Fat and stupid
Fat in the abdomen leads to dementia in old age
Neuroscientists from Rush University, working under the guidance of Professor Kalipada Pahan, have found that a protein known for its function of regulating fat metabolism in the liver is expressed by hippocampal cells and regulates memory and learning processes.
The liver is the main metabolizer of fats in the body. Liver cells are characterized by high expression of the receptor for the peroxisome-alpha proliferation activator, known as PPARalpha. This protein is responsible for fat metabolism in the liver. To their surprise, the researchers found that the cells of the mouse hippocampus – the region of the brain responsible for memory and learning – also express a large number of these receptors.
Abnormal fat metabolism is known to be a risk factor for dementia. According to statistics, people with excessive fat deposition in the abdominal area in middle age in old age are 3.6 times more likely to suffer from memory disorders and dementia.
In order to understand the reasons for this, the authors created two mouse models using chimeric embryos. In animals of one model, PPARalpha was expressed only by liver cells and was absent in the brain, and in animals of the second model, this protein, on the contrary, was expressed only by hippocampal cells. Animal observation showed that the absence of PPARalpha in the brain was accompanied by poor memory and poor learning ability, while the absence of this receptor in the liver did not affect cognitive abilities in any way.
The researchers found that PPARalpha directly stimulates the transcription factor CREB (a protein that binds to a cAMP-dependent element), which regulates the activity of various proteins involved in memory mechanisms.
Diagram from an article in Cell Reports
According to the authors, people with fatty deposits from the abdominal area have a decrease in the expression of PPARalpha by liver cells. Apparently, over time, this receptor gradually disappears from all cells of the body, including hippocampal neurons. Thus, the presence of so-called abdominal fat is a kind of early prognostic factor for the development of a particular form of dementia in old age.
The authors hope that further research will help to find mechanisms for maintaining normal levels of PPARalpha expression in the hippocampus in order to prevent age-related memory and cognitive function disorders.
Article by Avik Roy et al. Regulation of Cyclic AMP Response Element Binding and Hippocampal Plasticity-Related Genes by Peroxisome Proliferator-Activated Receptor a is published in the journal Cell Reports.
Evgeniya Ryabtseva
Portal "Eternal youth" http://vechnayamolodost.ru based on the materials of Rush University Medical Center:
Neurological Researchers Find Fat May Be Linked to Memory Loss.
11.10.2013