Russian scientists together with foreign colleagues have created new technologies that allow studying the metabolism of nerve cells in real time directly in the brain of animals. They tested their developments on a model of ischemic stroke in rats: fluorescent biosensors, whose genes were delivered to brain cells using viruses, reacted sensitively to changes in pH and the content of reactive oxygen species inside neurons. The new method will allow us to obtain data on the work of brain cells in normal and pathological conditions in their natural environment.
Ischemic stroke is one of the main causes of death and disability in the modern world. The disease occurs when the vessels of the brain are blocked, the cause of which may be vascular pathologies, changes in the properties and composition of blood, separation of blood clots, injuries. As a result, a part of the brain does not receive enough oxygen, ischemia develops and, if action is not taken quickly, the cells die.
"Despite the impressive amount of experimental data obtained over the past decades, biologists and physicians still lack information about the molecular mechanisms of stroke pathogenesis to create effective therapy. For example, it is commonly believed that oxidative stress in cells, that is, increased production of reactive oxygen species (ROS), is the main damaging factor in the acute phase of stroke, but scientists regularly suggest new mechanisms of cell damage.
At the same time, and, in our opinion, this is the key point, until recently it was not possible to directly show the dynamics of oxidative stress itself in the brain tissues of an experimental animal that develops an ischemic stroke. This applies not only to ROS, but also to other biochemical parameters. The technologies developed by us allow us to monitor intracellular changes in the brain of laboratory animals, starting from the first seconds of pathogenesis," says Dmitry Bilan, PhD, head of the group of metabolic bases of pathology of the IBH RAS.
Employees of the M. M. Shemyakin and Y. A. Ovchinnikov Institute of Bioorganic Chemistry of the Russian Academy of Sciences (Moscow), the Federal Center for Brain and Neurotechnology of the FMBA of Russia (Moscow), Lomonosov Moscow State University (Moscow) together with colleagues from other Russian and foreign institutes have developed a technology that allows you to track the dynamics of biochemical processes directly in the body.
With the help of viruses, scientists have embedded biosensor genes that they created earlier into rat brain cells. By their nature, they are protein molecules with fluorescent properties that react to changes in the acidity of the medium (pH) and fluctuations in the concentration of hydrogen peroxide — one of the main ROS in cells.
The authors artificially induced a stroke in animals by blocking an artery in the brain and observed a change in the glow of biosensors in neurons using optical fibers previously implanted in the brain. It turned out that already in the first seconds of the development of ischemia, the intracellular pH of neurons located at the epicenter of a stroke sharply decreases. A significant increase in the concentration of hydrogen peroxide was registered only the day after the operation. This result was unexpected for the researchers, since it was previously believed that significant generation of ROS occurs in the acute stage of stroke.
"Our work has united the efforts of scientists from different disciplines. To study the dynamics of pathological processes in the development of stroke, approaches of molecular biology and biochemistry, experimental surgery were used, new technical solutions for recording processes in living brain tissues were developed. In the future, the methodological base that we have developed can be used for any other studies of brain metabolism in normal and pathological disorders," Dmitry Bilan sums up.
The results of the work supported by a grant from the Russian Science Foundation (RNF) are published on the pages of the journal Redox Biology
PHOTO: Neuron with dendrites © Journal of Cell Biology/Flickr

Certificate of registration of mass media ЭЛ № ФС 77 - 78868 issued by Roskomnadzor on 07.08.2020