Biologičeskie membrany

A method for evaluation of metabolic characteristics of intact cells based on electrochemical registration of their respiratory activity was used to monitor a reaction of lymphocytes to a potential pharmacological agent, 2-(chlorodinitromethyl)-4-methoxy-6-(4-methylpiperazin-1-yl)-1,3,5-triazine. The method ensured an estimation of cytotoxicity of the test compound and made it possible to determine its minimum toxic concentrations for human lymphocytes. It was shown that the obtained results agree with the data of a reference method – MTT-based cell viability assay.

It is known that mTORC1-dependent pathway is involved in the activation of muscle protein synthesis and hypertrophy in response to mechanical stress. However, mechanosensors that mediate sensing and transmission of mechanical signals to the mTORC1 signaling pathway (mechanotransduction) are not yet identified. Mechanically activated (MA) ion channels are viewed as potential candidates for the role of such sarcolemmal mechanosensors. The aim of our work was to investigate the potential role of MA channels (Piezo1) in the activation of the mTORC1 pathway in the isolated rat soleus muscle in response to mechanical stress. Wistar rats were divided into 3 groups: 1) “Control” (isolated muscles were not exposed to MA channel inhibitor or Piezo1 channel activator); 2) “Gadolinium” (muscles were incubated with MA channel inhibitor, gadolinium chloride); 3) “Yoda” (muscles were incubated with Yoda1, Piezo1 activator). In rats from each group, the soleus from the left limb was incubated in the appropriate solution without mechanical stress in the form of a passive stretching, and the soleus from the right limb was subjected to passive stretching and then incubated in the appropriate solution. Phosphorylation of mTORC1 targets (p70S6K, rpS6, 4E-BP1) in rat soleus was determined by PAGE and immunoblotting. After passive stretching of the isolated soleus muscle there was an increase in phosphorylation of p70S6K, its substrate, rpS6, as well as 4E-BP1, by 38.5%, 168%, and 112%, respectively, compared to the soleus muscle that was not subjected to stretching. Incubation of the muscles with gadolinium completely prevented the activation of mTORC1 markers caused by stretching. Incubation of the soleus muscle in the solution with Yoda1 resulted in a decrease in the mechano-dependent phosphorylation of p70S6K, rpS6, and 4E-BP1 compared to a muscle that was not exposed to Yoda1. Thus, Piezo1 channels do not appear to play a role in the activation of mTORC1 signaling in rat soleus muscle in response to passive stretching.

In the aging and the development of age-associated diseases, the trigger mechanism is the hyperactivation of the hypothalamic-pituitary-adrenal neuroendocrine axis, hypersecretion of glucocorticoids, which, under excessive and long-term stimulation, have inflammatory and degenerative effects. Chronic stress exacerbates glucocorticoid-dependent atrophic changes in the aging brain, increases neuroinflammation and neurological dysfunction, and is a key risk factor for Alzheimer’s disease. In the correction of aseptic neuroinflammation in elderly and senile patients, the use of anti-inflammatory agents that exhibit anti-glucocorticoid (pro-anabolic) and anti-glutamate (anti-excitotoxic) effects is pathogenetically justified. Succinate/SUCNR1 signalling is involved in the development of immunomodulatory, trophic, and antihypoxic effects; however, its role in the mechanisms of the stress response remains unexplored. The aim of this study was to assay the impact of succinate/SUCNR1 signalling on the development of stress-induced neuroinflammation in the cerebral cortex of old rats. The work was performed on outbred albino male rats at the age of 18 months. Chronic restraint stress was modelled by immobilizing animals in individual plastic cases for 6 h daily for 5 days. Mexidol (2-ethyl-6-methyl-3-hydroxypyridine (EMHP) succinate) was used as a form of succinate that crosses the blood-brain barrier. Mexidol was administered intraperitoneally to old rats at a dose of 100 mg/kg daily for 5 days 15 min before the onset of stress. The levels of proinflammatory cytokines (IL-1β, TNF-α), anti-inflammatory cytokines (TGF-β1, IL-10), glucocorticoid receptors (GRα), transcriptional coactivator PGC-1α, succinate receptor SUCNR1/GPR91, and vascular endothelial growth factor (VEGF) were determined by immunoblotting in cerebral cortex (CC) samples. It was shown that chronic immobilization stress caused an increase in the level of IL-1β and TNF-α during stress, which was accompanied by a decrease in the content of anti-inflammatory cytokines, SUCNR1, GRα, PGC-1α. The course administration of EMHP succinate limited the development of stress-induced neuroinflammation in the CC of old rats and prevented a decrease in the levels of SUCNR1, IL-10, TGF-β1, PGC-1α, and GRα. The study reveals for the first time the stress-protective potential of succinate/SUCNR1 signalling in the brain of old rats associated with the activation of PGC-1α-dependent anti-inflammatory mechanisms under conditions of chronic stress.

It is known that activated derivatives of long-chain fatty acids acylcarnitines (LCAC) are considered the most toxic, which, along with calcium, can participate in the induction of mitochondrial permeability transition pore, involving various types of phospholipases in the complex mechanisms of pore activation. In this work, we investigated the influence of different inhibitors of phospholipases and carnitine palmitoyltransferase-1 (CPT1) on the induction of mitochondrial permeability transition pore by D,L-palmitylcarnitine (PC, C16:0). In the experiments on isolated rat liver mitochondria, the effects of PC on mitochondrial respiration rate, mitochondrial potential (ΔΨm), and mitochondrial swelling were examined. It was shown that the application of the inhibitors of carnitine palmitoyltransferase-1 (Etomoxir 2), Ca²⁺-dependent phospholipase cPLA2 (Aristolochic acid), or Ca²⁺-independent phospholipase iPLA2γ ((R/S)-bromoenol lactone (BEL) and PACOCF3) caused an increase in the critical concentrations of D,L-palmitylcarnitine (PC*) required for ΔΨm dissipation and mitochondrial swelling. The most pronounced protective effect was caused by PACOCF3 and BEL. In state 3 of respiration (ADP + Mg²⁺ + hexokinase), Etomoxir 2 and Aristolochic acid enhanced respiration inhibition induced by excess D,L-palmitylcarnitine and promoted dissipation of ΔΨm, while-the inhibitors of iPLA2γ prevented the dissipation of ΔΨm evoked by D,L-palmitylcarnitine and caused an increase in the rate of mitochondrial respiration. Thus, the results obtained indicate the involvement of mitochondrial iPLA2γ in the induction of mitochondrial permeability transition pore by long-chain acylcarnitines.

Neurodegeneration is a complex progressive pathological process leading to the neuronal death, which is induced by various external and internal factors. Neurodegenerative diseases, injuries of the central and peripheral nervous system, mental disorders, and a number of other pathological conditions, accompanied by functional and structural degradation of neurons and their death, is a serious problem in the global healthcare system, as due to these diseases millions of people around the world become disabled or die every year. The situation is complicated by the lack of selective, clinically effective neuroprotective drugs. It has been shown that nitric oxide (NO) and hydrogen sulfide (H₂S) are actively involved in neurodegeneration and cell death of neurons and glia, but their role is not completely clear. This review considers NO- and H₂S-dependent signaling mechanisms underlying the pathogenesis of neurodegenerative processes. The prospects for further studies of the role of NO and H₂S in the nervous tissue under conditions of pathological conditions associated with neurodegeneration are considered.