Melatonin Helps Boosts Memory
In mice, melatonin and its metabolites were found to promote long-term memories and protect against cognitive decline, stated a new study conducted by Tokyo Medical and Dental University (TMDU) researchers in Japan.
Cognitive decline in mice manifests as poor memory, and when tested on the novel object recognition task, the mice behave as if both objects are new.
‘Melatonin and two of its metabolites help memories stick around in the brain and shield mice, and potentially people, from cognitive decline.’
The research team was curious about the role of melatonin's metabolites in boosting memory and cognitive decline.
"We know that melatonin is converted into N1-acetyl-N2-formyl-5-methoxykynuramine (AFMK) and N1-acetyl-5-methoxykynuramine (AMK) in the brain," explains Hattori, "and we suspected that they might promote cognition."
Study Details and Results
The mice were given doses of melatonin and the two metabolites 1 hour later. Then, researchers tested their memory the next day.
Memory improved after melatonin treatment, and N1-acetyl-5-methoxykynuramine (AMK) was the most effective.
The metabolites accumulated in the brain's hippocampal region, the key necessary for turning experiences into memories.
On the novel object recognition task, for young mice, exposure to an object three times a day was enough for it to be remembered the next day .
Whereas older mice behaved as if both objects were new and unfamiliar - a clear sign of cognitive decline.
After administering one dose of AMK 15 min after a single exposure to an object, the older mice could remember the objects up to 4 days later.
Blocking melatonin from being converted into AMK in the brain didn't enhance long-term memory formation.
"We have shown that melatonin's metabolite AMK can facilitate memory formation in all ages of mice," says Hattori.
"Its effect on older mice is particularly encouraging and we are hopeful that future studies will show similar effects in older people. If this happens, AMK therapy could eventually be used to reduce the severity of Mild Cognitive Impairment and its potential conversion to Alzheimer's disease."
Source: Medindia