The Study of the Effectiveness of Ethylmethylhydroxypyridine Succinate in Acute Alcohol Intoxication.

The effectiveness of ethylmethylhydroxypyridine succinate (EMHPS) in acute alcohol intoxication was tested in a study on SPF male outbred ICR mice. Ethanol (concentration 40%) was administered to animals once intraperitoneally at a dose of 4 g/kg. Control animals were injected with saline in an equivalent volume. In 15 min after the administration of alcohol, the animals were injected intravenously or intramuscularly with EMHPS at a dose of 50 or 100 mg/kg or with saline via the same route in an equivalent volume. Animal behavior was tested 3 and 24 h later after administration of the substances. After 3 and 24 h, mice in the pathological control groups developed semiptosis, the gait and the turning over reflex were impaired, the strength of the hind limbs decreased and the distance between the hind limbs increased when landing; in the open-field test, the latency of the first movement increased, and the number of rearing postures decreased. Intravenous and intramuscular administration of EMHPS in doses of 50 and 100 mg/kg had a pronounced antitoxic and neuroprotective effect in acute alcohol intoxication: all studied parameters did not differ significantly from the control.

The effect of lactoferin on the free radical and cytokine status of cornea in the experimental thermal burn.

The free radical and cytokine statuses of the cornea during its thermal burn and the possibility of its correction by lactoferrin have been studied in Soviet Chinchilla rabbits. The development of a corneal thermal burn was accompanied by the development of oxidative stress (increased levels of TBA-reactive substances and carbonyl derivatives of proteins, decreased activity of SOD and GPx enzymes) and a pronounced inflammatory reaction with increased levels of TNF-1α, IL-10, TGF-1ß. The use of lactoferrin had a pronounced therapeutic effect, which was manifested by accelerated healing, prevention of the development of complications (corneal perforations), a decrease in the severity of oxidative stress, an increase in the concentrations of TNF-1α (in the early stages), IL-10 (in the later stages), TGF-1ß (throughout the experiment). At the same time, by the end of regeneration more severe corneal opacification was recognized compared to the control group. This may be associated with an increased level of anti-inflammatory cytokines, especially TGF-1ß.

[The Mechanism of Bimodal Effect of DL-Butyonine Sulfoximine on Constitutive Androstane and Pregnane X Receptors In Vitro].

The constitutive androstane receptor (CAR) and the pregnane X receptor (PXR) are nuclear receptors that are involved in the regulation of gene transcription of enzymes that are responsible for biotransformation and excretion of endo- and xenobiotics. The goal of the work was to study the effect of DL-butyonine sulfoximine (BSO, gamma-glutamylcysteine synthetase inhibitor) on the relative amounts of CAR and PXR in Caco-2 cells and to clarify its mechanisms. BSO was used at concentrations of 1-500 µM for 24 and 72 h. The generation of reactive oxygen species (ROS) has been evaluated using the MitoTracker Red CM-H2 XRos fluorescent probes. Cytotoxicity was analyzed by the MTT test. The relative amount of CAR and PXR was assessed by the Western blot method. It has been shown that BSO caused an increase in ROS formation at concentrations of 10, 50, and 100 µM for 24 h and at concentrations of 50 and 100 µM for 72 h. However, 500 µM BSO reduced the viability of cells during all periods of exposure. The relative amount of CAR increased in 24 h at the BSO concentrations of 50 and 100 µM and in 72 h at its concentrations of 10 and 50 µM. The amount of PXR increased in 72 h during incubation with BSO at the concentration of 50 µM and in 24 and 72 h at its concentrations of 100 and 500 µM. The combined use of BSO (50 µM, 24 h; 10 and 50 µM, 72 h) and glutathione inhibited CAR induction, whereas 50 and 100 µM BSO inhibited PXR formation for 72 h. The addition of 1 mM glutathione to the nutrient medium with BSO (100 and 500 µM, 24 h; 500 µM, 72 h) did not affect the relative amount of PXR. No effect on CAR was observed when 1 mM glutathione was used together with BSO (100 µM, 24 h; 50 and 100 µM, 72 h). Thus, BSO can induce CAR and PXR formation by both increasing the production of free radicals, thus developing oxidative stress, and by acting independently as a xenobiotic.

Pharmacokinetics of Succinate in Rats after Intravenous Administration of Mexidol.

The pharmacokinetics of succinate was studied in Wistar rats after a single intravenous administration of Mexidol in a dose 100 mg/kg body weight. The concentration of succinate in blood plasma, cytoplasmic and mitochondrial fractions of cells of the cerebral cortex, left-ventricular myocardium, and liver was measured by HPLC-MS/MS. After single intravenous administration of Mexidol, succinate was evenly distributed in organs and tissues and quickly eliminated from the body. The pharmacokinetics of succinate was described by a two-chamber model. An increase in the level of succinate in the cytoplasmic fraction of the liver, myocardium, and cerebral cortex cells and a minor increase in the mitochondrial fraction were observed. The maximum increase in the level of succinate in the cytoplasmic fraction was observed in the liver tissue, a less pronounced elevation was observed in the cerebral cortex and myocardium; no significant differences between the cerebral cortex and myocardium were observed by this parameter.

[Quantitative assessment of breast cancer resistance protein during pregnancy in rabbits]. / Kolichestvennaia otsenka belka rezistentnosti raka molochnoi zhelezy pri beremennosti u krolikov.

Breast cancer resistance protein (BCRP,ABCG2) is an efflux transporter protein that transports various substrates from the cell to the extracellular space or organ cavities. The aim of this study was a complex assessment of the amount of BCRP during pregnancy in rabbits. The amount of BCRP in samples of the rabbit jejunum, liver, kidney, cerebral cortex, and placenta was determined by enzyme immunoassay, and in human hepatocellular carcinoma (HepG2) cells by the Western blot. To study the mechanisms involved in control of the dynamic BCRP levels during pregnancy, serum concentrations of sex hormones were investigated by radioimmunoassay and relative amounts of constitutive androstane receptor (CAR) and pregnane X receptor (PXR) in these organs were evaluated using the Western blot method. The putative role of CAR and PXR in regulation of the BCRP level by progesterone was evaluated in vitro experiments on HepG2 cells. It was found that amount of BCRP in the jejunum of pregnant rabbits was higher than in the placenta, liver, kidneys, and cerebral cortex. An increase in the amount of BCRP in the liver of rabbits was noted on the 21st day of pregnancy and a tendency to the increase was also detected on the 28th day; in the kidney and cerebral cortex increased BCRP levels were detected on the 28th day and 14th day of pregnancy, respectively, as compared with non-pregnant females. In vitro experiments with HepG2 cells have shown that the increase in the BCRP level is determined by the activating effect of progesterone on PXR.

Functioning of P-Glycoprotein during Pregnancy in Rabbits.

The level P-glycoprotein (Pgp) in organs of pregnant rabbits and its content and activity in the placental barrier at different stages of pregnancy were studied. An increase in Pgp content in the jejunum on days 7, 14, 21, and 28 of pregnancy in comparison with this parameter non-pregnant females was revealed by ELISA; in the liver, Pgp content was higher on day 7 and tended to increase on day 14; in the kidney and cerebral cortex, Pgp content was higher on day 28 of pregnancy in parallel with an increase in serum progesterone concentration. We also observed a decrease in Pgp content in the placenta on days 21 and 28 of pregnancy in comparison with day 14 and a decrease in Pgp activity in the placental barrier, which was confirmed by enhanced penetration of fexofenadine (Pgp substrate) through the barrier.

The Effect of Original Russian Neurotropic Drugs on Organic Anion Transporting Polypeptides OATP1B1 and OATP1B3.

In experiments on HepG2 cells, we studied the effect of the original domestic neurotropic drugs omberacetam, fabomotizole, and ethylmethylhydroxypyridine succinate (EMHPS) (1-500 µM) on the activity and content of organic anion transporting polypeptides OATP1B1 and OATP1B3. It was shown that omberacetam (500 µM) increased the content of OATP1B1 and OATP1B3, fabomotizole did not affect the level of both transporters, and EMHPS (500 µM) increased the content of OATP1B1 compared to the control and did not affect the level of OATP1B3. The tested substances also reduced the OATP1B1/OATP1B3 ratio, as evidenced by a decrease in the penetration of atorvastatin, a substrate of the transporters, into HepG2 cells in the presence of omberacetam (100-500 µM), fabomotizole (500 µM), and EMHPS (10-500 µM). Evaluation of clinical significance of the obtained results, according to the FDA approach based on the calculation of the Cmax/IC50 ratio, showed that the effect of the tested substances on OATP1B1/OATP1B3 is clinically insignificant.

Mechanisms of P-Glycoprotein Regulation Under Exogenous and Endogenous Oxidative Stress In Vitro.

We investigated the mechanisms of P-glycoprotein (P-gp) transporter regulation in Caco-2 cells under exogenous and endogenous oxidative stress (OS). Exogenous OS was modeled by exposure of the growth medium to hydrogen peroxide at concentrations of 0.1, 0.5, and 1 µM for 24 h or 10 µM for 72 h. Endogenous OS was modeled by incubating cells with DL-buthionine sulfoximine (BSO, gamma-glutamylcysteine synthetase inhibitor) at a concentration of 10, 50, and 100 µM for 24 h. The levels of intracellular reactive oxygen species (ROS) were assessed using MitoTracker Red CM-H2XRos fluorescent probes. Relative P-gp contents were analyzed using Western blot. Exogenous and endogenous OS was shown to increase relative to P-gp contents. An important role played by the Nrf2-Keap1 signaling pathway in increasing the P-gp contents under H2O2-induced exogenous OS was revealed using specific inhibitors. The transcription factor HIF1 is involved in the regulation of the P-gp levels under 24-hour exogenous OS, and the transcription factor CAR is involved in the regulation of transporter levels under 72-hour OS. All tested transcription factors and signaling pathways are involved in P-gp induction under endogenous OS. Most likely, this is associated with the bimodal effect of BSO on Pgp. On the one hand, BSO induces the development of OS; on the other, BSO, as a xenobiotic, is able to stimulate PXR and CAR, which, in turn, increase the P-gp contents.

Development and validation of a methodology for quantitative determination of malondialdehyde by HPLC-MC/MS.

A bioanalytical technique for quantitative determination of MDA by HPLC-MS/MS. The proposed method for determining MDA includes the release stage of bound MDA and excludes the derivatization reaction. The lower limit of quantitative detection was 600 nmol/l, the volume of the required sample was 10 µl, the analysis time was 7 min. The range of concentrations obtained during the study makes it possible to use this bioanalytical technique to determine the concentration of MDA in biological material when assessing physiological and pathological conditions.

[Mechanism of regulation of the constitutive androstane receptor under conditions of modeling oxidative stress in vitro]. / Reguliatsiia konstitutivnogo androstanovogo retseptora v kletkakh linii Caso-2 pri modelirovanii okislitel'nogo stressa in vitro.

The constitutive androstane receptor (CAR) is a nuclear receptor that participates in the regulation of biotransformation of toxic substances and metabolic processes. The mechanisms of expression changes of CAR under conditions of oxidative stress (OS) have not been studied yet and this was the purpose of the study. OS was modeled by incubating Caco2 cells with hydrogen peroxide 10-100 µM for 72 h. The amount of CAR was determined by the Western blot, nuclear factor erythroid 2-related factor 2 (Nrf2) was evaluated by a heterogeneous enzyme immunoassay malondialdehyde (MDA), the lipid peroxidation products (LPP) was assayed by a photometric method. Incubation of cells with 10 µM and 50 µM H2O2 led to an increase in the amount of CAR and Nrf2, while incubation with 100 µM H2O2 caused their decrease. Nrf2 inhibition did not influence the CAR content under OS conditions. 10 µM MDA increased the CAR content, 100 µM MDA had no effect, while 150 µM reduced the amount of CAR.

Assessment of Malondialdehyde Belonging to Modulators and Substrates of the P-Glycoprotein Transporter Protein.

In the study on cells of the Caco-2 line, the affiliation of malondialdehyde (MDA) to modulators and substrates of P-glycoprotein (Pgp) was assessed, and the biological role of Pgp in conditions of oxidative stress (OS) was studied. MDA was used at concentrations of 10, 50, 100, and 150 µM; OS was simulated by incubation with hydrogen peroxide (H2O2) at concentrations of 0.1-100 µM for 24 h. The relative amount of Pgp was evaluated by the Western blot hybridization, and the activity was estimated by the transport of its substrate fexofenadine (HPLC with UV detection, HPLC MS/MS). In this study, it was shown that MDA at concentrations of 10 and 50 µM and exposure duration of 24 h increases the relative amount and activity of Pgp by acting through CAR and PXR, and MDA can be transported by Pgp. The induction of Pgp under the action of MDA during the development of OS can have a protective significance, ensuring the removal of the peroxidation product from cells into the extracellular space and thereby increasing the viability of cells.

[Original and generic drugs: what does the clinician need to know?] / Original'nye i vosproizvedennye lekarstvennye preparaty: chto nuzhno znat' klinitsistu?

In the review article modern approaches to testing and registration of generic drugs are discussed. The article presents the history of the formation of the methodology for testing generic drugs and the current legislation of the Russian Federation. The stages of confirmation of equivalence of original and generic drugs are described: pharmaceutical equivalence, bioequivalence and therapeutic equivalence. The methods of assessing bioequivalence - as the main research in the registration of generic drugs - are discussed in detail. Using the example of the original neuroprotector - Mexidol (ethylmethylhydroxypyridine succinate) and its generics, it is described how legislative acts are implemented in practice. It is concluded that not all generic drugs are interchangeable for the original drug.

[Functioning of pregnan X receptor under conditions of nitrosative stress]. / Funktsionirovanie pregnan X retseptora v usloviiakh nitrozativnogo stressa.

Pregnan X receptor (PXR) is a nuclear receptor that plays an important role in the regulation of the expression of biotransformation and metabolic enzymes. The functioning and possible mechanisms of PXR regulation under conditions of nitrosative stress have not been studied, which served as the purpose of this study. The work was performed on Caco-2 cells. Nitrosative stress (NS) was modeled using S-nitrosoglutathione (GSNO) at concentrations of 1 µM, 10 µM, 50 µM, 100 µM, and 500 µM and incubation during of 3 h, 24 h, and 72 h. The amount of PXR was assessed byWestern blotting. Incubation of Caco-2 cells with all concentrations GSNO for 3 h led to a decrease in the amount of PXR. Incubation with GSNO (1-50 µM) for 24 h was accompanied by an increase in the amount of PXR, while at a concentration of 100 µM this indicator did not significantly differ from the control, at a concentration of 500 µM it was lower. Prolonged incubation (72 h) enhanced NS and led to a normalization (1 µM GSNO) or a decrease of the PXR level (10-500 µM GSNO). The induction of PXR by GSNO was mediated by the effect of the nitrosative stress product bityrosine on the transcription factor. It was shown that bityrosine at concentrations of 0,4 mM and 1 mM increased the amount of PXR.

Expression of Apoptotic Markers Bcl-2 and Bax in the Vascular Wall.

The aim of the study was to assess the levels of Всl-2 and Bax proteins in the vascular wall and their correlation with serum cholesterol in patients with stage III-IV atherosclerosis obliterans of lower limb arteries. Materials and Methods: The study included 32 patients with stage III-IV atherosclerosis obliterans of the lower limb. Samples of intraoperative material (all three layers of the vascular wall) including an atherosclerotic plaque (AP) were taken during primary open surgery on major leg arteries. As a control, we used samples of the arterial wall without visible signs of atherosclerosis. Based on AP ultrasonography, the patients were divided into two groups: with APs of mixed echogenicity and with hyperechoic (calcified) AP. The vascular samples were crushed and homogenized for further measurements of Всl-2 and Bax proteins; in a separate setup, cholesterol in blood serum was measured. Results: In patients without atherosclerotic changes, the level of the anti-apoptotic protein Bcl-2 in the arterial wall was 1.25 ng/mg, and that of the pro-apoptotic protein Bax - 4.7 ng/mg. In the case of APs of mixed echogenicity, the expression of Bcl-2 was 1.8 ng/mg (p=0.143) and that of Bax - 5.1 ng/mg (p=0.834), with no significant differences from AP-free vascular wall samples. In the arterial wall containing a heterogeneous calcified AP, the expression of Bcl-2 was 0.9 ng/mg (p=0.143), In contrast, the level of Bax was 6.8 ng/mg, which showed its significant increase as compared with the non-AP controls (p=0.02). In the cases with predominantly hyperechoic AP, the expression of Bcl-2 was significantly lower (p=0.036), and that of Bax - significantly higher (p=0.036) in comparison with AP of mixed echogenicity. In patients with hyperechoic AP, we found a negative correlation between the Bax and Bcl-2 values ( r=-0.315) and a positive correlation between the Bax expression and serum cholesterol (r=0.617). Conclusion: In arterial walls with hyperechoic (calcified) APs, the expression of anti-apoptotic protein Bcl-2 is reduced, and that of pro-apoptotic protein Bax is increased, which indicates the apoptosis activation in advanced atherosclerotic lesions. In patients with such APs, elevated cholesterol levels directly correlate with the increased expression of pro-apoptotic Bax protein (r=0.617).

[Evaluation of female sex hormones influence on the protein-transporter p-glycoprotein functioning in vitro]. / Otsenka vliianiia zhenskikh polovykh gormonov na funktsionirovanie belka-transportera glikoproteina-P in vitro.

The effects of female sex hormones estradiol and progesterone on P-glycoprotein (Pgp) functioning have been investigated using Caco-2 cells. Pgp activity was analyzed in a transwell system by the transport of its substrate, fexofenadine. The amount of the transporter protein was analyzed by enzyme immunoassay. Incubation of Caco-2 cells with 10 µM estradiol and incubation for 3 days increased activity and synthesis of Pgp. Moreover, this effect was suppressed by the inhibitor of the constitutive androstane receptor (CAR) CINPA 1. Incubation of these cells with 100 µM progesterone for 3 days increased Pgp synthesis, but its activity remained unchanged due to non-genomic (direct) inhibition of Pgp molecule by gestagen. The pregnan-X receptor inhibitor (PXR), ketoconazole suppressed the inducing effect of progesterone on Pgp synthesis. The combination of 10 µM estradiol and 100 µM progesterone increased Pgp synthesis, but did not increase the transporter protein activity, due to direct inhibition of the Pgp molecule by progestogen. Thus, it was found that estradiol increased activity and synthesis of Pgp by stimulating CAR, and progesterone stimulated transporter protein synthesis by activating PXR.

[An effect of mexidol on the expression of the transcription factor Nrf2 in the rat cerebral cortex in ischemia]. / Vliianie meksidola na ékspressiiu transkriptsionnogo faktora Nrf2 v kore bol'shikh polusharii golovnogo mozga pri éksperimental'noi ishemii.

AIM: To study an effect of the antioxidant and antihypoxant mexidol (ethylmethylhydroxypyridine succinate) on the transcription factor Nrf2 expression in neuronal nucleis of frontal cortex cells autor the common carotid artery unilateral occlusion. MATERIAL AND METHODS: The study was performed on 64 male Wistar rats. The Nrf2 expression was determined immunohistochemically. RESULTS: Single intraperitoneal mexidol (120 mg/kg b.w.) infusion and oral (100 mg/kg p.w. thrice a day for 14 days) administration of mexidol did not affect Nrf2 expression. Unilateral common carotid artery occlusion led to the increase in Nrf2 expression 4 h and 5 days after occlusion. Oral administration of mexidol in dose of 100 mg/kg b.w. thrice a day for 14 days before and after ischemia increased Nrf2 expression on the 4th h and on the 12th day in comparison with intact animals. Nrf2 expression was higher after 4 h and 12 days in comparison with the control occlusion group. CONCLUSION: Mexidol increases Nrf2 expression in the frontal cortex of rats not under normal conditions but in common carotid artery unilateral occlusion.

[A modern concept of antihypoxic and antioxidant effects of mexidol]. / Sovremennye predstavleniia ob antigipoksicheskom i antioksidantnom éffektakh meksidola.

The review article presents a modern concept of the mechanism of antioxidant and antihypoxic action of the original drug mexidol (2-ethyl-6-methyl-3-hydroxypyridine succinate). The direct antioxidant activity of mexidol has been described, which consists in the ability of the drug to inactivate free radicals and increase the activity of the antioxidant enzymes glutathione peroxidase and superoxide dismutase in vitro. The results of the indirect antioxidant activity of mexidol, manifested in the increased expression under the ischemia of the transcription factor Nrf2, responsible for the cell resistance to oxidative stress are presented. The antihypoxic action of mexidol due to the presence of succinic acid in its molecule, which on the one hand supports the work of the Krebs cycle succinate oxidase under oxygen deficiency conditions, and on the other hand, binds to its specific receptors (GPR91), and starts a cascade of biochemical reactions that increases the body's resistance to lack of oxygen is discussed. The results of preclinical and clinical studies confirming the antioxidant and antihypoxic effects of mexidol are summarized.

[Mexidol effect on the factor induced by hypoxia HIF-1α expression in the rat cerebral cortex in ischemia]. / Vliianie meksidola na ékspressiiu faktora, indutsiruemogo gipoksiei HIF-1α, v kore bol'shikh polusharii golovnogo mozga krys pri ishemii.

The aim of the research - to study the Mexidol (ethylmethylhydroxypyridine succinate) effect on the factor induced by hypoxia (HIF-1α) expression in the frontal cortex of the brain in its ischemia. MATERIAL AND METHODS: The work was performed on the 64 male Wistar rats. The expression of HIF-1α was determined immunohistochemically. RESULTS AND DISCUSSION: It is determined that single intraperitoneal administration of Mexidol at a dose 120 mg/kg and oral administration at a dose 100 mg/kg three times a day for 14 days is not affected the expression of HIF-1α. Unilateral occlusion of the common carotid artery increases the expression of HIF-1α at 4 hours after the occlusion. Oral administration of Mexidol at a dose 100 mg/kg three times a day for 14 days before and after ischemia increases the expression of HIF-1α after 4 and 12 hours in comparison with the norm, on the 5th day in comparison with occlusion control. Thus, it has been established that Mexidol increases the expression of HIF-1α in the frontal cortex of rat brain not under normal conditions, but in unilateral occlusion of the common carotid artery.

[A role of P-glycoprotein in neurology]. / Rol' glikoproteina-R v nevrologii.

On the basis of the analysis of literature data, the authors show a role of P-glycoprotein in the pathogenesis, pharmacotherapy and a prophylaxis of neurologic diseases (Alzheimer's disease, Parkinson's disease, epilepsy, stroke).