Local voltage clamping and organotypic cultures of nervous tissue were used to study the actions of a series of agents whose activity is associated with the functioning of the GABAergic and NOergic systems on slow sodium channels. GABA was found not to affect Na V 1.8 channel activity, in contrast to substance RGPU-260, a composition of L-arginine and mefebut (β-phenyl-γ-aminobutyric acid methyl ester). Synthetic substance RGPU-260, like its component mefebut, was shown by our data to be able to reduce the functional activity of Na V 1.8 channels, giving its use potential as a peripherally acting analgesic drug. Sodium nitroprusside also decreased the functional activity of these channels, though this effect was seen only at relatively high concentrations, while its simultaneous use with RGPU-260 did not lead to any increase in the action on slow sodium channels. Analysis of the resulting data suggested that Na V 1.8 channels located in the asynaptic membranes of primary sensory neurons are not controlled by the GABAergic or NOergic systems of the brain.

The possible mechanisms of ligand–receptor binding of arginine-containing tetrapeptides with the NaV1.8 channels in the primary sensory neuron were investigated. Ac-RERR-NH2 tetrapeptide, acting outside the neuronal membrane, was found to decrease voltage sensitivity of the examined channels. In contrast, the Ac-REАR-NH2 tetrapeptide did not exhibit the same effect. Conformational analysis was used to investigate the mechanisms of ligand–receptor binding of a number of studied short peptides; it suggested that positively charged guanidine side chains of two arginine residues played a key role in peptide binding. Another amino-acid residue (glutamic acid) should be located between these two arginine residues. Our calculations demonstrated that the mechanism of ligand–receptor binding could not be implemented if the distance between the guanidine groups in short peptide molecules was less than a defined threshold value. The results allow one to conclude that the Ac-RERR-NH2 tetrapeptide and several other peptides capable of binding with the NaV1.8 channel by the same molecular mechanism have the potential to become novel peripheral analgesic drugs.

Исследованы возможные механизмы лиганд-рецепторного связывания аргининсодержащих тетрапептидов с каналами NaV1.8 первичного сенсорного нейрона. Установлено, что тетрапептид Ac-RERR-NH2, действующий с наружной стороны нейрональной мембраны, снижает потенциалочувствительность исследуемых каналов. В отличие от этого тетрапептид Ac-REАR-NH2 не обладает такой способностью. Применение конформационного анализа для объяснения механизма лиганд-рецепторного связывания ряда коротких пептидов, исследованных нами в настоящей работе, позволило предположить, что ключевую роль здесь играют положительно заряженные гуанидиновые группы боковых цепей двух аргинильных остатков. Между этими остатками должен находиться еще один аминокислотный остаток, в нашем случае - глутаминовая кислота. Расчеты показывают, что механизм лиганд-рецепторного связывания не может быть реализован, когда указанные гуанидиновые группы в молекулах коротких пептидов оказываются на расстоянии, меньшем определенного порогового значения. Полученные данные позволяют заключить, что тетрапептид Ac-RERR-NH2, равно как и ряд других пептидов, способных к связыванию с каналом NaV1.8 по тому же механизму, могут претендовать на роль лекарственных субстанций анальгетиков периферического механизма действия.

We report here a comparative (using chemical, electrical, and optical stimulation) study of the electrophysiological properties of cultured hippocampal neurons from transgenic animals expressing a mutant presenilin 1 protein. All three types of stimulation were found to elicit the following differences from the wild type: with overall more active electrophysiological behavior (especially at the beginning of stimulation), mutant cells differed from wild-type neurons by not maintaining consistent activity over time. However, only optogenetic stimulation increased the absolute number of action potentials and decreased their amplitude as compared with the corresponding values in wild-type neurons. The molecular-cellular mechanisms of this effect are suitable for further studies, both basic and applied (to identify regimes for controlling the electrical activity of neurons).

The aim of the study was to elucidate the molecular mechanisms of the interconnection of the GABA-ergic and nociceptive systems at the level of the peripheral division of the CNS. The data obtained indicate that GABA does not affect the activation gating device of the NaV1.8 channel of the primary sensory neuron responsible for coding pain signals.This agent in a wide range of concentrations also does not affect the growth of neurites of sensory neurons of embryonic nervous tissue. These results confirm our assumption, expressed earlier that the asynaptic membrane of the primary nociceptive neuron is not under the control of the GABA-ergic system.

Using the patch-clamp, organotypic culture of the nervous tissue, confocal and atomic force microscopy methods, the processes of intracellular signaling in the sensory neuron have been studied. The obtained data allow us to conclude that in these processes, which are triggered by low-power СО2-laser radiation, Src-kinase participates as a sequential unit: against the background of the action of PP2, a specific inhibitor of Src-kinase, irradiation does not change the voltage sensitivity of the Nav1.8 channels of the membrane of the nociceptive neuron and does not affect the growth of neurites. It can be concluded that the use of low-power infrared irradiation, which triggers the transducer function of Na, K-ATPase, should lead to both modulation of nociceptive signals and regulation of gene expression. The results obtained by us on intact nociceptive neurons will allow us to develop physiologically adequate and safe methods of arresting chronic pain

In this paper we gave a comparative study of the various physico-chemical properties of the hippocampal neurons in cell culture model of Alzheimer's Desease (Presenilin 1 mutations). It is shown that chemical, electrical and optical effects increase neuronal excitability differently for wild-type and KI (PS1-M146V neurons). In contrast to wild type KI neurons were more excitable, especially at the beginning of stimulation, but over time, this activity has been decreasing. At the same time, only in the case of optogenetic stimulation, exceeding the absolute values of their numbers has been registered, which made it possible to reduce their effect on the corresponding indices in wild type neurons. Molecular-cellular mechanisms of this phenomenon can serve as a material for further studies, both fundamental and practical (determination of the regimes of regulation of the electrical activity of neurons).

To date, optogenetics is one of the most popular methods in the world in neuroscience. There are new equipment and devices created to keep the progress of this method. This article describes a light pulse generator developed at the Laboratory of Molecular Neurodegeneration, designed for optogenetic experiments.

Optogenetic is a powerful method that allows to modulate cellular physiological properties. In our article, we demonstrate changes of electrical properties of cellular membranes on HEK-293T and hippocampal neurons transfected with channelrhodopsins and halorhodopsins induced by blue and orange light stimulation.