[COMPARISON OF CHRONIC ANTICONVULSANT ACTIVITY AND SAFETY OF IEM-2062, SODIUM VALPROATE AND ME-MANTINE IN THE PENTYLENETETRAZOL KINDLING MODEL IN RATS].

IEM-2062 [1-(6-aminohexylamino)-1-phenylcyclohexyl dihydrochloride], causing a combined block NMDA and AMPA receptors, after chronic oral administration in doses, respectively, 0.3 and 3 mg/kg, induce maximal anticonvulsant effect in the pentylenetetrazol kindling rats because decrease the number of completely kindling rats by 100 %, and also decrease in 2.5-3.3 times the average severity of clonic-tonic kindling seizures. IEM-2062 causes significant anticon- 299 vulsant effects in the widest range of doses, 1-48 mg/kg, which is 24-22 times more than that of memantine (12-20 mg/kg) and sodium valproate (100-200 mg/kg). Sodium valproate and memantine cause significant disturbances of locomotor activity in the «open field¼ test in doses causing maximal anticonvulsant effect in the kindling rats. At the same time IEM-2062 cause disturbance of locomotor activity only in very high dose of 92 mg/kg, which exceeds in 30.7 times the dose causing the maximum anticonvulsive effect in the kindling rats. Thus, IEM-2062 reduces the severity of kindling seizures in 1.7-1.9 times stronger than sodium valproate and memantine and also by 30.7 times is safer than sodium valproate and memantine.

[NOTHROMBEL EFFECT ON THE FORMATION OF PLATELET-LEUKOCYTE COMPLEXES INDUCED BY THROMBIN].

The effects of the Nothrombel on the formation of platelet-leukocyte complexes (PLCs) induced by thrombin was studied. It was shown, that Nothrombel dose-dependently inhibited the formation of PLCs. Its activity is higher than the activity of the comparison compounds Aspirin. The half maximal effective concentration (EC50) for Nothrombel is 1.75 mMol/mL, for Aspirin is much more than 2.5 mMol/mL. The inhibition mechanism of the PLCs formation by Nothrombel caused by the ability of this drug to inhibit the P-selectin translocation on the platelet membrane, the expression of membrane complex GPIb-IX-V, the mobilization of cytoplasmic calcium in platelets, as well as, apparently, its inhibitory effect on platelet P2Y12 purine receptors.

Molecular mechanism of modulation of nociceptive neuron membrane excitability by a tripeptide.

Using the whole-cell patch-clamp method, the ability of arginine-containing tripeptide Ac-RER-NH2, dipeptide Ac-RR-NH2, and free Arg molecule to modulate the membrane excitability of nociceptors was studied. Extracellular Ac-RER-NH2 upon interaction with the outer membrane of the nociceptive neuron decreases the Zeff value of the activation gating system of Nav1.8 channels. Thus, the tripeptide Ac-RER-NH2 can be considered as a new effective and safe analgesic.

[NOTHROMBEL EFFECT ON THE EXPRESSION OF MEMBRANE COMPLEX GPIb-IX-V PLATELETS ACTIVATED BY THROMBIN].

The influence of Nothrombel on the expression of membrane complex GPIb-IX-V of platelets activated by thrombin was studied. It is established that Nothrombel reduced thrombin-induced expression of complex GPIb-IX-V on the membrane of the activated platelets. The inhibitory activity of Nothrombel on the expression of GPIb (CD42b) was comparable to its activity with respect to GPIX (CD42a) and is equal to 43 %. With regard to GPV (CD42d) inhibitory effect of the drug was less pronounced and is equal to 22 %. The possible targets for Nothrombel are activation of thromboxane signaling pathway, as well as GPIb-IX-V receptors of platelets itself.

Comparison of Pharmacological Potency and Safety of Glutamate Blocker IEM-1913 and Memantine.

Adamantane-containing glutamate blocker IEM-1913 (1-amino-4-(1-adamantane-amino)-butane dihydrochloride) equals to memantine in antiparkinsonian potency, but surpasses it in anticonvulsive, antidepressant, and analgesic activities. Moreover, its use is less toxic and safer. IEM-1913 produces significant pharmacological effects at a wide concentration diapason (0.03-1.00 mg/kg), while memantine is effective within a narrow range only (15-20 mg/kg). High pharmacological efficacy and low toxicity of IEM-1913 can be explained by the fact that in contrast to monocationic selective NMDA antagonist memantine, the dicationic glutamate blocker IEM-1913 produces a combined block of cerebral NMDA and AMPA receptors.

[Stimulation of gastric mucosa afferents by phenylephrine potentiates anticonvulsive and eliminates sedative action of sodium valproate in the pentylenetetrazol kindling model in rats].

Sodium valproate after chronic intragastric administration in the high dose of 100-200 mg/kg eliminates generalized clonic-tonic pentylenetetrazol seizures in 100 % of rats, but only in 33-57 % of rats it prevents local clonic kindling seizures. Strong sedation is induced by the specified doses of sodium valproate. The combined oral chronic administration of phenylephrine in threshold, noneffective alone dose of 0.2 mg/kg and sodium valproate in high doses of 100 mg/kg and 200 mg/kg potentiates anticonvulsive action of sodium valproate, because prevents both clonic-tonic kindling. seizures in 100 % of rats and clonic kindling seizures in 86-100 % of rats, and also it increases in 1.7-1.9 times anticonvulsive activity of valproate. The specified combinations of sodium valproate with phenylephrine do not produce the sedative side effect. The basis of the mechanism of potentiation of anticonvulsive action and elimination of sedative action of sodium valproate in high doses is the stimulation of gastric mucosa afferents by phenylephrine.

Combined blockade of NMDA and AMPA receptors prevents acute kainate seizures and chronic kainate lethality in rats.

Single intramuscular injection of selective of NMDA receptor blocker memantine in the maximum dose of 20 mg/kg prevented the development of acute generalized tonic-clonic kainate seizures in 60% rats, but did not alleviate clonic kainate seizures and prevented chronic kainate lethality in only 30% rats. Intramuscular injection of NBQX, a selective blocker of AMPA receptors (10 mg/kg), produced more pronounced anticonvulsant and neuroprotective effects: it prevented generalized kainate seizures and chronic kainate lethality in 100 and 80% rats, respectively. However, even the high dose of NBQX prevented the clonic kainate seizures only in 30% rats. The intramuscular injection of novel agent IEM-2121 (0.03-1.00 mg/kg) known to block both AMPA and NMDA receptors, prevented the clonic kainate seizures only in 50-70%, although it precluded the chronic kainate lethality in 100%.

[Creatine in a metabolism of cell and its protective action at brain ischemia].

The aim of this review was the discussion of creatine involvement in metabolism of nervous tissue cells. The questions of creatine penetration through the blood brain barrier and creatine transporter expression were raised. Also mechanisms of creatine protective effect were considered at experimental models of brain ischemia. It was shown that creatine was involved in energy metabolism (creatine phosphate synthesis), inhibition of excitotoxicity. Besides it had antioxidant and antiproliferative effects. The creatine delivery problem was also discussed. Synthesis of substances capable to get through the blood brain barrier without CRT was the possible solution of the problem. The most perspective substances were creatine amides apparently capable to move through cell membranes without amino acid transporters. Prospects of their application were discussed.

[Combined blockade of AMPA- and NMDA-receptors has maximum effect to eliminate development of pentylenetetrazole-induced kindling in rats].

Peroral chronic administration the standard antiepileptic drug sodium valproate in a dose of 200 mg/kg eliminates development of generalized clonic-tonic pentylenetetrazol kindling seizures in 100% of rats, but only in 57% of rats this treatment prevents clonic kindling seizures. In the specified dose sodium valproate decreases in 1.7 times average severity of pentylenetetrazol kindling seizures compare with control. IEM-2121, causing combined blockade of NMDA- and AMPA-glutamate receptors, as well as IEM-1676, which also blocks AMPA-, NMDA- and N-cholinoreceptors, both after peroral chronic administration in a doses 10 mg/kg and 20 mg/kg accordingly, possess higher, than sodium valproate, anticonvulsant activity because reduce average severity of pentylenetetrazol kindling seizures in 2.4-2.7 times in comparison with control and prevents clonic kindling seizures in 87% of rats. Combined blockade of AMPA- and NMDA-receptors and perhars N-cholinoreceptors has maximum effect to eliminate epileptogenesis both clonic, and clonic-tonic pentylenetetrazol kindling seizures.

[Cytoprotective effect of creamide drug in the experimental model of the brain ischemia/reperfusion in rats].

The influence of creatine or its derivates on the cell energy potential may be one of the possibl approaches to induce neuroprotection. Effect of creamide (creatinylglycine ethylic ether fumarate) on the brain injury was studied in the experimental model of the brain ischemia/reperfusion in rats. The experiments were carried out in 14-20 weeks old male Wistar rats weighing 240-300 g, anesthetized by chloral hydrate (430 mg/kg). Creamide was administered intravenously at the doses of 50, 70, 140, and 280 mg/kg. For comparison phosphocreatine was used at the dose of 255 mg/kg. Creamide and phosphocreatine were administered intravenously (in volume of 1 ml within 5 min) 30 min before cerebral middle artery occlusion. Focal cerebral ischemia for 30 min was produced by endovascular suture occlusion with the subsequent 48 h reperfusion period. Creamide administration resulted in dose-dependent decrease of brain ischemic injury. Creamide administered at the doses of 140 and 280 mg/kg was more effective as compared with phosphocreatine (255 mg/kg). The data obtained open new perspectives for further research and development of new creatine-derived drugs with neuroprotective action.

[Effect of intragastric creatine glycine ethylic ether fumarate administration in a rat model of occlusive ischemia].

The aim of the study was to investigate neuroprotective effect of creatine glycine ethylic ether fumarate (creamide). The methods involved intragastric administration of creamide in doses of 30 and 50 mg/kg twice a day for 10 days. Focal 30 minutes cerebral ischemia model by endovascular suture occlusion of the middle cerebral artery in a rat with subsequent reperfusion period for 48 hours was produced. Assessment of creamide stability in gastric juice was performed. Ischemic lesion volume accompanying focal ischemia was visualized and determined. Similar infarction patterns had been found with histological methods. Garcia scale was used for clinical study of neurological deficit in rats. Our data suggest a significant neuroprotective effect of creamide in dosage 50 mg/kg administered twice a day which decreased brain lesion volume produced by ischemic and reperfusion injury.

[Amides of creatine: perspectives of neuroprotection].

We evaluated the efficacy of derivatives of creatine and amino acids (CrAA) for decreasing cerebral injury in rats with transient middle cerebral artery occlusion (MCAO). Neuroprotective effects of amides of creatine and glycine (CrGlyOEt), phenylalanine (CrPheNH2), thyrosine (CrTyrNH2), and GABA (CrGABAOEt) were investigated. Brain injury was evaluated on day 2 after transient MCAO using a TTC staining of brain slices. Compared with the MCAO control group, all the CrAms showed decreased cerebral injury (p < 0.05). However CrPheNH2, CrTyrNH2, and CrGABAOEt were toxic after intravenous administration and investigated only after intraperitoneal injection. CrGlyOEt did not show any toxicity at dose of 1 mmol/kg. These data evidenced that creatinyl amides can represent promising candidates for the development of new drugs useful in brain ischemia treatment.

Role of methionine in the active site of alpha-galactosidase from Trichoderma reesei.

alpha-Galactosidase from Trichoderma reesei when treated with H2O2 shows a 12-fold increase in activity towards p-nitrophenyl alpha-D-galactopyranoside. A similar effect is produced by the treatment of alpha-galactosidase with other non-specific oxidants: NaIO4, KMnO4 and K4S4O8. In addition to the increase in activity, the Michaelis constant rises from 0.2 to 1.4 mM, the temperature coefficient decreases by a factor of 1.5 and the pH-activity curve falls off sharply with increasing pH. Galactose (a competitive inhibitor of alpha-galactosidase; Ki 0.09 mM for the native enzyme at pH 4.4) effectively inhibits oxidative activation of the enzyme, because the observed activity changes are related to oxidation of the catalytically important methionine in the active site. NMR measurements and amino acid analysis show that oxidation to methionine sulphoxide of one of five methionines is sufficient to activate alpha-galactosidase. Binding of galactose prevents this. Oxidative activation does not lead to conversion of other H2O2-sensitive amino acid residues, such as histidine, tyrosine, tryptophan and cysteine. The catalytically important cysteine thiol group is quantitatively titrated after protein oxidative activation. Further oxidation of methionines (up to four of five residues) can be achieved by increasing the oxidation time and/or by prior denaturation of the protein. Obviously, a methionine located in the active site of alpha-galactosidase is more accessible. The oxidative-activation phenomenon can be explained by a conformational change in the active site as a result of conversion of non-polar methionine into polar methionine sulphoxide.

[Cyclic analogs of enkephalin with disulfide bridges between the second and fifth positions]. / Tsiklicheskie analogi énkefalina s disul'fidnym mostikom mezhdu 2-m i 5-m polozheniiami.

Biological activity of the enkephalin cyclic analogues with a disulphide bridge between second and fifth positions, and the dependence of the activity on the cycle size, disulfide bridge localization and configuration of the amino acid residues have been studied. The analogues were synthesized by chemical approach with the use of pentafluorophenyl esters. The cyclization was carried out at the C-terminal tetrapeptide stage by iodine in methanol after removing benzyl protecting groups from thiol groups of cysteine and homocysteine by sodium in liquid ammonia. The blocking activity in vitro (GPI and MVD tests) to the mu- and delta-receptors depends on cycle size, localization of disulphide bridge in the cycle, and amino acid configuration at second and fifth positions. Analogues with D-amino acids proved to be most active in vivo (analgesia, cataleptic activity, effect on frequency of heart contractions and body temperature). Conformational characteristics of enkephalin analogues were investigated by means of CD spectroscopy.