Histamine improves memory

Japanese researchers have shown that the delivery of this mediator in the brain improves the recovery of memories in mice, but also in humans.

By Paul Benkimoun Posted today at 14:34

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If pathological phenomena (neurodegenerative diseases) or molecules with an amnesia effect can erase our memories, the most common means is simply time. Memories engraved in the depths of our long-term memory – prompted to remember memories that are more than forty-eight hours old – are not the easiest to dig up. Proust suggests that it can be done with a madeleine, but it is more likely that this happens with histamine. This is the eventuality that the work of Japanese researchers tends to be published on Tuesday, January 8 by the magazine Biological psychiatry.

Histamine is involved in multiple effects in the body, including allergy. It is a mediator that acts on various organs or tissues by binding to histaminergic receptors. There are four types of receivers. In the 1980s, the French team of Jean-Charles Schwartz identified the H3 receptor, present in the neurons of the central nervous system.

Memory test in the Hiroshi Nomura laboratory at the University of Tokyo.
Memory test in the Hiroshi Nomura laboratory at the University of Tokyo. Hiroshi Nomura

These researchers "Immediately proposed and subsequently developed antagonists or inverse agonists H3 to activate the brain release of histaminereminds Michel Hamon, neuropharmacologist and vice-chairman of the Foundation for Brain Research. Since then, numerous clinical trials have sought to demonstrate the interest of blocking / inactivating H3 receptors to counter the cognitive deficits associated with various pathologies (schizophrenia, Alzheimer's, etc.). But no "therapeutic" application has really succeeded. "

Hiroshi Nomura and his colleagues at the University of Tokyo were interested in these H3 receptors, looking for non-invasive ways to promote the recovery of memories. They explain that they are the fact that, taken in the long run, "Treatments with antihistamines not only cause drowsiness but also learning and memory". Hence their working hypothesis: using a molecule that works with the same histamine receptor but with the reverse pharmacological effect (a "reverse agonist"), in this case preferring the release of histamine instead of curbing, it would be possible to learn and improve memory.

Japanese researchers note that, "In several pioneering studies, inverse agonists of H3 receptors have been shown to improve memory performance, but they have not been shown to promote the recovery of forgotten memories over the long term."