Protein-Restricted Diet Decreased Signs of Alzheimer’s Disease in Mice

English: Diagram of how microtubules desintegr...

English: Diagram of how microtubules desintegrate with Alzheimer’s disease Français : La protéine Tau dans un neurone sain et dans un neurone malade Español: Esquema que muestra cómo se desintegran los microtúbulos en la enfermedad de Alzheimer (Photo credit: Wikipedia)

Enzymes act on the APP (Amyloid precursor prot...

Enzymes act on the APP (Amyloid precursor protein) and cut it into fragments of protein, one of which is called beta-amyloid and its crucial in the formation of senile plaques in Alzheimer (Photo credit: Wikipedia)

A recent study using mice with many of the characteristics of Alzheimer’s Disease raised the possibility that periodic cycles of a protein-restricted diet supplemented with specific amino acids might lessen the symptoms of the disease. The mice, who showed signs of advance stage Alzheimer’s, were placed on the protein-restricted diet supplemented with  amino acids every other week for four months. The dieting mice were better able to run mazes than the non-dieting mice, an indication that their cognitive ability had improved.

Why did the researchers use a protein restricted diet? The answer to that has to do with one of protein’s functions. Protein intake that results from diet is a regulator of  the growth hormone IGF-1. This is the hormone that helps young children’s body grow; however, in later life high levels of it are associated with age-related diseases like Alzheimer’s. What the researchers did was use the diet to reduce the IGF-1 levels in the mice between 30-70 percent. This increased the level of another protein called IGFBP-1 by eight-fold. This protein blocks the effects of IGF-1 by binding to it.

The second issue the researchers needed to address was the effects of the diet itself. Very restricted diets are difficult to keep up and usually result in chronically low weight, which can also cause medical issues. By placing the mice on the diet every other week and giving them the amino acid supplements, the mice were not subject to the typical side effects of restricted diets.

The protein restricted diet did not affect the levels of beta amyloid in the mice’s brains. Beta amyloids are protein fragments that fall off of amyloid precursor proteins, which naturally occur in the body. Under normal circumstances, the beta amyloid fragments are eliminated; but in Alzheimer patients, the fragments remain and group together to form hard amyloid plaques that position themselves between nerve cells in the brain and interfere with nerve function.

The diet did decrease tau phosphorylation in the hippocampus.  Tau forms naturally as part of a structure called a microtubule. The microtubule carries nutrients from one part of the nerve cell to another. Phosphorylation is what turns the tau on/off. Abnormal phosphorylation causes tau to function incorrectly and the microtubules become unstable, collapse and nutrients aren’t transported. That’s when cognitive function degenerates. By stopping too much tau from being developed in the hippocampus of the brain, the researchers lessened the age-related impairment in cognitive function.

 

 

 

 

 

 

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~ by chasm63 on February 15, 2013.

One Response to “Protein-Restricted Diet Decreased Signs of Alzheimer’s Disease in Mice”

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