Project Professor Atsuhiko Hattori of Rikkyo University's College of Sports and Wellness and his colleagues have discovered that one of the causes of memory decline in old age may be a decrease in the amount of N1-acetyl-5-methoxykynuramine (AMK) in the hippocampus.
In 2021, this research group discovered that AMK, a metabolite of melatonin secreted at night from the pineal gland in the brain, has a strong long-term memory inducing effect (consolidation effect from short-term memory to long-term memory). ing. Therefore, in this study, we conducted an analysis using aged mice, assuming that AMK levels are also involved in age-related memory decline.
First, we investigated the synthesis pathway of AMK and found that melatonin secreted from the pineal gland reaches the hippocampus via the blood and is converted to AMK in the hippocampus. Next, as a result of measuring and comparing the amount of AMK in the hippocampus of young and old mice, it was found that the amount of AMK in old mice was drastically reduced to less than 1/20 of that in young mice. In aged mice, gene expression of enzymes involved in AMK synthesis was significantly reduced. Therefore, it was suggested that AMK may be one of the causes of age-related memory decline.
In fact, they found that administering AMK to mice induces phosphorylation of proteins important for memory formation in the hippocampus, suggesting that AMK is involved in "memory consolidation" from short-term memory to long-term memory. is considered possible.
Furthermore, in a comprehensive analysis of genes expressed in the hippocampus of old and young mice, we found that a group of genes involved in long-term memory formation decreased significantly with age.
In countries that have entered super-aging societies, improving the age-related decline in memory is an important issue for improving the quality of life (QOL) of the elderly. The results of this research are expected to lead to the development of new AMK-based drugs to improve age-related memory decline and improve memory in mild cognitive impairment (MCI), which is considered a pre-dementia stage.
