A group at the University of Toyama revealed that atrophy of the skeletal muscle of Alzheimer's disease model mice secretes harmful molecules and accelerates the onset of dementia.
The relationship between lack of exercise and dementia is due to the high coexistence rate of sarcopenia, which is a condition in which muscle mass and strength are reduced due to aging, and dementia, and the fact that long-term hospitalization in old age increases the risk of developing dementia. It has also been pointed out.Therefore, we investigated the direct relationship between atrophy of skeletal muscle, which is an organ that plays a central role in exercise, and cognitive decline.
In the experiment, a model mouse with Alzheimer's disease was used, and the hind limbs were fixed with a cast for 2 weeks in a young mouse before the onset of memory impairment to cause skeletal muscle atrophy.Immediately after that, the memory ability was examined, and it was found that the muscularly atrophied mice developed memory impairment in spite of their young age.On the other hand, the memory ability was normal in the non-casting and muscular atrophied mice.
Next, when we examined the substances secreted by the atrophied skeletal muscle of mice, we found that the amount of hemopexin was increased.Since hemopexin was increased not only in skeletal muscle but also in the blood and hippocampus of the brain, it is considered that hemopexin secreted from skeletal muscle reaches the brain via blood.
Furthermore, it was found that continuous administration of hemopexin into the brain of a very young Alzheimer's disease model mouse before the onset of cognitive impairment for 2 weeks increased factors involved in neuroinflammation and developed memory impairment.From the above, the mechanism by which hemopexin secreted when skeletal muscle atrophy is transferred to the brain and accelerates the onset of dementia via neuroinflammation has been clarified.
Since it became clear that skeletal muscle atrophy alone triggers cognitive dysfunction, it is expected that this finding will be applied to efforts aimed at preventing the onset of dementia by targeting skeletal muscle and hemopexin. Will be done.
Paper information:[Journal of Cachexia, Sarcopenia and Muscle] Skeletal muscle atrophy-induced hemopexin accelerates onset of cognitive impairment in Alzheimer's disease
