[The original novel nootropic and neuroprotective agent noopept]

The paper describes pharmacological properties of the new nootropic drug noopept created using an original approach based on the imitation of a nonpeptide nootrope structure by means of the short-peptide design. In particular, the structure of pyracetam was designed using dipeptide nootropes. Experimental investigations of noopept (N-phenylacetyl-L-polyglycine ethyl ester) showed that the new drug exceeds pyracetam both with respect to the effective dose level (1000 times lower for noopept than for pyracetam) and in the spectrum of mnemotropic activity. In contrast to pyracetam facilitating only the early stages of the memory process, noopept positively influences the memory consolidation and retrieval steps as well. The new drug produces an additional selective anxiolytic action. The pronounced neuroprotective effect of noopept was demonstrated both in vivo (in cases of various forms of brain ischemia) and in vitro (on various neuronal models). The drug action is based on the antioxidant effect, the antiinflammatory action, and the ability to inhibit the neurotoxicity of excess calcium and glutamate, and to improve the blood rheology. It was established for the first time that the activity of noopept is retained both upon parenteral introduction and upon peroral administration, which is a principal advantage of this proline-containing dipeptide over other, more complex peptides. This property provided a basis for the development of a medicinal form of noopept for peroral usage. At present, noopept tablets (noopept 5 and 10 mg) are under clinical assessment as a means of treating cognitive deficiency of cerebrovascular and post-traumatic origin.

[Prospects of the search for novel anxiolytics]

Based on an analysis of the present-day knowledge of the pathogenesis of stress, neurosis, and neurosis-like states, the paper highlights the spectrum of pharmacological activity and the mechanisms of action of the commonly used anxiolytics. The main trends in the search for new anxiolytics in Russia and abroad are considered and the most promising directions are indicated. A special attention is devoted to drugs of the new generation, representing agents with different tropicity toward benzodiazepine and GABA receptor subunits, endogenous and exogenous membrane regulators of these receptors, glutamatergic and serotoninergic anxiolytics, hormones, nucleic acid metabolites, substances influencing energy metabolism, neuropeptides with anxiolytic action, etc. A new classification of anxiolytics based on the mechanisms of their action is proposed. A special focus is placed on the achievements of Russian pharmacologists in the design and development of the new generation of anxiolytics.

[Mutagen effects in various organs and tissues of rats studied by fluorometric analysis]

The method of fluorometric analysis for DNA unity (FADU) was used to study the genotoxic effects of cyclophosphamide in rats. The dose dependence and time variation of mutagenicity manifestations in various organs and tissues of the experimental animals was studied. It was established that FADU results agree with the data obtained by conventional methods of cytogenetics. The results confirm the expediency of using FADU for the preclinical investigations of drugs.

[Selank and short peptides of Taftsin derivatives in regulation of adaptive behavior of animals in stress]

Effects of 10 peptides, tuftsin and Selank derivatives upon behavior during emotional stress induced by conflict situation, were studied in Balb/c and C57BL/6 male mice with genetically determined opposite types of emotional stress reaction, in white male mice and in Wistar male rats divided into different groups according to the type of emotional reactivity. Positive effects of some peptides upon the adaptive behavior of animals in stress situation were demonstrated. Individual physiologically important effects depending on molecular structure of the peptides under study and/or their fragments, possible products of degradation, were revealed. The results obtained confirm the perspectives of aimed synthesis of peptides with definite pharmacological activity, which are not ksenobiotics and will have no side effects.

Endogenous dipeptide cycloprolylglycine shows selective anxiolytic activity in animals with manifest fear reaction

Experiments on two mouse strains with opposite reactions to emotional stress showed selectivity of the anxiolytic effect of endogenous dipeptide cycloprolylglycine. In the open field test cycloprolylglycine (0.01-0.10 mg/kg intraperitoneally) dose-dependently (1.8-2.1-fold) increased motor activity of BALB/c mice with manifest fear reaction and had no effect on C57Bl/6 mice with active behavior. The content of endogenous cycloprolylglycine in mouse brain correlated with the type of emotional stress reaction: its content in the brain of C57Bl/6 mice 1.5 times surpassed that in BALB/c mice. It is concluded that cycloprolylglycine is involved in the endogenous regulation of fear reaction.

[Multicomponent antithrombotic effect of the neuroprotective prolyl dipeptide GVS-111 and its major metabolite cyclo-L-prolylglycine]

The experiments in vivo showed that the new nootropic prolyl-containing GVS-111 produces an antithrombotic effect, influencing various stages of the blood coagulation process. GVS-111 exhibits anticoagulant and fibrinolytic properties and enhances fibrin destabilization by reducing the XIIIa factor activity. These effects are manifested upon both intraperitoneal (1 mg/kg) and peroral (10 mg/kg) administration of GVS-111 (in both cases, a single daily treatment over a period of 10 days). The same effects (anticoagulant, fibrinolytic, antifibrin-stabilizing) were observed in in vitro experiments with both GVS-111 (10(-3)-10(-6) M) and its main metabolite cyclo-L-prolylglycine (up to 10(-10) M). In addition, the latter metabolite exhibited an antiaggregant effect. The antithrombotic activity of GVS-111, together with previously established neuroprotector properties, low toxicity, and the absence of complications, makes this compound a promising antistroke drug.

[Effect of the novel dipeptide nootropic agent noopept and its metabolite cyclo-L-prolylglycine on the transcallosal evoked potential in the rat brain]

The effect of new nootropic dipeptides--noopept (N-phenylacetyl-L-prolylglycine, GVS-111) and its metabolite (cyclo-L-prolylglycine)--and a standard nootrope piracetam on the transcallosal evoked potential (TEP) in rat brain was studied. In the dose range from 150 to 300 mg/kg, piracetam increased the TEP amplitude, which exhibited a maximum after 1.5-2 h and then gradually decreased. Both noopept and cyclo-L-prolylglycine also increased the TEP amplitude, which attained a plateau and retained this level over the entire observation time (above 3.5 h). All the nootropes studied increased both components of the evoked potential. Piracetam and cyclo-L-prolylglycine led to an approximately equal increase in both waves, while noopept induced a somewhat greater increase in the negative TEP wave amplitude. It is suggested that the positive effect of noopept and cyclo-L-prolylglycine upon the interhemispheric signal transfer (indicated by the improved transcallosal response) can be considered as a potential neurophysiological basis for a positive drug influence on the behavioral level.

[Anti-inflammatory properties of noopept (dipeptide nootropic agent GVS-111)]

It is established that single intravenous (0.5 and 5 mg/kg, p.o.) or single peroral (10, 50, 100 mg/kg) and prolonged peroral (5 mg/kg, over 10 days) administration of noopept produces a dose-dependent inhibition of the model inflammatory response to concanavaline A in CBA mice. Intravenously injected (5 mg/kg) noopept suppressed the acute nonimmune carrageenan-induced foot inflammation in rats by 62.2% within 3 h. The most pronounced antiinflammatory effect of dipeptide was observed on the model of adjuvant arthritis in rats, where the drug administered over 25 days in a daily dose of 0.5 mg/kg (i.m.) or 5 mg/kg (p.o.) significantly reduced the chronic immune inflammation (on the 12th day, by 94.0 and 74.1%, respectively). The in vitro experiments with neutrophilic leukocytes of F1(CBA.C57BL/6) mice treated with noopept in a single dose of 5 mg/kg (i.v.) showed a 5- to 6-fold suppression of the hemiluminescence stimulated by opsoinized zymosan or phorbolmyristate acetate. It is suggested that the antiinflammatory activity of noopept is probably related to its antioxidant properties.

[Effect of plant melanin pigment on the clastogenic effects of chemical mutagens in mice]

The chromosome aberration assay in the bone marrow cells of C57BL/6 mice showed that melanin pigment (MP) in a dose range from 0.01 to 10 mg/kg does not influence the clastogenic effect of dioxidine (200 mg/kg, i.p.), while reducing the clastogenic effect of cyclophosphamide (20 mg/kg, i.p.) by a factor of 1.5-4 in various treatment regimes depending on the mutagen injection time.

Proline-containing dipeptide GVS-111 retains nootropic activity after oral administration

Experiments on rats trained passive avoidance task showed that N-phenyl-acetyl-L-prolyl-glycyl ethyl ester, peptide analog of piracetam (GVS-111, Noopept) after oral administration retained antiamnesic activity previously observed after its parenteral administration. Effective doses were 0.5-10 mg/kg. Experiments on a specially-developed model of active avoidance (massive one-session learning schedule) showed that GVS-111 stimulated one-session learning after single administration, while after repeated administration it increased the number of successful learners among those animals who failed after initial training. In this respect, GVS-111 principally differs from its main metabolite cycloprolylglycine and standard nootropic piracetam.

[Features of the stress reaction in rats with genetically-determined emotionality (from EEG indicators)]

The features of the EEG spatial organization in two rat strains, i.e., with expressed emotional reactions (Maudsley reactive, MR) and less reactive (Maudsley nonreactive, MNR) were compared in two stress situations: during exposure to the action of pain (P) (i.p. injection of 0.9% NaCl solution) and during 24-hour water deprivation (D). Multichannel EEG recording (24 derivations) and their multiparametric estimation (840 signs) made it possible to differentiate characteristic features of the EEG spatial organization in rats with initially increased emotional reactions and passive behavioral strategy during exposure to stress. In both stress-inducing conditions, an increase in crosscorrelation and coherence between cortical potentials in parallel with rise of the spectral power in the range of high-frequency theta and its drop in the range of EEG high-frequency band was observed in the MR rats. The MNR rats showed the opposite changes. Different reactivity of the ratio between the coherence and spectral power of potentials was observed in two strains of rats. This index characterizes the level of the information-energy component of the spatial organization of cortical potentials. It is suggested that different character of the EEG changes reflects the features of interhemispheric relations, information-energy processes, and cortical regulation of autonomic processes in the system of adaptive stress reactions at different levels of emotionality and behavioral strategy.

[Effect of a novel antimigraine preparation tropoxin on EEG of MR and MNRA rats]

Effect of the new antimigraine drug tropoxin on the EEG profile was studied in MR and MNRA rats with genetically determined high and low levels of emotionality, respectively. In MR rats, tropoxin decreased the number of the bioelectric activity parameters changed by the stressor action (0.9% NaCl, i.p.). The drug reduced the spectral power in the EEG delta band, and increased that in the theta, beta-1, and beta-2 bands. This was evidence of the central stimulating action and the possible enhancement of the exploratory activity. In MNRA rats no changes in bioelectric activity were observed in the low-frequency delta and theta bands, while the spectral power in the beta-1, and beta-2 bands showed a decrease. It was concluded that a neural component is present in the mechanism of the tropoxin action, which may play an important part in the therapeutic effect of the new drug.

[Effect of novel anxiolytic agent aphobazole on coherence of the brain biopotentials in MR and MNRA rats]

Effect of the anxiolytic drugs afobazole, diazepam, and chlordiazepoxide on the cortical biopotential coherency was studied in MR and MNRA rats with increased and decreased level of emotionality, respectively. Afobazole increased a difference in the biopotential coherency between rats of the two lines in the range of EEG theta, alpha, and beta rhythms. In the subrange of dominating theta activity (6.00-7.25 Hz), this effect took place at the expense of reduced coherency in MNRA rats in the absence of changes in the MR line. Afobazole decreased the biopotential coherency in the alpha activity band (7.5-8.25 Hz) in the rats of both lines. This is indicative of the presence of a CNS-stimulating component in the pharmacological activity spectrum of afobazole. The expediency of using afobazole in patients with different levels of anxiety is discussed.

Anxiolytic activity of endogenous nootropic dipeptide cycloprolylglycine in elevated plus-maze test

Testing in an elevated plus-maze revealed dose-dependent anxiolytic activity of piracetam analog cycloprolylglycine. Intraperitoneal injection of this agent (0.05 mg/kg) 9-fold prolonged the time spent in open arms compared to the control, without affecting the total motor activity. This effect was stereo-selective: D-enantiomer in doses of 0.05 and 0.1 mg/kg was inactive. Therefore, cycloprolylglycine is similar to piracetam in not only nootropic, but also anxiolytic activity. The existence of an endogenous system responsible for the co-regulation of memory and anxiety is hypothesized.

[Is it possible to predict individual stress resistance by evaluating low dose benzodiazepine effect in modeled emotional stress]

Individual effects of the benzodiazepine tranquilizers phenazepam and gidazepam were studied in neurotic patients and in healthy volunteers tested for the operatory performance under emotiogenic conditions. It was found that manifestations of the tranquiliactivating, tranquilizing, and tranquilisedative effects depend on the individual sensitivity types of the patients and volunteers. The activating manifestations were most pronounced in hypostenic patients, while the sedative action was most significant in hyperstenic persons. The tranquilisedative effect of a single test dose of gidazepam (20 mg) allows predicting a low efficacy of the log-term therapy with benzodiazepines studied. In a group of 40 healthy volunteers, a single 20-mg dose of gidazepam increased the operatory under emotiogenic conditions performance in 19 persons and decreased the results in 12 cases. Volunteers in the first group were characterized as less stress-resistant with respect to a combination of psychological, psychophysiological, and hormonal-biochemical parameters as compared to the second group. It was concluded that the benzodiazepine test is worth of further elaborating as a means of predicting the stress resistance based on the effect of a model benzodiazepine tranquilizer under laboratory conditions.

[Clinical study of the selective anxiolytic agent afobazol]

A standard clinical trial including pharmaco-EEG investigation of the new selective anxiolytic afobazole was performed on a group of 30 patients with anxiety and anxious-asthenic disorders and premorbid individual asthenic profile traits. Afobazole exhibits the anxiolytic action with an activating component in the absence of sedative and myorelaxant effects. The clinical trial results confirmed good prospects of using the experimentally validated pharmacogenetic concept of anxioselectivity as a methodological approach to the design of new drugs possessing selective anxiolytic properties.

[3H-Diazepam binding in the brain of intact animals with various reactivity to emotional stress]

Open-field tests revealed a significant decrease in the degree of H3-diazepam binding in the brain of BALB/c mice and MR rats. No such effects were observed in the C57BL/6 and MNRA strains. No interstrain distinctions were observed in the intact animals.

[Predicting individual reactions to emotional stress and benzodiazepine tranquilizers]

The results of pharmacogenetic experiments revealed specificity of the emotional-stress reactions (ESR) in the inherited deterministic type of behavior and showed dependence of the benzodiazepine tranquilizer action on the ESR phenotype. Based on these data, we carried out experiments with a group of volunteers performing operator functions in a model of emotional-stress conditions. The results of these experiments allowed the operators to be divided into stress-resistant and stress-affected groups. The results of the data processing by methods of multidimensional statistics showed possibility of predicting the ESR phenotype and the qualitative effect of phenazepam (0.5 mg. p.o.) based on the individual topological and hormonal-biochemical characteristics of operators.

[State of hemopoiesis under exposure to low doses of ionizing radiation and emotional stress during treatment with anxiolytic aphobazole]

In experiments on rats it was found that aphobazole administered before emotional stress is capable to stop violations of adaptive reactions and compensator capabilities of a hemopoietic system in conditions of development of an emotional stress in early terms after gamma-irradiation with a dose of 0.9 Gy.

Effects of beta-carotene and aspartame on clustogenic activity of cyclophosphamide and dioxidine in mice

Antimutagenic effects of combination of aspartame (0.4 and 4 mg/kg) and beta-carotene (0.15-15 mg/kg) were studied by estimation of chromosome aberrations in bone marrow cells of C57Bl/6 mice. Single and 5-day treatment with this combination decreased the clastogenic effects of dioxidine and cyclophosphamide and produced a more potent and universal antimutagenic effect than its constituents.

[Modification by lacidipine of the clastogenic effect of dioxidine in vivo]

The influence of lacidipine (0.1-10 mg/kg, intragastric) on the clastogenic effect of dioxidine (100 and 200 mg/kg, i.p.) under conditions of their single and repeated (five-fold, 24-h interval) administration was studied by the chromosome aberration assay in the metaphase bone marrow cells of BALB/c and C57BL/6 male mice. It was found that single (5 or 10 mg/kg) and repeated (10 mg/kg) introduction of lacidipine enhances the clastogenic effect of dioxidine in both genotypes. At the same time, a single treatment of C57BL/6 mice with 0.1 and 1 mg/kg of lacidipine sometimes significantly reduced the clastogenic effect of dioxidine (200 mg/kg). Thus, lacidipine exhibits a comutagen effect in vivo when administered at large doses (5 and 10 mg/kg) but not at small doses, where the drug sometimes acted as antimutagen in C57BL/6 mice.

Multidimensional assessment of differences in monoamine metabolism in C57BL/6 and BALB/c mice

Monoamine metabolism in the hypothalamus and striatum of BALB/c and C57Bl/6 mice (intact and stressed in the open field test) was studied using single- and multidimensional statistical methods. It is suggested that the revealed difference in neurotransmitter metabolism is associated with genetically controlled behavior of these animals under conditions of emotional stress. The results of discriminant analysis suggest that the regulation of monoamine metabolism during emotional stress is genetically determined.