Chronic Ethanol Consumption by Rats before Mating Affects Working Memory in the Offspring

Parameters of non-spatial and spatial memory were evaluated in sexually mature offspring of outbred rats (females and males F0) consuming a 10% ethanol solution for 30 weeks before mating. We found a significant increase in the recognition index in F1 males and its decrease in F1 females in the novel object recognition test. During the first days of the experiment in T-maze, a decrease in spatial memory was revealed in F1 males, which remained at the trend level until the end of testing; no significant deviations were detected in F1 females. Memory impairment in F1 females was accompanied by a decrease in BDNF level in the hippocampus, but not in the prefrontal cortex. Thus, ethanol consumption by F0 rats before mating led to impairment of long-term working memory only in female F1 offspring.

Pharmacogenetic Analysis of the Interaction of the Low-Molecular-Weight BDNF Mimetic Dipeptide GSB-106 with TRK Receptors

Using TrkA or TrkB receptor gene knockout HT-22 cells, the selectivity of the interaction of the low-molecular-weight dipeptide BDNF mimetic GSB-106 (hexamethylenediamide bis(N-monosuccinyl-L-seryl-L-lysine)) with TrkB receptors was shown.

Сhronically Administered BDNF Dipeptide Mimetic GSB-106 Prevents the Depressive-like Behavior and Memory Impairments after Transient Middle Cerebral Artery Occlusion in Rats

BACKGROUND

A dipeptide mimetic of the BDNF loop 4, bis (N-monosuccinyl-L-seryl-L-lysine) hexamethylenediamide, GSB-106, was designed and synthesized by V.V. Zakusov Research Institute of Pharmacology. The compound activated in vitro TrkB, MAPK/ERK, PI3K/AKT, and PLCγ, like full-length BDNF. In vivo, GSB-106 exhibited antidepressant-like, neuroprotective and neuroregenerative properties. The aim of this work was to study the effects of GSB-106 on depressive-like behavior, cognitive impairments, as well as on hippocampal neuroplasticity in an experimental model of ischemic stroke.

METHODS

Male Wistar rats were subjected to 60 minutes of transient middle cerebral artery occlusion (MCAO). Dipeptide GSB-106 was administered intraperitoneally at a dose of 0.1 mg/kg/day for 21 days after surgery. 30-40 days after MCAO, the depressive-like state in the forced swimming test and memory impairment in the novel object recognition test were assessed. Then, the content of CREB, as a neuroplasticity marker, was assessed in the ipsilateral hippocampus.

RESULTS

Rats in MCAO group showed depression-like behavior (increase in immobility time in the forced swimming test by 22% compared to sham group), impairments in short-term and long-term memory (decrease in the discrimination index in the novel object recognition test by 70% and 50%, respectively), and a decrease in immunoreactivity to CREB (cAMP response element-binding protein) in the hippocampus by 36% as compared with the sham group. GSB-106 completely prevented the behavior impairments and counteracted the reduction of immunoreactivity to CREB in the hippocampus.

CONCLUSION

The BDNF dipeptide mimetic GSB-106 is promising for further development as a drug for the treatment of poststroke neuropsychiatric disorders.

Neuroprotective Properties of Quinone Reductase 2 Inhibitor M-11, a 2-Mercaptobenzimidazole Derivative

The ability of NQO2 to increase the production of free radicals under enhanced generation of quinone derivatives of catecholamines is considered to be a component of neurodegenerative disease pathogenesis. The present study aimed to investigate the neuroprotective mechanisms of original NQO2 inhibitor M-11 (2-[2-(3-oxomorpholin-4-il)-ethylthio]-5-ethoxybenzimidazole hydrochloride) in a cellular damage model using NQO2 endogenous substrate adrenochrome (125 µM) and co-substrate BNAH (100 µM). The effects of M-11 (10-100 µM) on the reactive oxygen species (ROS) generation, apoptosis and lesion of nuclear DNA were evaluated using flow cytometry and single-cell gel electrophoresis assay (comet assay). Results were compared with S29434, the reference inhibitor of NQO2. It was found that treatment of HT-22 cells with M-11 results in a decline of ROS production triggered by incubation of cells with NQO2 substrate and co-substrate. Pre-incubation of HT-22 cells with compounds M-11 or S29434 results in a decrease of DNA damage and late apoptotic cell percentage reduction. The obtained results provide a rationale for further development of the M-11 compound as a potential neuroprotective agent.

Neuroregenerative activity of the dipeptide mimetic of Brain Derived Neurotrophic Factor GSB-106 under experimental ischemic stroke

BACKGROUND

A dimeric dipeptide mimetic of the BDNF loop 4, bis(N-monosuccinyl-L-seryl-L-lysine) hexamethylenediamide (GSB-106), which activates TrkB, PI3K/AKT, MAPK/ERK and PLC-γ1 was created at the V.V. Zakusov Research Institute of Pharmacology. GSB-106 showed neuroprotective activity in vitro and in vivo at systemic administration.

OBJECTIVE

In this work, we studied the GSB-106 effect on the cerebral infarct volume, as well as on neurogenesis and synaptogenesis under experimental ischemic stroke, induced by intravascular occlusion of the middle cerebral artery in rats.

METHODS

GSB-106 was administered i.p. in a dose of 0.1 mg/kg 24 h after surgery and then once a day, with the end of administration on the day 6 after surgery. On the day 7 brain samples were collected for morphometric and biochemical (Western-blot) analysis.

RESULTS

It was established that GSB-106 reduced the brain damage volume by 24%, restores impaired neurogenesis and/or gliogenesis (by Ki-67) in the hippocampus and in the striatum and completely restored the reduced immunoreactivity to synaptic markers synaptophysin and PSD-95 in the striatum.

CONCLUSIONS

Thus, the dimer dipeptide BDNF mimetic GSB-106 exhibits neuroregenerative properties at clinically relevant time window (24 h) in a model of ischemic stroke presumably due to stimulation of neurogenesis (and/or gliogenesis) and synaptogenesis.

Low-Molecular Weight BDNF Mimetic, Dimeric Dipeptide GSB-106, Reverses Depressive Symptoms in Mouse Chronic Social Defeat Stress

A mimetic of the BDNF loop 4, bis (N-monosuccinyl-L-seryl-L-lysine) hexamethylenediamide, named GSB-106, was designed and synthesized in our scientific group. The compound activated TrkB, MAPK/ERK, PI3K/AKT, and PLCγ in in vitro experiments. In vivo experiments with rodents revealed its antidepressant-like activity in the forced swim and the tail suspension tests at the dose range of 0.1–5.0 mg/kg (i.p., p.o.). However, GSB-106 was not studied in depression models modulating major depression in humans. In the present study, the GSB-106 antidepressant-like activity was revealed in mice at the depression model induced by 28-day social defeat stress with 21-days oral administration (0.1 mg/kg) after stress. At the same time, GSB-106 restored reduced locomotor activity and completely eliminated the anhedonia manifestations. The compound also restored reduced levels of synaptophysin and CREB in the hippocampus. In addition, the Trk receptor antagonist K252A, and the PLC inhibitor U73122, were found to completely block the antidepressant-like activity of GSB-106 in the forced swimming test in mice. Thus, the present results demonstrate the dipeptide BDNF mimetic GSB-106 reversed depressive-like behavior and restored hippocampal neuroplasticity in a rodent depression model. These effects of GSB-106 are probably regulated by TrkB signaling.

Dipeptide Mimetics of Different NGF and BDNF Loops Activate PLC-γ1

Previously, we designed and synthesized dipeptide mimetics of individual loops of the nerve growth factor (NGF) and the brain-derived neurotrophic factor (BDNF). It was shown that these mimetics activate the corresponding tyrosine kinase (Trk) receptors and have different patterns of activation of the PI3K/AKT and MAPK/ERK postreceptor signaling pathways in vitro. In the present study, it was shown on HT-22 cells that all these compounds activate the phospholipase C-γ1 (PLC-γ1) cascade.

Mimetics of brain-derived neurotrophic factor loops 1 and 4 are active in a model of ischemic stroke in rats

BACKGROUND

Two dimeric dipeptides, bis-(N-monosuccinyl-l-seryl-l-lysine)hexamethylenediamide (GSB-106) and bis-(N-monosuccinyl-l-methionyl-l-serine) heptamethylenediamide (GSB-214), were designed based on the brain-derived neurotrophic factor (BDNF) loop 4 and loop 1 β-turn sequences, respectively. Earlier, both of these dipeptides were shown to exhibit neuroprotective activity in vitro (10-5-10-8 M). The present study aimed to investigate the mechanisms of action of these peptides and their neuroprotective activity in an experimental stroke model.

METHODS

We used western blot and HT-22 hippocampal neuronal cell line to investigate whether these peptides induced phosphorylation of the TrkB receptor and the AKT and ERK kinases. Rat middle cerebral artery occlusion (MCAO) was used as a stroke model. GSB-106 and GSB-214 were administered intraperitoneally (0.1 mg (1.3×10-7 mol)/kg) 4 hours after MCAO and daily for 7 days. The cerebral infarct volumes were measured with 2,3,5-triphenyltetrazolium chloride staining 21 days after MCAO.

RESULTS

Both compounds were shown to elevate the TrkB phosphorylation level while having different post-receptor signaling patterns. GSB-106 activated the PI3K/AKT and MAPK/ERK pathways simultaneously, whereas GSB-214 activated the PI3K/AKT only. In experimental stroke, the reduction of cerebral infarct volume by GSB-106 (∼66%) was significantly greater than that of GSB-214 (∼28% reduction), which could be explained by the fundamental role of the MAPK/ERK pathway in neurogenesis and neuroplasticity. Notably, between these two dipeptides, only GSB-106 exhibited antidepressant activity, as was found previously.

CONCLUSION

The results provided support for the beneficial pharmacological properties of BDNF loop 4 mimetic GSB-106, thereby suggesting a potential role for this dipeptide as a therapeutic agent.

[COMPARISON OF CYTOPROTECTIVE EFFECTS OF HEMANTANE AND AMANTADINE UNDER CONDITIONS OF 6-HYDROXYDOPAMINE NEUROTOXIN ACTION ON CULTURED HUMAN NEUROBLASTOMA CELLS]

Potential neuroprotective activity of the novel antiparkinsonian drug hemantane (hydrochloride N-2-(adamantyl)-hexamethylenimine) in comparison to amantadine has been studied in various regimes of administration on human neuroblastoma SH-SY5Y cell line injury induced by 6-hydroxydopamine (6-OHDA), which is used as in vitro model of dopaminergic neurons for Parkinson's disease. Two regimes of hemantane and amantadine administration in a range of final concentrations 10⁻⁶-10⁻⁸ M were used either prior to or immediately after 6-OHDA introduction. MTT colorimetric assay was used to assess the viability of test cells. Significant decrease in viability of SH-SY5Y cells treated with 6-OHDA was observed. The addition of hemantane to cell medium produced cytoprotective effects in both regimes of administration--before and after 6-OHDA--at concentrations 10⁻⁷ M and 10⁻⁶-10⁻⁸ M, respectively. Amantadine in con- centrations 10⁻⁷-10⁻⁸ M was effective to increase cell survival only when administered after 6-OHDA. These results show that hemantane has a greater neu-roprotective potential in comparison to amantadine.

[Study of structure-activity relationship in series of Gsb-106 analogues-dipeptide mimetics of brain-derived neurotrophic factor]

In previous work we have obtained a dimeric dipeptide mimetic of 4th loop of BDNF - hexamethylenediamide bis-(N-monosuccinil-L-seryl-L-lysine) (GSB-106), having a neuroprotective activity in vitro in a concentration range 10(-5)-10(-8) M and an antidepressant activity in vivo at doses 0.1 and 1 mg/kg i.p. in rats. We have investigated the structural and functional relationships among analogues of GSB-106. Glycine scan was performed and a number of appropriate compounds were synthesized: GT-105 (here lysine is replaced by glycine), GT-107 (here serine is replaced by glycine), GT-106Ac (here monosuccinic radical is replaced by acetyl group). We have studied the dependence of activity of following compounds from the configuration of amino acid residues: GT-107D (D-enantiomer of the GT-107), GT-106DL (L-serine was replaced by D-serine), GT-106LD (L-lysine was replaced by D-lysine). The investigation of these compounds using the HT22 cell culture in conditions of oxidative stress has approved only two analogues of GSB-106 to have a neuroprotective effect: in the case of replacement of serine to glycine and of replacment of succinic radical to acetic group. A disappearance of this effect was observed in event of the replacement of lysine residue to glycine in GT-105, L-lysine residue to D-lysine and also by conversion of serine configuration. These results show that lysine residue is crucial for the neuroprotective activity of GSB-106. L-Configuration of the lysine and serine residues required. Configuration of lysine residue becomes critical in absence of serine side group. Thus, the the following fragment is a minimum pharmacophore of beta-turn of 4 loop of BDNF: HOOC-CH2-CH-CO-NH-(S)-CH(CH2OH)-CO-NH-(S)-CH((CH2)4NHz)-CO-NH-(CH2)3-. Only one (GT-106Ac) out of two analogues of GSB-106 with neuroprotective activity possesses antidepressant activity too. This fact indicates about a necessity of more stringent structural requirements for exposure of antidepressant activity. The results obtained can be useful for designing of new active mimetics of BDNE

[Neuroprotective effect of neuroglutam under conditions of activated free radical oxidation]

The neuroprotective properties of the novel glutamic acid derivative neiroglutam have been studied in vitro and in vivo. Neiroglutam demonstrated the protective action on 6-OH-dopamine neurotoxicity model <MI> in vitro, where free radical oxidation is a basic part of pathogenesis. In control rats, focal brain ischemia caused significant increase in thiobarbituric acid reactive species (TBARS) level and decrease in superoxide dismutase (SOD) enzyme activity. In two-year-old rats, preventive administration of the neiroglutam caused a significant reduction in the TBARS plasma concentration (34.5%, p < 0.05), increased SOD activity, and increased the time of acid-induced hemolysis of erythrocytes (40%, p < 0.05).

[Design and synthesis of dipeptide mimetics of brain-derived neurotrophic factor]

Low-molecular mimetics of brain-derived neurotrophic factor (BDNF) loops 1 and 4 representing to monomeric and dimeric amides of N-acyldipeptides were constructed and synthesized. The sequence of these dipeptides coinside with the central regions of beta-turns of corresponding loops of neurotrophine sequence, and acyl groups are bioisosters of preceding amino acid residues. Hexa- and heptamethylenediamine were used as spacers linking C-terminus ofdipeptides in BDNF dimeric mimetics. These substances were synthesized by classic peptide synthesis methods in solution and got laboratory codes GSB-104 (HO-Suc-Ser-Lys-NH2), GSB-106 ([HO-Suc-Ser-Lys-NH-(CH2)3-]2), GSB-207 (HO-Suc-Met-Ser-NH2) and GSB-214 ([HO-Suc-Met-Ser-NH-(CH2)7/2-]2). By using the culture of immortalized hippocampal cell line HT-22 on the oxidative stress conditions it was shown that dimeric mimetics of both loops demonstrated neuroprotective activity in the concentration rage of 10(-5)-10(-8) M. Monomeric loop 1 mimetic GSB-207 was inactive in the same concentrations and monomeric loop 4 mimetic GSB-104 in a concentration of 10(-7) M decreased survival of neurons. Presence of neuroprotective activity only for dimeric mimetics correlates with the data that BDNF is active only in homodimeric form. As opposed to dimeric mimetic of loop 1 GSB-214, dimeric mimetic of loop 4 GSB-106 demonstrates specific for BDNF antidepressive activity in Porsolt test on rats in doses 0.1 and 1 mg/kg i.p. It is suggested that antidepressive activity of BDNF is associated with its loop 4. We consider that compounds obtained will be useful for investigation of BDNF action mechanism and can lead to creation of a new group of medicinal substances with antidepressive and neuroprotective activities.

[A comparative study of hemantane and amantadine effects on dopamine transporter expression in brain of normal and MPTP-treated C57BL/6 mice]

The effects of acute and subchronic administration of antiparkinsonian drugs hemantane and amantadine on dopamine transporter (DAT) content in the brain of normal and MPTP-treated mice have been studied. MPTP treatment (30 mg/kg, daily for 2 days, i.p.) led to an insignificant decrease of the DAT level in striatum, while not influencing the DAT content in the frontal cortex of mice. The acute administration of hemantane (20 mg/kg, i.p.) failed to influence the DAT levels in the tested structures of mice brain, while amantadine (13.9 mg/kg, i.p) decreased the DAT level but only in striatum. The acute administration of a drug (hemantane or amantadine) simultaneously with MPTP toxin reduced the DAT levels in striatum but did change the DAT concentration in the frontal cortex. On the contrary, the subchronic injection of hemantane alone (7 x 20 mg/kg, i.p.) and in combination with the toxin increased the DAT levels in the brain structures, while amantadine (7 x 13.9 mg/kg, i.p.) led to a pronounced increase of DAT concentration only in the striatum. Thus, both similar and dissimilar trends in the neurochemical effects of hemantane and amantadine have been experimentally revealed.

[Effects of afobazole on the stress protein HSP70 level in the brain tissue of rats with global transient ischemia]

Experiments in anesthetized rats showed that global transient brain ischemia caused a significant decrease in cerebral blood flow in rat cerebral cortex and reduced the stress protein HSP70 level in striatum. Afobazole administration restored the cerebral blood supply disturbed by ischemia and increased the stress protein HSP70 synthesis in striatum.