Background. The neuropeptide cycloprolylglycine (CPG) is an endogenous dipeptide analogue of the nootropic piracetam. It has been experimentally shown that CPG (designed and synthesized at the Federal State Budgetary Scientific Institution «Federal Research Center of Original and Promising Biomedical and Pharmaceutical Technologies») has a spectrum of pharmacological effects characteristic of piracetam. In studies aimed at studying the mechanisms of action of CPG, it was found that glutamate AMPA receptors and neutrophin Trk receptors are involved in the anxiolytic, neuroprotective and antihypoxic effects of CPG. However, the mechanism of nootropic action of CPG has not been studied.Objective. To test the hypothesis about the involvement of Trk receptors in the nootropic effect of CPG in a model of amnesia in mice induced by the administration of scopolamine.Material and methods. The nootropic activity of CPG (1 mg/kg, i.p.) was studied in a model of amnesia in mice induced by scopolamine (0.75 mg/kg, subcutaneously). A pharmacological inhibitory assay was used with the Trk receptor blocker K252a (5 μg/kg, i.p.). The severity of amnesia was assessed using the Novel Object Recognition (NOR) test.Results. Scopolamine was found to impair novel object recognition in mice in the NOR test. CPG prevents the development of amnesia induced by scopolamine, and Trk receptor blocker K252a blocks this effect.Conclusion. Trk receptors are involved in the nootropic effect of the neuropeptide CPG.

Background. Cyclo-L-prolylglycine (CPG) was designed and synthesized at the V.V. Zakusov as a topological analogue of the classical nootrop piracetam and was further identified as an endogenous compound. Previously, the nootropic effect of CPG was revealed in a model of retrograde amnesia in rats induced by electroconvulsive shock in the passive avoidance test (PAT). Objective. The aim of the present study was to investigate the nootropic effect of CPG under more physiological conditions in the absence of strong stressors. Methods. Amnesia in rats was modeled by intraperitoneal (ip) administration of scopolamine at a dose of 2 mg/kg. CPG was administered ip at doses of 0.1 and 1.0 mg/kg 15 minutes after scopolamine. Short- and long-term memory were recorded in the novel object recognition test. Results . It was found that scopolamine disrupted only the long-term memory of rats. CPG at a dose of 0.1 mg/ kg almost completely counteracted this impairment. CPG by itself had no effect on memory at both doses studied. Conclusion . Thus, CPG exhibits nootropic activity not only in the aversive conditions of the PAT and electroconvulsive shock-induced amnesia, but also in the neutral situation in the novel object recognition test, when the amnesia was caused by the administration of scopolamine.

Brain-derived neurotrophic factor (BDNF) is known to be involved in the pathogenesis of Alzheimer's disease (AD). However, the pharmacological use of full-length neurotrophin is limited, because of its macromolecular protein nature. A dimeric dipeptide mimetic of the BDNF loop 1, bis-(N-monosuccinyl-L-methionyl-L-serine) heptamethylene diamide (GSB-214), was designed at the Zakusov Research Institute of Pharmacology. GSB-214 activates TrkB, PI3K/AKT, and PLC-γ1 in vitro. GSB-214 exhibited a neuroprotective activity during middle cerebral artery occlusion in rats when administered intraperitoneally (i.p.) at a dose of 0.1 mg/kg and improved memory in the novel object recognition test (0.1 and 1.0 mg/kg, i.p.). In the present study, we investigated the effects of GSB-214 on memory in the scopolamine- and steptozotocin-induced AD models, with reference to activation of TrkB receptors. AD was modeled in rats using a chronic i.p. scopolamine injection or a single streptozotocin injection into the cerebral ventricles. GSB-214 was administered within 10 days after the exposure to scopolamine at doses of 0.05, 0.1, and 1 mg/kg (i.p.) or within 14 days after the exposure to streptozotocin at a dose of 0.1 mg/kg (i.p.). The effect of the dipeptide was evaluated in the novel object recognition test; K252A, a selective inhibitor of tyrosine kinase receptors, was used to reveal a dependence between the mnemotropic action and Trk receptors. GSB-214 at doses of 0.05 and 0.1 mg/kg statistically significantly prevented scopolamine-induced long-term memory impairment, while not affecting short-term memory. In the streptozotocin-induced model, GSB-214 completely eliminated the impairment of short-term memory. No mnemotropic effect of GSB-214 was registered when Trk receptors were inhibited by K252A.

Relevance. Depression and cognitive impairment are common complications of acute cerebrovascular accidents. Disorders of hippocampal neuroplasticity associated with a decrease in BDNF expression are considered as one of the causes of these complicatio ns. A dimeric dipeptide mimetic of the BDNF loop 4, (bis (N - monosuccinyl -L- seryl -L- lysine) hexamethylenediamide) (GS B-106) was created at the V.V. Zakusov Research Institute of Pharmacology. GSB - 106 demonstrated antidepressant, neuroprotective and neuroregenera-tive properties in in vivo experiments. Objective . Experiments were performed on 40 male rats Wistar weighing 2 40–280 g. Purpose of the study is to investigate the effect of GSB - 106 on depression - like behavior and memory impairments in rats induced by middle cerebral artery occlusion (MCAO). Material and methods . GSB - 106 was injected intraperitoneally at a dose of 0.1 mg/kg for 21 days after surgery. Depressive - like behavior was detected in the forced swimming test, and memory impairments – in the novel object recognition test. Conclusions . GSB - 106 is a promising compound for further development as a drug for the treatment of post - stroke depression and cognitive impairment.

Previously we have shown that the neuropeptide cycloprolylglycine is an endogenous positive modulator of AMPA receptors and assumed that the pharmacological effects of CPG are associated with the brain neurotrophic factor. In this paper, we have first demonstrated that DNQX, an inhibitor of AMPA receptors, and K252A, an ihibitor of Trk receptors, prevented the anxiolytic effect of CPG, which confirms the formulated hypothesis.

СИНТЕЗ ФАРМАКОЛОГИЧЕСКИ АКТИВНОГО АНАЛОГА ДИПЕПТИДНОГО МИМЕТИКА BDNF ГСБ-106 Н.М.Сазонова к.х.н., ФГБНУ «НИИ фармакологии имени В.В.Закусова» (Москва) А.В.Тарасюк науч.сотрудник, ФГБНУ «НИИ фармакологии имени В.В.Закусова» (Москва)

Dipeptide mimetic of the nerve growth factor (NGF) loop 4, hexamethylenediamide bis-(N-monosuccinyl-glutamyl-lysine) (GK-2), was synthesized at the V.V. Zakusov Scientific Research Institute of Pharmacology of the Russian Academy of Medical Sciences. GK-2 exhibited in vitro neuroprotective activity at nanomolar concentrations, was efficient in animal models of the Parkinsons disease, ischemic and hemorrhagic stroke, and global cerebral ischemia at doses of 0.015 mg/kg (intraperitoneally) and 10 mg/kg (per os). The mnemotropic effects of subchronic intraperitoneal administration of GK-2 on rat models of the Alzheimers disease are described in this paper. Dipeptide GK-2 at a dose of 1 mg/kg is found to decrease the habituation deficit induced by the septo-hippocampal pathway transsection and, at a dose of 0.5 mg/kg, to significantly prevent spatial memory impairment in Morris water maze induced by intracerebral injection of streptozotocin. Thus, GK-2, an original dipeptide mimetic of NGF, acts on models of the Alzheimers disease upon systemic administration.

Glycine stabilizes energetics of brain mitochondria under conditions of brain hypoxia in vivo modeled by ligation of the common carotid artery in rats. Hypoxia reduced respiratory control in brain cortex mitochondria from 7.7 ± 0.5 to 4.5 ± 0.3. Preliminary oral administration of glycine almost completely prevented this decrease. In both in vitro models of hypoxia, similar phosphorylation disturbances were detected in both cortical slices and isolated brain mitochondria; they were effectively prevented by glycine. Hypoxia activates H 2 O 2 generation in mitochondrial suspension. The process is signifi cantly reduced in the presence of 5 mM glycine. It is concluded that both in the model of hypoxia in vivo and during in vitro modeling of hypoxia in cortical slices and mitochondria, glycine acts as a protector inhibiting generation of reactive oxygen species in mitochondria and preventing energetics disturbances in brain mitochondria.

The behavioral and biochemical effects of a new dipeptide mimetic of the GK-2 nerve growth factor (NGF) have been studied on a model of chronic cerebral ischemia induced by permanent common carotid artery occlusion in rats. It is established that subchronic intraperitoneal injections of GK-2 (0.5 mg/kg) 4 h after surgery, followed by seven more injections made every 24 h, fully prevent the death of operated animals and reduces the development of habitation deficit (open-field test) and decrease in exploratory activity (novel object examination) two weeks after surgery, as well as fully restores the viability of cerebral cortex cells and decreases the hyperexpression of HSP70 in cerebral cortex.

An intraperitoneal injection of GK-2 (dipeptide mimetic of nerve growth factor, 0.01-5.00 mg/kg) 24 h before the adverse exposure reduced the severity of haloperidol-induced catalepsy in rats. This agent retained the activity after oral administration in a dose of 10 mg/kg. An intraperitoneal injection of GK-2 in a dose of 1 mg/kg reduced the severity of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-induced parkinsonian syndrome in mice. Administration of GK-2 45 min after haloperidol treatment was also followed by a decrease in the degree of catalepsy. The repeated intraperitoneal treatment with GK-2 in a dose of 1 mg/kg after intrastriatal injection of 6-hydroxydopamine was shown to prevent the development of apomorphine-induced rotations in rats.

Бондаренко Н.А., Воронцова О.Н., Зенина Т.А., Гудашева Т.А., Середенин С.Б. Влияние пептидомиметика фактора роста нервов ГК-2 на поведенческие и биохимические изменения, вызванные двусторонней перевязкой сонных артерий у крыс. Матер. III съезда фармакологов России. Психофармакол биол наркол 2007 Спец Вып; 7 (Ч 1, А–Л): 1-161 7 –1-161 8 (Тез 84 ) Старение и цереброваскулярные заболевания сопровождаются уменьшением мозгового кровотока. Недостаточное кровоснабжение мозга вызывает гибель нейронов и, как следствие, неврологический дефицит, а также нарушение ряда когнитивных функций. Известно, что нейротрофины (семейство полипептидных факторов роста) играют ключевую роль в развитии и функционировании нервной системы и способствуют выживаемости нейронов при различных патологиях. Однако использование нейротрофинов в «протективной» терапии ограничено из-за их неспособности проникать через ГЭБ. В этой связи много внимания уделяется синтезу низкомолекулярных пептидомиметиков нейротрофинов. Мы исследовали влияние синтетического низкомолекулярного аналога фактора роста нервов (NGF) ГК-2 на поведенческие и биохимические изменения у крыс, подвергнутых неполной глобальной ишемии. В первый день эксперимента животные получили инъекцию ГК-2 (1 мг/кг, в/бр), а через 24 ч им была проведена операция по двусторонней перевязке сонных артерий. Последующие инъекции ГК-2 животные получили на 3, 7 и 11 день эксперимента. Поведенческие изменения, вызванные ишемией, были оценены в тестах «Открытое поле» (день 8), «Исследование новых объектов» (день 9), «Экстраполяционное избавление» (день 10). Животных забивали декапитацией еще через 5 дней после последней инъекции препарата (день 16), мозг вынимали и проводили исследование жизнеспособности клеток коры, гиппокампа и стриатума с помощью МТТ-теста. Двусторонняя перевязка сонных артерий существенно повлияла на поведение животных. У них, по сравнению с ложнооперированными, значительно снизилась горизонтальная двигательная активность на периферии «открытого поля». Также уменьшилось число стоек с опорой на стенку поля (изменился компонент вертикальной двигательной активности). Кроме того, в тесте «Исследование объектов» у оперированных животных наблюдалось снижение исследовательского поведения. Все вышеперечисленные изменения были наиболее выражены в первую минуту тестирования. Вместе с тем, перевязка сонных артерий не нарушила поведения животных в тесте «Экстраполяционное избавление», что может быть обусловлено включением резервных путей кровоснабжения мозга в «стрессорных» условиях данного теста. Исследуемые показатели у оперированных крыс, получивших инъекции ГК-2, приближались к показателям ложноооперированных животных. Эти данные согласуются с результатами биохимических исследований, показавших положительное влияние ГК-2 на выживаемость клеток коры головного мозга крыс, подвергнутых операции. В целом, полученные данные указывают на возможность применения ГК-2 при ишемических состояниях. Работа выполнена по гранту РФФИ № 06-04-48683.