French researchers have discovered that cannabis acts on the mitochondria located in the region of the hippocampus, causing memory loss.
“My memory is failing, I don’t remember very well”. Jeanne Moreau’s famous words are not unknown to regular cannabis smokers. They are indeed often victims of short or long term memory loss. This side effect of cannabis exposure is widely described in the scientific literature, but the origin of these disorders has not been fully identified.
In a study published in Nature, French researchers from Inserm present an explanation.
The research team began with the observation that these memory losses were linked to receptors on the surface of several types of nerve cells in the brain. In-depth analyzes have shown that these receptors that cannabis binds to are also present on the surface of the mitochondria.
These small structures located inside cells are responsible for producing energy. The brain, which consumes more than 25% of this generated energy, cannot function without them. Mitochondrial diseases also demonstrate their essential role: when they are affected, patients suffer from neuropsychological and neurological disorders.
The hippocampus targeted by cannabis
However, the involvement of these mini-power plants in learning and memory mechanisms had not yet been clearly shown. To do this, scientists exposed mice to cannabis and observed them. They then noted that the active molecule of this drug, delta9-tetrahydrocannabinol or THC, causes amnesia in these guinea pigs, by attaching to the mitochondria of neurons present in the region of the hippocampus, the seat of memory.
On the other hand, when researchers genetically modify mice so that they no longer express these receptors on the surface of their cells and mitochondria, cannabis has no memory effects. “We therefore believe that the mitochondria develop our memory by providing energy to the brain cells,” says Giovanni Marsicano, responsible for this work.
For the researchers, this study not only provides information on the impact of cannabis on memory, but also reveals that mitochondrial activity is an integral part of brain functions.
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