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.

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.

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.

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.

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.

[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.

[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.