Center for Magnetic Resonance Research, Department of Radiology, University of Minnesota Medical School, Minneapolis, Minnesota 55455, USA.
Magn Reson Med. 2009 Dec;62(6):1385-93. doi: 10.1002/mrm.22146.
To quantitatively investigate the effects of pentobarbital anesthesia on brain activity, brain metabolite concentrations and cerebral metabolic rate of glucose, in vivo proton MR spectra, and electroencephalography were measured in the rat brain with various doses of pentobarbital. The results show that (1) the resonances attributed to propylene glycol, a solvent in pentobarbital injection solution, can be robustly detected and quantified in the brain; (2) the concentration of most brain metabolites remained constant under the isoelectric state (silent electroencephalography) with a high dose of pentobarbital compared to mild isoflurane anesthesia condition, except for a reduction of 61% in the brain glucose level, which was associated with a 37% decrease in cerebral metabolic rate of glucose, suggesting a significant amount of "housekeeping" energy for maintaining brain cellular integrity under the isoelectric state; and (3) electroencephalography and cerebral metabolic activities were tightly coupled to the pentobarbital anesthesia depth and they can be indirectly quantified by the propylene glycol resonance signal at 1.13 ppm. This study indicates that in vivo proton MR spectroscopy can be used to measure changes in cerebral metabolite concentrations and cerebral metabolic rate of glucose under varied pentobarbital anesthesia states; moreover, the propylene glycol signal provides a sensitive biomarker for quantitatively monitoring these changes and anesthesia depth noninvasively.
为了定量研究戊巴比妥麻醉对大脑活动、脑代谢物浓度和脑葡萄糖代谢率的影响，我们在大鼠脑内用不同剂量的戊巴比妥测量了体内质子磁共振波谱和脑电图。结果表明：(1) 戊巴比妥注射液溶剂丙二醇的共振可以在大脑中被稳健地检测和定量；(2) 与轻度异氟烷麻醉相比，高剂量戊巴比妥下大多数脑代谢物的浓度在等电状态（脑电图静默）下保持不变，除了脑葡萄糖水平降低 61%，这与脑葡萄糖代谢率降低 37%有关，表明在等电状态下，大量的“维持细胞完整性”能量用于维持大脑细胞的完整性；(3) 脑电图和脑代谢活动与戊巴比妥麻醉深度紧密相关，它们可以通过 1.13ppm 处的丙二醇共振信号间接定量。本研究表明，体内质子磁共振波谱可用于测量不同戊巴比妥麻醉状态下脑代谢物浓度和脑葡萄糖代谢率的变化；此外，丙二醇信号提供了一种敏感的生物标志物，可无创地定量监测这些变化和麻醉深度。
