X-ray fluorescence analysis of long-term changes in the levels and distributions of trace elements in the rat brain following mechanical injury

Abstract

This paper describes the results of the application of X-ray fluorescence microscopy to the qualitative, topographic and quantitative elemental analysis of nervous tissue from rats with neocortical brain injury. The tissue samples were analyzed with a 15 μm beam defined by the size of the polycapillary focus. Raster scanning of the samples generated 2D cartographies, revealing the distributions of elements such as P, S, Cl, K, Ca, Fe, Cu, and Zn. Special emphasis was placed on the analysis of the areas neighboring the lesion site and the hippocampal formation tissue. The results obtained for rats with mechanical brain injuries were compared with those recorded for controls and animals with pilocarpine-induced seizures. There were no significant differences in the elemental compositions of gray and white matter between injured and uninjured brain hemispheres. A higher level of Ca was observed in the gray matter of both of the hemispheres in brains with neocortical injuries. A similar relation was noticed for Fe in the white matter. A comparative study of hippocampal formation tissue showed a statistically significant decrease in the mass per unit area of P in the dentate gyrus (DG) and the hilus (H) of DG for animals with brain lesions in comparison with the control group. Analogous relations were found for Cu in the DG and Zn in sector 3 of Ammon’s horn (CA3) and the DG. It is important to note that identical changes in the same areas were observed for animals with pilocarpine-induced seizures in our previous study.

Laminar-specific distribution of zinc: Evidence for presence of layer IV in forelimb motor cortex in the rat

“…Our study has demonstrated that normalizing the average Zn concentration in each cortical layer to that of the corpus callosum in the same brain section reduces inter- and intra-animal variability between tissue sections (see Supplementary information). Most importantly, the Zn concentration determined for each tissue layer of the cortex in this study is consistent with some previous studies (Chwiej et al, 2011; Frederickson et al, 2000; Hare et al, 2010; Lee et al, 2011; Wang et al, 2010) and falls within the normal physiological range. Likewise, the ratio of bulk Zn concentration in the cortex and corpus callosum is also in general agreement with previous findings (Chwiej et al, 2011; Sergeant et al, 2005).…”

“…Therefore, it was hypothesized that the existence of layer IV would be portrayed by a region of decreased Zn concentration situated between layers III and V in both motor and sensory-motor cortices. This study employed X-ray fluorescence imaging at the micron level (XFI) using a synchrotron generated X-ray source, a technique previously utilized to study tissue architecture on the basis of elemental composition (e.g., Chwiej et al, 2011; James et al, 2011; Leskovjan et al, 2009; Linkous et al, 2008; Miller et al, 2006; Popescu et al, 2009a, 2009b). Since rat model systems are among the most widely used to study neurological and neurodegenerative disorders affecting hand function, clarification of this question is critical to both mechanistic understanding and therapeutic development.…”

Variations in elemental compositions of rat hippocampal formation between acute and latent phases of pilocarpine-induced epilepsy: an X-ray fluorescence microscopy study

“…This article is a continuation of our previous studies which analyzed changes in the accumulation of metals resulting from seizures, mechanical brain injury, and the use of the neuroprotective agent FK-506 [5][6][7]. We try to verify whether the compositional changes of Ca, Cu, and Zn [5], observed before for the acute period of pilocarpineinduced status epilepticus, were temporary or permanent irreversible effects.…”

The influence of the ketogenic diet on the elemental and biochemical compositions of the hippocampal formation

“…For the analysis of distribution and accumulation of selected elements within the hippocampal formation, X-ray fluorescence microscopy (XRFM) was used, while biochemical evaluation of particular hippocampal areas was done by applying synchrotron Fourier transform infrared microspectroscopy (FTIRM). Both techniques have been successfully applied in our previous studies concerning the mechanisms leading to epilepsy which were carried out mostly on the pilocarpine model of seizures [22][23][24][25][26][27][28][29]. Examining seizure-induced elemental changes of the hippocampal formation, we were able to follow the processes of excitotoxicity and mossy fiber sprouting occurring in this brain area [18][19][20].…”