Now, advancing this research effort, a team of scientists from Japan, led by Professor Akiyoshi Saitoh from the Tokyo University of Science, has looked at oxytocin, a hormone conventionally known for its role in the female reproductive system and in inducing the feelings of love and well-being. “Oxytocin was recently found to be involved in regulating learning and memory performance, but so far, no previous study deals with the effect of oxytocin on Aβ-induced cognitive impairment,” Prof Saitoh says. Realizing this, Prof Saitoh’s group set out to connect the dots. Their findings are published in Biochemical and Biophysical Research Communication.
Prof Saitoh and team first perfused slices of the mouse hippocampus with Aβ to confirm that Aβ causes the signaling abilities of neurons in the slices to decline or–in other words–impairs their synaptic plasticity. Upon additional perfusion with oxytocin, however, the signaling abilities increased, suggesting that oxytocin can reverse the impairment of synaptic plasticity that Aβ causes.
To find out how oxytocin achieves this, they conducted a further series of experiments. In a normal brain, oxytocin acts by binding with special structures in the membranes of brain cells, called oxytocin receptors. The scientists artificially “blocked” these receptors in the mouse hippocampus slices to see if oxytocin could reverse Aβ-induced impairment of synaptic plasticity without binding to these receptors. Expectedly, when the receptors were blocked, oxytocin could not reverse the effect of Aβ, which shows that these receptors are essential for oxytocin to act.
Oxytocin is known to facilitate certain cellular chemical activities that are important in strengthening neuronal signaling potential and formation of memories, such as influx of calcium ions. Previous studies have suspected that Aβ suppresses some of these chemical activities. When the scientists artificially blocked these chemical activities, they found that addition of oxytocin addition to the hippocampal slices did not reverse the damage to synaptic plasticity caused by Aβ. Additionally, they found that oxytocin itself does not have any effect on synaptic plasticity in the hippocampus, but it is somehow able to reverse the ill-effects of Aβ.
Prof Saitoh remarks, “This is the first study in the world that has shown that oxytocin can reverse Aβ-induced impairments in the mouse hippocampus.” This is only a first step and further research remains to be conducted in vivo in animal models and then humans before sufficient knowledge can be gathered to reposition oxytocin into a drug for Alzheimer’s. But, Prof Saitoh remains hopeful. He concludes, “At present, there are no sufficiently satisfactory drugs to treat dementia, and new therapies with novel mechanisms of action are desired. Our study puts forth the interesting possibility that oxytocin could be a novel therapeutic modality for the treatment of memory loss associated with cognitive disorders such as Alzheimer’s disease. We expect that our findings will open up a new pathway to the creation of new drugs for the treatment of dementia caused by Alzheimer’s disease.”
I wrote about oxcytocin previously . Check out What is the value of hugging to read further on it.