A new magnetic resonance imaging (MRI) technique has allowed scientists to observe epigenetic changes in the brain.
This proof-of-concept study was able to detect changes in the expression of genes in the brains of piglets. The multidisciplinary team at the University of Illinois Urbana-Champaign, are now looking to use this technique, termed epigenetic MRI (eMRI), to gain insights into how the brain responds to certain environmental stimuli and disease.
Study co-leader, Professor Gene Robinson, told Technology Networks: 'There is an extensive literature from many laboratories, including some of ours, showing that there are changes in brain gene expression and epigenetic changes in the brain in response to a variety of experiences and exposures'.
It is thought that understanding changes in DNA methylation in the brain could help researchers to understand how the brain ages and neurological diseases including Alzheimer's disease and Huntington's disease progress.
Every cell carries the same DNA, but individual genes are turned on and off in each cell to allow it to carry out its function and respond to changes. In order for a gene to be 'turned on' it has to be transcribed, which requires the DNA to be unravelled so cell machinery can access the correct part of the genome. A type of epigenetic change called DNA methylation occurs when this happens and this can be used to determine which genes are active, and changes made by this process can last for hours, days or even longer.
Current methods to study epigenetic changes require either sampling of brain tissue or the creation of transgenic animals, however, eMRI could allow researchers to observe these changes in live brains. MRI is able to detect the presence of carbon-13, a molecule already approved for use in humans. The team used carbon-13-labeled methionine (an essential amino acid) to carry carbon-13 into the brain where it is used for DNA methylation.
Researchers fed some piglets a carbon-13 enriched diet for 10-32 days and controls the same diet but without carbon-13 enrichment, before euthanizing them and taking brain samples. Not only were researchers able to determine that DNA methylation varied in different regions of the brain and that a carbon-13 enriched diet could be used to image this in an MRI, but that there was more DNA methylation in the brain after a few weeks than there was at birth.
'This finding is very encouraging because it reflects what we expect to see if this signal is environmentally responsive,' said study co-leader Dr King Li. 'It is known from animal studies that brain regions that are most involved in learning and memory experience more epigenetic changes. There also were regional differences in DNA methylation across the pig brain, just like there are regional differences in classical MRI studies.'
The authors suggest that the use of eMRI could enable new investigations of the human brain and the changes occurring in neurodegenerative disease.
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