voxel. The results of this preliminary study demonstrate a method for observing a consistent activity-stimulated increase in brain lactate at 1.5 T and show that variations in blood glucose across the normal range have little effect on this response.
质子磁共振波谱（(1)H-MRS）研究表明，神经激活期间乳酸增加，这支持了乳酸在脑能量代谢中发挥比传统认知更为广泛的作用。质子MRS对脑乳酸反应的测量已被用于研究临床人群的局部脑代谢。本研究探讨了血糖变化是否会影响视觉皮层对视觉刺激的乳酸反应。6名受试者接受了两次扫描，分别静脉注射生理盐水或21%葡萄糖。在1.5特斯拉场强下采用长回波时间（TE=288毫秒）的(1)H-MRS，所有受试者视觉皮层中均可见1.32 ppm处的乳酸双峰。从静息状态到视觉刺激，乳酸显著增加。高血糖对此增加无影响。定义波谱体素的层面选择梯度顺序对体素外信号产生的污染程度有显著影响。这项初步研究的结果证明了一种在1.5 T场强下观察到脑乳酸一致的活动刺激增加的方法，并表明正常范围内的血糖变化对该反应影响很小。
