Memory-enhancing compound: Melatonin takes the spotlight
In a groundbreaking study, researchers at Tokyo Medical and Dental University in Japan have discovered that melatonin and its metabolites can help memories persist in the brain. This finding could pave the way for new interventions for cognitive disorders in humans.
The study involved a common memory test in mice, which revealed that melatonin and its metabolites, specifically N1-acetyl-N2-formyl-5-methoxykynuramine (AFMK) and N1-acetyl-5-methoxykynuramine (AMK), can shield mice from cognitive decline.
After receiving a single dose of AMK, older mice were able to remember objects up to 4 days later, suggesting that melatonin and its metabolites can promote the formation of long-term memories and protect against cognitive decline in mice.
The team expects this finding could also translate to people. Melatonin, a supplement often used for sleep, has been found to potentially aid in memory retention and protection against cognitive decline.
Melatonin receptor modulation plays a crucial role in this process. Increased expression of the MT2 receptor in the hippocampus, a region associated with memory formation, correlates with improved memory performance and reduced inflammation.
Melatonin's anti-inflammatory action is another key factor. It suppresses proinflammatory cytokines and enhances anti-inflammatory cytokines, promoting a neuroprotective environment.
Moreover, melatonin accumulates in mitochondria, stabilizing electron transport chain components, reducing oxidative stress, and scavenging harmful radicals that can damage neurons. This mitochondrial protection is essential for maintaining brain health.
Melatonin signaling also influences clock genes and immune cell function, supporting circadian regulation and rejuvenation of exhausted immune cells. This neuroimmune regulation contributes to brain health.
By modulating neurotransmitter levels and receptor balance, melatonin facilitates synaptic changes underlying learning and memory processes. This enhanced synaptic plasticity is crucial for memory formation and cognitive abilities.
However, it's important to note that while melatonin shows promise, direct evidence of melatonin or its metabolites improving human memory or cognitive decline is still limited and requires rigorous clinical trials. The recommended starting dose for melatonin is one to two milligrams before bed, which can be gradually increased up to five milligrams if needed.
In summary, melatonin enhances memory and counters cognitive decline in mice via receptor-mediated anti-inflammatory, antioxidative, and neuroimmune mechanisms primarily in the hippocampus. These findings provide a promising basis for exploring melatonin-based interventions for human cognitive disorders, but more clinical research is needed to confirm efficacy and dosing.
