Study of trace elements in human brain samples

Abstract

Analyses of human brain tissues are becoming of interest in the medical field since trace elements may influence in the cognitive functions as they are involved in metabolic processes and redox reactions. Besides, essential elements are required in the brain for development and maintenance of the central nervous system, and to play an important role in neurode- generative disorders. The aim of this study was to investigate on trace elements in two regions (hi ppocampus and medium frontal cortex) of human brains from normal individuals, selected according to Clinical Dementia Rating score. This research was approved by the Ethic Committee and brain samples from 32 normal individuals (17 females and 15 males) aged 51-95 years were provided from the Brain Bank of the Brazilian Aging Study Group of Sao Paulo University, Medical School. The brain tissues were cut using a titanium knife, ground, freeze-dried and then analyzed by neutron activation analysis. Samples and element standards were irradiated at the IEA-Rl nuclear reactor under a thermal neutron flux for Br, Fe, K, Na, Rb, Se and Zn determinations. Student's t test (p = 0.05) was applied for comparison of results. Results indicated higher concentrations of Fe, Se and Zn in frontal cortexthan those found in hi ppocampus. No significant difference was found between the genders for frontal cortex tissues. However, the males presented higher Zn concentrations (69± 8 mgIkg) in hi ppocampus than those presented by females (62 ± 6 mg/ kg). Comparative study based on two different age groups of individuals indicated that the element concentrations of hi ppocampus region from group aged 51 to 75 years showed significant difference for Fe from those for the group of 76 to 95 years. Most of our results agreed with the literature ones. It is our intention to extend the study to Alzheimer disease human brains. Biological certified reference materials were also analyzed for quality of the analytical results.