Scientists have learned how marijuana affects the brain

Investigations of the influence of marijuana on the brain led to an unexpected discovery: it turned out that brain service cells , whose function was considered only support and nutrition of neurons, can actively monitor the state of the neuronal contacts and influence the work of neural circuits.

Marijuana helped scientists revise the principles of cellular brain architecture. It turned out that the service cells of the nervous tissue necessary for feeding and supporting the neurons can actively interfere with the work of the interneuronal connections. These service cells are called astrocytes; before anyone had the slightest idea to suspect them of running neural circuits.

Researchers from the scientific centers of Canada, China, France, the United States and Spain have studied the effect of tetrahydrocannabinol, the "active substance" of marijuana, on short-term memory. It is known that smoking marijuana negatively affects this kind of memory, that's just how the drug does it? With the help of electrodes implanted in rat brain, scientists have established that tetrahydrocannabinol weakens synapses in the hippocampus, the brain department responsible for memory. This was quite expected result: it is known that the processes of learning and memorization are accompanied by the formation of new inter-neural connections in the brain.

Then the researchers decided to look at the action of marijuana at the molecular level - at the level of cellular receptors. On the surface of neurons, there are special receptors for tetrahydronnabinol, called CB1. The scientists obtained GM mice, in which the hippocampal neurons stopped synthesizing this receptor. In some animals, CB1 synthesis was disabled in neurons using dopamine as a neurotransmitter, in others in neurons using gammaaminobutyric acid. The authors of the work believed that without appropriate receptors, marijuana would cease to exert influence on the synapses, and the molecular mechanism of its action on memory could be considered uncovered. Mice with a mutant receptor gene had to remember the pathway to the labyrinth before and after taking tetrahydronnabinol. But even with the receptors turned off, the mice still forgot the path they had just learned.

This led scientists to the idea that the whole thing could be in the same CB1-receptors, only located on the membranes of astrocytes. When these receptors were turned off, marijuana also stopped loosening the synapses in the hippocampus and the animals stopped rushing through the labyrinth, as if they were there for the first time in their lives. As the researchers write in an article published in the journal Cell, the activation of marijuana receptors in astrocytes led to the loss of receptors for glutamic acid, another neurotransmitter, among interneuronic compounds. And this, in turn, led to a weakening of the synaptic connection.

Tetrahydrocannabinol has a similar effect on the memory of rats and humans, so that, with all the differences in the structure of the nervous system, in this case we are most likely talking about the same processes. But the main result here is not even finding out the mechanisms of the influence of marijuana on memory, but the discovery of new functions in astrocytes. Obviously, neuroglial cells can be not just a support service: they are able to take an active part in the management of neural circuits, although they do not conduct the nerve impulse themselves. However, the authors also talk about the possible practical application of the results obtained. It is known that marijuana is often used for medical purposes to relieve pain and stress, therefore, knowing exactly how it works, you can create no less effective but less ambiguous analogues.

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