Anxiolytic Action of Dipeptide Mimetic of the BDNF Loop 2 in Adult Animals.

We studied the anti-anxiety effect of a low-molecular-weight mimetic of the BDNF loop 2, hexamethylenediamide bis-(-N-hexanoyl-L-seryl-L-lysine) (GTS-201) in adult animals. GTS-201 at a dose of 5 mg/kg after acute intraperitoneal administration to outbred male and female rats increased the time spent in the open arms and the number of entries into the open arms in the elevated plus maze (EPM). In "highly emotional" male BALB/c mice, GTS-201 exhibited a dose-dependent anxiolytic effect in the EPM in a dose range of 0.5-2.0 mg/kg with a maximum effective dose of 1 mg/kg. These data confirm the previously revealed anti-anxiety properties of GTS-201 in inbred male and female BALB/c mice and rats and indicate the dependence of the pharmacological activity of the BDNF mimetic on animal age.

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.

Selank, a Peptide Analog of Tuftsin, Attenuates Aversive Signs of Morphine Withdrawal in Rats.

Activity of a peptide tuftsin analogue Selank was studied in outbred rats using the naloxone-precipitated morphine withdrawal model. Single intraperitoneal injection of Selank in an anxiolytic dose of 0.3 mg/kg reduced the total index of morphine withdrawal syndrome by 39.6%, significantly (р<0.0001) attenuated convulsive reactions, ptosis, and posture disorders, and 9-fold increased the tactile sensitivity threshold in morphine-dependent rats in comparison with the group of active control; at the same time, Selank was slightly inferior to diazepam in a dose of 2 mg/kg by pharmacological activity (the decrease in total index of morphine withdrawal syndrome by 49.3% and 13-fold increase in sensitivity threshold). Thus, Selank, like diazepam, weakens the aversive signs of morphine withdrawal in rats with opiate dependence.

Low-Molecular-Weight Mimetic of BDNF Loop 2 Reduces Ethanol Consumption in Female Rats.

The study examined the effect of GTS-201, a low-molecular weight mimetic of brain-derived neurotrophic factor (BDNF) loop 2, on persistent alcohol craving in outbred male and female albino rats with ethanol preference score ~50% developed in the free choice paradigm between 10% ethanol and water over 24 weeks. Both single and subchronic (5 days) injections of GTS-201 in a daily dose of 5 µg/kg reduced alcohol deprivation effect in female, but not in male rats. The possibility of in vivo sex-dependent regulation of modeled alcohol craving with a low-molecular-weight dipeptide mimetic of BDNF loop 2 was demonstrated and sex-related differences in this effect were revealed.

Experimental Evaluation of Anxiolytic and Analgesic Properties of a New Linear Methoxyphenyltriazaalkane Derivative with Cardiotropic Activity.

The anxiolytic and analgesic properties of compound ALM-802, a cardiotropic linear methoxyphenyltriazaalkane derivative, combining pharmacophore elements of p-FOX inhibitors trimetazidine and ranolazine were studied in vivo. In the elevated plus-maze test, ALM-802 after acute intraperitoneal administration in doses of 1-8 mg/kg dose-dependently prevented the development of anxiety in BALB/c mice. Chronic intraperitoneal administration of ALM-802 in a dose of 2 mg/kg to alcohol-preferring rats attenuated anxiogenesis induced by ethanol withdrawal. ALM-802 demonstrated antinociceptive activity in C57BL/6 mice during thermal stimulation of nociceptors in the hot plate test and during modeling of visceral pain in the acetic acid writhing test. Thus, ALM-802 exhibits anxiolytic and analgesic properties in the dose range corresponding to its anti-ischemic and antiarrhythmic effects.

Peptide Mimetic of BDNF Loop 4 Blocks Behavioral Signs of Morphine Withdrawal Syndrome and Prevents the Increase in ΔFosB Level in the Striatum of Rats.

Activity of compound GSB-106, a low-molecular mimetic of loop 4 of the brain neurotrophic factor (BDNF), was studied in experimental morphine withdrawal syndrome simulated in outbred rats. Single and subchronic (5 intraperitoneal injections) administration of GSB-106 in a dose of 0.1 mg/kg significantly reduced the total index of morphine withdrawal syndrome by 55.2 and 45.6%, respectively. GSB-106 reduced the severity of some behavioral signs (piloerection, gnashing of teeth, wet-dog shaking, and runaway attempts), but had no effect on mechanical allodynia formed in the rats with dependence. Subchronic treatment with GSB-106 prevented the increase in the content of ΔFosB (product of early response gene) in the striatum induced by morphine withdrawal. The results confirmed the concept on the involvement of neurotrophins, specifically BDNF and its analogs, in the mechanisms associated with the formation of opiate dependence.

Comparative Assessment of the Effectiveness of Noncompetitive NMDA Receptor Antagonists Amantadine and Hemantane in Morphine Withdrawal Syndrome Model.

Activities of noncompetitive NMDA receptor antagonists (aminoadamantane derivatives) were assessed in random-bred rats with modeled morphine withdrawal syndrome. A single intraperitoneal injection of hemantane (10 or 20 mg/kg) significantly and dose-dependently moderated some behavioral symptoms (teeth-chattering, ptosis, and vocalization) and reduced total score of morphine withdrawal syndrome. In morphine-abstinent rats, hemantane partially prevented the decrease in the thresholds of tactile sensitivity, but had no effect on locomotor activity and body weight loss. Under conditions of morphine withdrawal, intraperitoneal injection of amantadine (10 or 20 mg/kg) decreased motor activity and promoted body weight loss in parallel with the development of mechanical allodynia, but had no effect on the total withdrawal score. Comparison of aminoadamantane derivatives by behavioral and physiological parameters demonstrated the advantage of hemantane during morphine abstinence indicating the need of its study as a promising anti-addiction remedy.

Selank, Peptide Analogue of Tuftsin, Protects Against Ethanol-Induced Memory Impairment by Regulating of BDNF Content in the Hippocampus and Prefrontal Cortex in Rats.

The effects of a peptide anxiolytic Selank synthesized on the basis of the endogenous peptide tuftsin on memory impairment and content of brain-derived neurotrophic factor (BDNF) in brain structures were analyzed in outbred rats receiving 10% ethanol as the only source of fluid for 30 weeks. In the object recognition test, Selank (0.3 mg/kg a day, 7 days, intraperitoneally) produced a cognitive-stimulating effect in 9 months rats not exposed to ethanol (p<0.05) and prevented the formation of ethanol-induced memory and attention disturbances (p<0.01) developing during alcohol withdrawal. In ex vivo experiments, Selank prevented ethanol-induced increase in BDNF content in the hippocampus and frontal cortex (p<0.05). These results indicate positive effects of the tuftsin analogue on age-related memory disturbances associated with chronic alcohol intoxication and confirm the involvement of the neurotrophin mechanism related to BDNF production into the effect of Selank.

Formation of Alcohol Motivation in Monkeys (Macaca mulatta) Kept in Isolation.

The effects of environmental factors (flavors, different ethanol concentration, alcoholic deprivation, and food reinforcement) on the formation of alcohol motivation was studied in rhesus macaques (Macaca mulatta, n=6). Motivation for alcohol intake was induced in two stages: initiation (sessions 1-160) and formation of motivation (sessions 161-516). Monkeys preferred multifruit flavor and 4% ethanol solution, while ethanol deprivation did not stimulate alcohol consumption. The pronounced individual differences in the pattern of alcohol motivation were revealed: the intake of 4% ethanol solution ranged from 0.21±0.03 to 0.43±0.06 g/kg without food reinforcement and increased from 0.78±0.03 to 1.22±0.09 g/kg with food reinforcement. The results suggest that the proposed method is valid and can be used as an experimental model of alcohol dependence in non-human primates.

Dipeptide Mimetic of the BDNF Loop 4 Possesses Analgetic Activity.

Previously, we synthesized a dimeric dipeptide mimetic of the brain-derived neurotrophic factor (BDNF) loop 4, GSB-106, which, similarly to BDNF, activated TrkB, PI3K/AKT, and MAPK/ERK. When administered systemically, it exhibited neuroprotective, antidepressant, and antidiabetic activities and stimulated neurogenesis and synaptogenesis. In this study, we established that GSB-106 also exhibits the analgesic activity, typical for BDNF, which was revealed in rats in hot plate and tail flick tests 0.5-48 h after intraperitoneal injection at doses of 0.1 and 1 mg/kg.

Specific Features of Depolarization of the Left and Right Atria in Rats with Alcoholic Cardiomyopathy.

Using a translation model of alcoholic cardiomyopathy in rats we showed the presence of an additional abnormal excitation focus in the area of the pulmonary vein lacunae in the left atrium and enhanced heterogeneity of the atrium depolarization pattern. These changes can determine electric instability of the myocardium and induce malignant heart rhythm disturbances including, sudden cardiac death.

Epac Proteins and Calmodulin as Possible Arrhythmogenesis Trigger in Alcoholic Cardiomyopathy.

The expression of Epac proteins (exchange protein directly activated by cAMP) and calmodulin (CaM) was assessed by the content of the corresponding mRNA in biopsy specimens of cardiac atrium, left ventricle, and thoracic aorta of rats with alcoholic cardiomyopathy. In the myocardium, overexpression of Еpac1, Ерас2, and СаМ mRNA was found. The content of Epac2 mRNA in the left ventricle was elevated by 2.9 times (p=0.000001), in the left atrium by 3.2 times (p=0.00001), in the right atrium by 3 times (p=0.00001). In contrast to the myocardial tissue, the content of CaM mRNA in the thoracic aorta was not increased, but showed a tendency to decrease, when compared to the control values, while the level of Epac1 and Epac2 mRNA was increased. The assumption is made that regulatory proteins Epac and CaM can play a key role in arrhythmogenesis development under conditions of alcoholic cardiomyopathy.

Atria Depolarization in Rats with Alcoholic Cardiomyopathy.

Chronotopography of atrial subepicardium depolarization has been studied in a rat model of alcoholic cardiomyopathy. Formation of independent sources of initial atrial activity has been detected in the right and left atria. These sources induced the formation of several depolarization fronts that propagated autonomously, and this can be regarded as the cause of atrial arrhythmia.

Non-Competitive NMDA Receptor Antagonist Hemantane Reduces Ethanol Consumption in Long-Term Alcohol Experienced Rats.

Activity of hemantane, an amino adamantane derivative, exhibiting the properties of lowaffinity non-competitive NMDA receptor antagonist, was evaluated in experimental in vivo models of alcoholism. Hemantane had no effects on the formation and manifestation of behavioral sensitization to ethanol in DBA/2 mice. Under conditions of free choice between 10% ethanol and water, hemantane (20 mg/kg/day for 14 days, intraperitoneally) significantly reduced the daily ethanol intake in random-bred male rats with formed alcohol motivation (>4 g/kg of ethanol). During modelling of withdrawal syndrome, hemantane administered intraperitoneally in doses of 5-20 mg/kg dose-dependently attenuated alcohol-deprivation effect after acute withdrawal with no effects on protracted abstinence. It was found that hemantane suppressed alcohol drinking behavior in long-term ethanol experienced rats and attenuated alcohol-seeking behavior after acute withdrawal.

Anxiolytic Properties of Trimetazidine in Experimental Models of Increased Anxiety.

Effect of trimetazidine (20 and 30 mg/kg) on elevated plus maze behavior of rodents was assessed in the genetic and pharmacological anxiety models. Single intraperitoneal injection of trimetazidine in a dose of 20 mg/kg prevented anxiety development in highly emotional male BALB/c mice and increased the time spent in open arms of the maze. In outbred male rats receiving 10% ethanol solution for 20 weeks, trimetazidine administered intraperitoneally in a dose of 20 mg/kg for 28 days abolished ethanol withdrawal-induced anxiogenesis developed against the background of 4-week alcohol deprivation: it increased the time spent in open arms, the number of entries into open arms, and total locomotor activity in the maze. Anxiolytic properties of trimetazidine were not inferior to those of the non-benzodiazepine anxiolytic Afobazole (fabomotizole) in acute and chronic administration.

Alcoholic Cardiomyopathy: Translation Model.

We developed a translation model of alcoholic cardiomyopathy in rats. By the end of forced alcoholization (the rats received 10% ethanol solution as the only source of fluid for 24 weeks; mean daily ethanol consumption was 5.0-6.5 g/kg), the rats developed dilated heart failure. Echocardiography and morphometric study of the myocardium revealed a decrease in inotropic function of the heart and dilatation of the right and left ventricles. Fatty degeneration of the myocardium (pathognomonic sign of alcoholic cardiomyopathy) and decrease in electrical stability of cardiomyocytes reliably reproduce the clinical pattern of alcoholic cardiomyopathy.

Selank Inhibits Ethanol-Induced Hyperlocomotion and Manifestation of Behavioral Sensitization in DBA/2 Mice.

The effect of non-benzodiazepine anxiolytics on the ethanol-induced hyperlocomotion and behavioral sensitization was assessed in male DBA/2 mice. Selank that enhances activity of the endogenous opioid system (0.3 mg/kg, intraperitoneally), similar to the nonselective opiate receptor blocker naloxone (1.0 mg/kg, intraperitoneally), prevented the development of ethanol-induced (2.0 g/kg intraperitoneally) hyperlocomotion, in contrast to σ1-receptors agonist Afobazole (1.0 mg/kg, intraperitoneally) that did not inhibit ethanol-induced behavioral stimulation. Single dose of Selank significantly blocked manifestation of motor sensitization without affecting its formation. These findings suggest that Selank can modulate the motivational effects of ethanol.

Pharmacological Correction of Alcohol Motivation Depends on the Phenotype of the Response to Emotional Stress.

The specific features of alcohol behavior were studied in MR and MNRA rats that exhibit an opposite reaction to emotional stress. We evaluated the effect of a dipeptide anxiolytic GB-115 (N-phenyl-hexanoyl-glycyl-L-tryptophan amide, neuropeptide cholecystokinin-4 analogue with antagonistic activity) on alcohol motivation in rats, which was formed over 12 months. High-emotionality MR rats were more sensitive to the anxiolytic effect of ethanol in the conflict situation test than low-emotionality MNRA rats. MNRA rats consumed a greater amount of ethanol under a free-choice condition with 15% ethanol solution and water (as in comparison with MR rats). However, the behavior of MR rats was transformed due to a significant increase in alcohol motivation from the 5th month of long-term free access to ethanol. An anxiolytic GB-115 (0.025 mg/kg intraperitoneally for 14 days) with selective activity in high-emotionality rats was shown to reduce significantly the average daily consumption and alcohol-deprivation effect in MR rats, but did not modulate ethanol addiction in MNRA rats.

Evidence of Echocardiography Validity in Model Experiments on Small Animals.

Dynamic echocardiographic monitoring in rats subjected to forced alcoholization showed the formation of disorders in intracardiac hemodynamics characteristic of ethanol cardiomyopathy formed by the end of 24-week continuous ethanol consumption. The results of echocardiographic monitoring were confirmed by histological and morphometric studies demonstrating fatty infiltration of the myocardium pathognomonic for this condition and bifocal dilatation of cardiac ventricles. These results persuasively demonstrate that echocardiographic studies on small animals are valid and can be used for search for cardiotropic drugs and studies of the mechanisms of their activities.

PECULIARITIES OF THE EFFECT OF AMINOADAMANTANE DERIVATIVES ON ETHANOL-INDUCED ATAXIA. SEDATION. AND HYPERLOCOMOTION IN MICE.

The influence of two aminoadamantane derivatives representing low-affinity NMDA receptor antagonists, which show antiparkinsonian-like activity both in animal models and in patients with Parkinson's disease, have been studied in vivo on mice with acute ethanol-induced disorders. N-(adamant-2-yl) hexamethyleneimine hydrochloride (himantane) in doses of 5--20 mg/kg, i.p., dose-dependently prevented ethanol-induced ataxia in CD-I mice, sedation in C57BI/6 mice, and hyperlocomotion in DBA/2 mice. At the same time, I -aminoadamantane (amantadine) in doses of 10 - 20 mg/kg, i.p., did not attenuate acute ethanol-induced (2 g/kg, i.p.) effects. Neither himantane nor amantadine influenced the duration of ethanol narcosis (5.5 g/kg, i.p.) in CD-I mice. The obtained data showed a difference of the pharmacodynamic profile of himantane as low-affinity NMDA receptor antagonist in interaction with ethanol at doses inducing behavioral disorders.