Memory impairment in mice reduced by soy derivate that can enter the
brain intact

Date:
June 19, 2020
Source:
Kyushu University
Summary:
Researchers have found that a soy-derived protein fragment that
reaches the brain after being ingested reduces memory degradation
in mice with an induced cognitive impairment, providing a new
lead for the development of functional foods that help prevent
mental decline.



FULL STORY ==========================================================================
In a study that could help one day give a literal meaning to food for
thought, researchers from Kyushu University in Japan have reported that a protein fragment that makes its way into the brain after being ingested
can reduce memory degradation in mice treated to simulate Alzheimer's
disease.


========================================================================== Derived by breaking apart the proteins in soybeans, the memory-effecting molecule is classified as a dipeptide because it contains just two
of the protein building blocks known as amino acids. Unique about the
dipeptide used in the study is that it is currently the only one known
to make the trip from a mouse's stomach to its brain intact despite the
odds against it.

"On top of the possibility of being broken down during digestion, peptides
then face the challenge of crossing a highly selectively barrier to
get from the blood into the brain," says Toshiro Matsui, professor in
the Faculty of Agriculture at Kyushu University and leader of the study published in npj Science of Food.

"While our previous studies were the first to identify a dipeptide able
to make the journey, our new studies now show that it can actually affect memory in mice." Working in collaboration with researchers at Fukuoka University, the researchers investigated the effects of the dipeptide --
named Tyr-Pro because it consists of the amino acids tyrosine and proline
-- by feeding it to mice for several days before and after injecting them
with a chemical that is commonly used to simulate Alzheimer's disease
by impairing memory functions.

In tests to evaluate short-term memory by comparing a mouse's tendency to explore different arms of a simple maze, impaired mice that had ingested
the dipeptide over the past two weeks fared better than those that
had not, though both groups were overall outperformed by mice without
induced memory impairment. The same trend was also found in long-term
memory tests measuring how long a mouse stays in the lighted area of an enclosure to avoid a mild electrical shock experienced in the dark area
after having been trained in the box a day before.

Though there have been other reports suggesting some peptides can reduce
the decline of brain functions, this is the first case where evidence
also exists that the peptide can enter the brain intact.

"We still need studies to see if these benefits carry over to humans,
but we hope that this is a step toward functional foods that could help
prevent memory degradation or even improve our memories," comments Matsui.


========================================================================== Story Source: Materials provided by Kyushu_University. Note: Content
may be edited for style and length.


========================================================================== Journal Reference:
1. Mitsuru Tanaka, Hayato Kiyohara, Atsuko Yoshino, Akihiro Nakano,
Fuyuko
Takata, Shinya Dohgu, Yasufumi Kataoka, Toshiro Matsui. Brain-
transportable soy dipeptide, Tyr-Pro, attenuates amyloid b
peptide25-35- induced memory impairment in mice. npj Science of
Food, 2020; 4 (1) DOI: 10.1038/s41538-020-0067-3 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/06/200619104312.htm

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