Russian specialists found out how nanoparticles of viruses, organic and inorganic substances from the environment penetrate the brain.

The blood-brain barrier acts as a filter for such particles, so few substances can penetrate the brain. It also complicates drug delivery to the brain. But, as it turned out, there is another way of penetration. As part of the experiment, laboratory animals were instilled with a solution of nanoparticles in the nasal cavity and their appearance in the brain structures was monitored by MRI. In the olfactory bulb, particles appeared after 3 hours (max. concentration after 12 hours), in the hippocampus, dentate gyrus and other brain structures, the maximum was reached after 3-4 days. The movement of particles corresponded to the trajectory of the nerve connections of the olfactory system.

According to scientists, particles can pass through synapses, moving in nerve fibers. However, not all particles pass through the synapses. Manganese oxide passes through synapses, but silicon dioxide does not. The fact is that manganese oxide, unlike silicon dioxide, binds tightly to the AP-3 protein, which is involved in synaptic transmission processes. That is, in theory, nanoparticles can be delivered through the nasal cavity.

However, there are a number of reservations.

Experts have discovered combinations of chemical compounds that either completely block or significantly enhance the transport of nanoparticles from the nasal cavity to the brain. It was also noted that with the introduction of some nanoparticles, the rodent's body temperature quickly decreased and cerebrospinal fluid outflowed. That is, a large number of important reactions occur in the nasal cavity.