Regional absolute quantification in neurochemical profile of the canine brain: Investigation by 1H nuclear magnetic resonance spectroscopy and tissue extraction [chapter]

D -C Woo, C -B Choi, S -H Lee, E -J Bang, S -S Kim, H -S Rhim, S -Y Kim, K -H Kim, B -Y Choe
2009 International Federation for Medical and Biological Engineering Proceedings  
INTRODUCTION In vitro magnetic resonance spectroscopy (MRS) method is able to analyze metabolism exactly rather than in vivo MRS because in vitro MRS used to employ more homogeneous NMR solution samples and higher magnetic field strength. Thus, the results of in vitro MRS could be used to support pathologic/physiologic analysis. Although the various brain diseases of canine models have been applied by proton MRS [1], the quantitative concentrations of canine brain metabolites have not been
more » ... have not been fully provided yet. Thus, the present study was designed to characterize the neuro-chemical profile in the various parts of canine brain using proton MRS, tissue extraction and the external simulated phantom concentration quantification, compared with those of human and rat which has already been reported. [2, 3] MATERIALS AND METHODS Phantoms as external references, which were made of ten important metabolites of brain were separately made: NAA, tCr, Lac, Cho, Glu, Gln, GABA, mIns, Ala and Tau. Five pure bred 8kg (60 months) adult beagles were injected with intravenous propofol (6 mg/kg) and anesthetized by 2% isoflurane. After sacrificed, a canine skull was sectioned on the midline, and cut around the occipital, frontal, temporal, thalamus, cerebellum cortices and spinal cord (C-spine part). All tissues were frozen in situ by soaking liquid nitrogen directly in order to prevent decomposition. After the metabolite powders of each tissue were prepared using methanol-chloroform-water (M/C) extraction method [4], 90% heavy water solutions were made for MRS sample in 5mm MRS tubes. MRS parameters were: Proton resonance frequency = 500.384MHz (Varian spectrometer), CPMG spin echo pulse, relaxation/saturation delay time = 0.5/1.5 sec, acquisition time = 1.892 sec, data points = 15146, spectral width = 8000 Hz, number of scan = 256. The concentrations of 10 metabolites were measured as each metabolite peak was subtracted from an original signal using AMARES method, Lorenzian fitting and apodization (3Hz) of jMRUI-TM for the post-process and external phantom simulated quantification method. (Fig. 1) Table 1 shows the comparison of concentrations of brain metabolites in human, rat and canine brain tissues (mean± SD, mM). Figure 2 shows the 2D correlation spectroscopy (2D-COSY) in the canine frontal cortex and the cross peaks of Lac, Glu/Gln, mIns were identified. RESULTS DISCUSSION AND CONCLUSIONS The concentrations of most metabolites in the cerebral cortex tended generally to be higher rather than other neuronal parts such as cerebellum, thalamus and spinal cord. Comparing with human's and rat's [2,3], the metabolic concentrations of a canine brain tissue were more close to rat's metabolic concentration than human's metabolic concentration. The present study demonstrated the absolute quantification of canine neuronal parts using in vitro high resolution MRS with tissue extraction as a method to accurately measure metabolite concentration. Therefore, the present findings provide metabolic information of various canine neuronal regions and can be applied in the other canine studies. ACKNOWLEDGEMENTS
doi:10.1007/978-3-642-03889-1_68 fatcat:2fddeq66dfhnfktrrkmsxgqah4