A research of two neuroscientists, Giovanni Marsicano from the University of Bordeaux in France and Xia Zhang from the University of Ottawa in Canada, showed that this consequential effect occurs due to a hitherto unknown mechanism of signalling between neurons and astrocytes, brain cells which as a result of the current research were proved to be responsible for memory functions.
After a number of experiments on mice, the researchers discovered that tetrahydrocannabinol (THC), the psychoactive substance present in marijuana, damages relations between neurons in the hippocampus, a region of the brain vital to memory formation.
The experiments were conducted using mice with genetically modified changes in the work of receptor units causing a reaction to marijuana – the so-called CB1 receptors (cannabinoid receptor type 1). The functioning of these receptors depends on the type of cell they are located on. So, the results of the experiments, in which the mice were submitted to a number of memory tests, showed that the effect of THC on the brain is associated with CB1 receptors in astrocytes, which means that the principal ingredient of marijuana degrades memory functions.
The researchers noted that the new findings could someday lead to the development of drugs with the same therapeutic characteristics but with fewer side effects.