MOSCOW, May 23. /TASS/ Using infrared (IR) irradiation, researchers have developed a method of stimulating neurons in deep tissue layers while examining the brain and treating various diseases of the nervous system without surgical intervention. The study’s results were published in the journal Nature Communications.
"Our method opens up a wide range of prospects for its applications in fundamental research and for further developments," the study’s leader and chief of the Laboratory of Molecular Technologies at the Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry of the Russian Academy of Sciences (IBC RAS) Vsevolod Belousov said. "Our results will facilitate the creation of new ways for therapeutic stimulation or, conversely, for suppressing various cells’ functions in the body."
Pinpoint accuracy in stimulating neurons without pharmaceuticals, or surgery might help treat such diseases as Parkinson, depression, and epilepsy. Attempts to selectively stimulate target neurons have been already performed before. In 2005, American scientists managed to create neurons sensitive to light by using genetic engineering methods. At that time, the researchers established the ‘optogenetics’ method when protein-receptors ultra-sensitive to light were implanted into neurons. Once light was shined onto the neurons, the receptors were activated.
Researchers from IBC RAS, Institute of Higher Nervous Activity and Neurophysiology RAS, and Moscow State University utililzed the thermogenetic approach and applied the transient receptor potential cation channel sensitive not to the light but to fluctuations in temperature. The thermoreceptors TRPA1 are responsible for the thermal vision of snakes who can "see" warm objects remotely.
In order to confirm that the changed neurons can "feel" the warmth and this has an impact on the behavior of animals, the scientists staged an experiment with zebrafish. The fish were divided into two subgroups: those supplied with the serpent thermoreceptors TRPA1, and those without. The researchers then raised the temperature of the fishes’ bodies with infrared irradiation. The zebrafish with thermoreceptors experienced a pseudo-touch feeling on the spot which was irradiated and tried to swim away. The fish without thermoreceptors did not react in any way to the irradiation.
"The IR-irradiation can penetrate deeper inside the tissue and, consequently, offer an opportunity to stimulate deeper layers of the brain. Moreover, thermogenetics has a great advantage when used with small test animals, for instance, with juvenile fish or flies (drosophilas) which are scared by blue light used in conventional optogenetic experiments to activate neurons. IR-irradiation is not visible for such subjects and hence one can exclude the side effects of bright light on the lab animals."