Sampling Method Affects HR-MAS NMR Spectra of Healthy Caprine Brain Biopsies

Abstract

The metabolic profiling of tissue biopsies using high-resolution–magic angle spinning (HR-MAS) 1H nuclear magnetic resonance (NMR) spectroscopy may be influenced by experimental factors such as the sampling method. Therefore, we compared the effects of two different sampling methods on the metabolome of brain tissue obtained from the brainstem and thalamus of healthy goats by 1H HR-MAS NMR spectroscopy—in vivo-harvested biopsy by a minimally invasive stereotactic approach compared with postmortem-harvested sample by dissection with a scalpel. Lactate and creatine were elevated, and choline-containing compounds were altered in the postmortem compared to the in vivo-harvested samples, demonstrating rapid changes most likely due to sample ischemia. In addition, in the brainstem samples acetate and inositols, and in the thalamus samples ƴ-aminobutyric acid, were relatively increased postmortem, demonstrating regional differences in tissue degradation. In conclusion, in vivo-harvested brain biopsies show different metabolic alterations compared to postmortem-harvested samples, reflecting less tissue degradation. Sampling method and brain region should be taken into account in the analysis of metabolic profiles. To be as close as possible to the actual situation in the living individual, it is desirable to use brain samples obtained by stereotactic biopsy whenever possible.

High‐resolution magic angle spinning NMR for intact biological specimen analysis: Initial discovery, recent developments, and future directions

“…8 To systematically evaluate brain postmortem metabolite changes in different regions, a goat model study compared HRMAS-measured metabolic differences between two sampling methods, in vivo-harvested biopsies versus postmortemharvested samples. 119 Results from this study showed visible regional metabolic differences, and varied tissue degradation rates for different metabolites in the different regions. An unanticipated finding, however, showed that the acetate resonance, normally unobservable in the true in vivo spectra, was relatively high in various spectra-even for the in vivo-harvested biopsy samples-when compared with n-acetylaspartate findings in the same spectra.…”

“…HRMAS NMR studies involving a variety of animal models of human diseases have been reported in recent publications. The utilized species have included rat, 35,42,55,90,94,[96][97][98][99][100][101][102][103] mouse, 29,48,50,[104][105][106][107][108][109][110][111][112][113][114][115][116] zebrafish, 34,117,118 sheep, 119,120 swine, 121,122 dog, 123 and chicken. 124 In addition to tumors, commonly the subject of HRMAS NMR publications, findings in disease models such as Alzheimer's disease, 105,113 heart transplantation, 99 obesity, 50 and stress, 101,102,110 have been reported.…”

“…For instance, from the very beginning of the discovery of HRMAS, investigators recognized that human brain samples collected at autopsy could not provide a true representation of neurometabolism during life 8 . To systematically evaluate brain postmortem metabolite changes in different regions, a goat model study compared HRMAS‐measured metabolic differences between two sampling methods, in vivo‐harvested biopsies versus postmortem‐harvested samples 119 . Results from this study showed visible regional metabolic differences, and varied tissue degradation rates for different metabolites in the different regions.…”

Flexibility of equine bioenergetics and muscle plasticity in response to different types of training: An integrative approach, questioning existing paradigms

“…Proline was significantly upregulated in both muscle groups (1.16 fold in M. pectoralis and 1.39 fold in M. vastus lateralis) and is known to be a biomarker for collagen content in muscles of dogs [206]. In view of the previous remarks concerning collagen metabolism in healthy Friesian horses, more research is needed with that respect.…”