The experimental study is devoted to the identification of possible psychomodulatory and anxiolytic effects of ACTH(4- 7)-Pro-Gly-Pro and ACTH(6-9)-Pro-Gly-Pro under conditions of thyroid hyperfunction. Material and methods. The experiment was performed on white male rats, which were divided into groups: I – control; II – rats with hyperthyroidism model, III and IV – animals receiving ACTH(4-7)-Pro-Gly-Pro (Semax) and ACTH(6-9)-Pro-Gly-Pro at doses of 174 and 178 μg/kg/day, respectively, for 21 days against the background of hyperthyroidism. The development of experimental hyperthyroidism in animals was induced by administration of an aqueous solution of potassium iodide at a dose of 75 µg/kg by intragastric gavage, daily for 3 weeks. Behavioural activity was assessed using psychopharmacological tests “Lattice” and “Light-Dark box” in standard modification. Results and discussion. Under conditions of experimental hyperthyroidism in the “Lattice” test, changes in psychomotor behaviour of animals were observed in the form of suppression of orienteering and exploratory activity, namely, a decrease in the number of stands and exploratory “peeks” downwards. In the test “Light-Dark box” against the background of thyroid hyperfunction, an increase in the level of anxiety was observed, manifested in a decrease in the time spent in the light compartment, the number of transitions between compartments and racks, as well as an increase in the number of assessments of “risk” – “looking out” of the compartment. The studied substances ACTH(4-7)-Pro-Gly-Pro and ACTH(6-9)-Pro-Gly-Pro in conditions of experimental hyperthyroidism promoted the correction of the above-mentioned behavioural disorders, eliminating the anxiety-depressive state of laboratory animals. Conclusions. When studying the effect of ACTH(4-7)-Pro-Gly-Pro and ACTH(6-9)-Pro-Gly-Pro substances under conditions of experimental hyperthyroidism on behavioural activity of white rats in the tests “Lattice” and “Light-Dark box” it was revealed that the studied peptide compounds exhibit psychomodulatory and anxiolytic effects, correcting behavioural reactions.

The conditions for introducing deuterium into Trp-Pro-Pro-Trp and Boc-Trp-Pro-Pro-Trp by isotope exchange with D2O in the presence of a 5

ACTH/MSH-like peptides (melanocortins) have a wide range of neurotropic effects, including effects on learning and memory processes, neuroprotection, emotional state and pain sensitivity. Present work is aimed to compare the effects of peptides, the structure of which includes a natural fragment of ACTH and a stabilizing tripeptide PGP. The peptides ACTH4–7PGP (Semax), ACTH6–9PGP, and ACTH7–10PGP were used in the work. The effects of these peptides on the exploratory behavior, anxiety level and pain sensitivity of white rats, as well as on the protein levels of the neurotrophic factors BDNF (brain derived neurotrophic factor) and VEGF (vascular endothelial growth factor) in primary neuron cultures were studied. A comparative study of the effects of analogs of different ACTH/MSH fragments revealed both similarities and differences in their neurotropic activity. The peptides structure of which includes a sequence of ACTH4–7 or ACTH6–9 have nootropic, anxiolytic and analgesic activity, and also cause an increase in VEGF levels in the culture of hippocampal neurons. The peptide containing the ACTH7–10 sequence in the structure exhibits anxiolytic activity, increases exploratory behavior, does not affect pain sensitivity and has a stimulating effect on BDNF and VEGF levels in neuronal cultures. The data obtained indicate that different parts of the N-terminal region of the ACTH molecule are responsible for the manifestation of certain neurotropic effects of melanocortins. The results of the study can be used in the development of therapeutics based on natural melanocortins.

The efficiency of incorporating deuterium into 4-aminobutanoic acid (GABA) has been studied. The use of D2O at 200°C makes it possible to introduce into GABA an average of about 0.5 deuterium atoms, D2O with trifluoroacetic acid (1 : 1) at 250°C, an average 1.49 deuterium atoms with a yield of 15

Stress can disrupt bidirectional communication within the framework of the microbiota-gut-brain axis, including affecting the microbiological landscape and morphofunctional state of the mucous membrane of the colon. In this work we studied the ability of the peptide Thr-Lys-Pro-Arg-Pro-Gly-Pro (tuftsin-pgp) to correct the state of stress-induced dysbiosis in doses of 80, 250 and 750 pg/kg. The increase in the specific content, frequency of occurrence and relative average value of opportunistic bacteria of control stressed animals noted in the study with a decrease in the number and proportion of obligate bacteria indicated active colonization of the mucous membrane of the colon by them. Administration of tuftsin-pgp dose-dependently changed the qualitative and quantitative composition of the studied biotope microbiota. We found out that the most pronounced positive effect on the signs of stress-induced dysbiosis was the administration of the peptide at a dose of 250 pg/kg.

In modern physiology, the priority direction is the study of the influence of various types of stress, leading, as a rule, to the development of depressive states, on the physiological systems of the body. The main methods for assessing the neuroprotective effect, which is the main component of defense against stress, include the study of behavioral reactions that reflect motor, emotional, and cognitive changes. The study of drugs based on regulatory peptides is promising. Semax (ACTH4-7PGP) is a representative of a new synthetic peptide engineering, practically devoid of a hormonal effect and completely preserving the neurotropic activity of adrenocorticotropic hormone. The aim of the work was an experimental study of the effect of semax on the behavior of animals under the influence of experimental depression based on “social” stress. Material and methods. The study was carried out on 50 outbred male rats aged 6 months. Semax effects were studied under conditions of sensory contact - a model of experimental depression based on the formation of aggressive and submissive behavior in animals, using the multicomponent model the Suok test (“ropewalking”) and the Porsolt test to assess the depressive behavior of rats. Results and its discussion. Intermale confrontations led to a decrease in the time spent in the light half of the test, the number of “exploratory” downward glances, directional head movements; a decrease in the number of visited segments in the light section in victims and aggressors. As a whole, the study of behavioral reactions in animals in the Suok test and the Porsolt test in the model of experimental depression (sensory contact) showed the formation of an anxious-depressive state in animals, which was confirmed by a decrease in the motor and exploratory activity of rats. The results were obtained during the Porsolt test, indicating the formation of a depressive state in animals, which was confirmed by an increase in the total period of immobility in both aggressors and victims, an increase in the time of passive swimming, and a decrease in the time of active swimming. With a comprehensive assessment of animal behavior indicators in the Suok test, against the background of a decrease in the level of anxiety under the influence of semax, an improvement in the parameters of exploratory behavior was observed, in the Porsolt test – of motor activity indicators. Conclusions. Investigation of semax effect on the behavioral reactions of animals under conditions of sensory contact indicates that this drug exhibits an anxiolytic and antidepressant effect, eliminating pathological changes in the psycho-emotional status of animals.

Acute stress exposure triggers a cascade of neurochemical reactions, leading, specifically, to behavior changes and increased pain tolerance in humans and animals. ACTH/MSH-like peptides play an important role in regulating the organism’s response to stressful exposures. The aim of the present study was to assess the effects of the heptapeptide Semax, a synthetic ACTH4–10 analog, in various models of acute stress. The effect of intraperitoneal Semax administration at doses of 0.05 and 0.5 mg/kg on changes in behavior and pain sensitivity of Wistar rats was investigated in models of inescapable intermittent footshock stress and forced cold-water swim stress. To assess the involvement of the endogenous opioid system in the effects of stress, there was studied an impact of the preadministration with the opioid receptor antagonist Naloxone (1 mg/kg). The stressors used led to an increase in the pain threshold in the paw-pressure test, which indicates the development of stress-induced analgesia (SIA). In addition, rats exposed to stress showed decreased exploratory behavior and increased anxiety-like behavior in the hole board test. Both Semax and Naloxone attenuated SIA in the model of inescapable footshock stress, but did not affect pain threshold values in the model of forced cold-water swim stress. Both drugs did not affect rat behavior in the above models of acute stress. It can be concluded that Semax attenuates the opioid form of SIA, but does not affect behavior changes in rats exposed to acute stress.

Tetrapeptide KKRR, corresponding to the ACTH 15-18 sequence, is the shortest fragment with high-affinity binding with the ACTH receptor; it does not activate this receptor and prevents the whole hormone molecule from binding to it, and thus exhibits the properties of an ACTH receptor antagonist. The aim of the present work was to study the effects of peptide ACTH 15-18 (KKRR) and its analog ACTH 15-18 PGP on behavior in Wistar rats in normal conditions and after acute stress produced by inescapable electrical foot shock. The peptides studied here did not affect the anxiety levels in white rats in normal conditions. Prior administration of ACTH 15-18 (250 μg/kg) and its analog ACTH 15-18 PGP (50 and 250 μg/kg) decreased anxiety and corticosterone release in rats which had received a acute electrical foot shock stress. The extent and duration of the anti-stress effects of ACTH 15-18 PGP were significantly greater than the extent and duration of the effects of its natural prototype.

Aim of the study was to investigate the immunotropic activity of neuropeptide compound Pro-Gly-Pro-Val under “social” stress. Material and methods . The study was conducted on nonlinear male rats (6 months old) under conditions of “social” stress, modeled by formation of submissive and aggressive types of animal behavior under conditions of constant sensory contact. The rats were divided into groups: Control I, animals housed alone in a cage and receiving water for injection in an equivalent volume; Control II, groups of stressed animals with aggressive and submissive types of behavior; III groups of stressed rats to which Pro-Gly-Pro-Val at a dose of 100 μg/kg/day; IV groups of stressed rats to which imunofan (Arg-Asp-Lys-Val-Tyr-Arg) at an average therapeutic dose of 0.7 μg/kg/day were administered intraperitoneally. The immunotropic properties of the neuropeptide compounds were evaluated according to the following indices: delayed-type hypersensitivity reaction index, direct hemagglutination reaction antibody titer and leukocytic formula values. Results . Injection of the tested compound Pro-Gly-Pro-Val under study leads to correction of the immune changes occurring against the background of “social” stress, namely, to an increase in the delayed-type hypersensitivity reaction index and the level of anti-erythrocytic antibodies, to an enhancement in the total leukocyte count and a restoration of the percentage ratio between the form elements of the leukocytic formula. Obtained results correlate with the results of studying the immunotropic action of the comparison preparation immunofan under the conditions of “social” stress. Conclusions . The results of the study of the immunotropic action of the neuropeptide compound Pro-Gly-Pro-Val under “social” stress indicate the presence of its immunocorrective activity, which is manifested by the restoration of indices of cellular and humoral reactions and white blood cells.

Aim . To study the morphofunctional state of the colonic wall in rats when using the N–terminal analog of the adrenocorticotropic hormone (ACTH) ACTH6-9-Pro-Gly-Pro (ACTH 6-9 -PGP) peptide under chronic stress. Materials and methods . The study was performed on 55 male Wistar rats, which were divided into 5 groups (n = 11): group 1 – control group (administration of saline solution without stress); group 2 – chronic restraint stress (CRS) + administration of saline solution; group 3 – CRS + administration of ACTH 6-9 -PGP at a dose of 5 μg / kg; group 4 – administration of ACTH 6-9 -PGP at a dose of 50 μg / kg; group 5 – administration of ACTH 6-9 - PGP at a dose of 500 μg / kg. A histologic examination of the rat colon was performed. The histologic architecture of the colonic wall, the depth of crypts, and the number of goblet cells were assessed. Furthermore, the number of granulocytes, plasma cells, lymphocytes, macrophages, and mast cells was counted. Results . The study demonstrated that chronic (14 days) restraint stress resulted in the development of inflammations in the colonic wall of the animals. Intraperitoneal administration of ACTH 6-9 -PGP at doses of 50 and 500 μg / kg daily throughout the entire time of stress exposure prevented the development of stress-induced alterations observed in the control animals. At the same time, anti-inflammatory effects of the peptide in the colonic wall and a decrease in the level of corticosterone in the blood serum were noted. Conclusion . The results of this work and data from other studies on the effects of N-terminal analogs of ACTH indicate the need for studying the mechanisms of their effect on inflammation and searching for targets of ACTH 6-9 -PGP.

The peptide ACTH4–7-PGP has a wide spectrum of neuroprotective actions, including antioxidant and antidepressant effects in stress conditions. One important question is that of explaining the role of corticosterone in behavioral reactions on the background of repeated administration of ACTH4–7-PGP in chronic stress. The aim of the present work was to study the effects of ACTH4–7-PGP on behavioral reactions and corticosterone levels and their interaction in long-term stress in rats. ACTH4–7-PGP was given to male Wistar rats at doses of 5, 50, 150, and 450 μg/kg for 14 days 12–15 min before imposition of stress. The animals’ behavior was studied in the open field test and the elevated plus maze, and blood corticosterone concentrations were estimated by ELISA. In conditions of chronic stress, peptide was found to have an anxiolytic action and to decrease anxiety levels at doses of 50 and 150 μg/kg (p < 0.05–0.01). All ACTH4–7-PGP doses decreased serum corticosterone concentrations in stressed ats by 28.6–34.2% (p < 0.05). Correlation analysis showed that the decrease in anxiety on administration of ACTH4–7-PGP at a dose of 50 μg/kg had a direct and strong link with the decrease in the corticosterone level.

Влияние нейропептидов семейства меланокортинов на

In recent years studies devoted to the study of the mechanisms of regulation of physiological and pathophysiological processes are of particular interest in connection with the active development of molecular medicine. Stress caused by various biological, social and technogenic factors is an integral part of modern human life and is a non-specific reaction of the body to various extreme influences. Despite the formation of adaptive mechanisms under stress in the form of generalized activation of the body, focusing of attention and memory, stress-induced analgesia, under conditions of intense and prolonged influence of a negative factor, the central nervous system loses its ability to adapt and the processes of neurogenesis are often disturbed as a result of distress. This fact explains the development of stress-induced pathological processes in the central nervous system, which emphasizes the relevance of the search and study of the mechanisms of action of pharmacological agents exhibiting stress-protective and neurotropic properties. Melanocortins (N-terminal fragments of adrenocorticotropic hormone, fragments of proopiomelanocortin and their synthetic analogs) are characterized by pronounced neurometabolic, neuroregenerative and antistress activity. One of the possible mechanisms of action of melanocortins is the influence on the levels of expression in the central nervous system of neurotrophic factors that provide the main processes of regulation of homeostasis of the body. Brain Derived Neurotrophic Factor (BDNF) which is able to reduce the negative effects of hypoxic, toxic and stressful damage to brain cells, which is due to binding to tyrosine kinase B receptor and activation of the main metabolic cascades, is one of the effective regulatory proteins. Taking into account the fact that the question of the mechanisms of the stress-protective action of substances capable of protecting brain cells from the damaging effect of stress factors is relevant, the study of the effect of melanocortins on the level of neurotrophic factors is of scientific interest. The study was carried out on 70 male white rats of 6 months of age. Sensory contact in the absence of physical contact with the subsequent formation of aggressive and submissive types of behavior was used as an experimental model of «social» stress. Laboratory animals, taking into account the gradation by types of behavior, were divided into groups: a group of control / intact animals; a group of rats exposed to «social» stress for 20 days; a group of individuals who received Semax (ACTH(4-7)-Pro-Gly-Pro) at a dose of 100 μg / kg / day intraperitoneally from the 1st day of stress exposure for a course of 20 days; a group of animals that received ACTH(6-9)-Pro-Gly-Pro at a dose of 100 μg/kg/day intraperitoneally from day 1 of stress exposure for a course of 20 days. The BDNF level in the blood serum of white rats was assessed by the enzyme-linked immunosorbent assay using ELISA Kit for Brain Derived Neurotrophic Factor (BDNF) (USA). It was found that under conditions of «social» stress, a decrease in the level of BDNF was observed. The introduction of the studied melanocortins (ACTH(4-7)-Pro-Gly-Pro (Semax) and ACTH(6-9)-Pro-Gly-Pro) under conditions of induced «social» stress increases the concentration of BDNF in the blood serum of experimental animals. The study of the mechanisms of disturbances induced by experimental stress in various models showed that stress provokes the development of a depression-like state in rodents, which is accompanied by neuroplastic changes, including inhibition of neurogenesis in the hippocampus. Currently a large amount of experimental data has been accumulated, indicating that a pathological stress response contributes to a decrease in the level of BDNF. Deficiency of BDNF plays an important role in the pathophysiology of stress, inducing impairments of neurogenesis associated with impaired neuroplasticity, as well as dysfunction of the hypothalamic-pituitary-adrenal and neurotransmitter serotonergic systems. The effectiveness of therapy with stress protectors and antidepressants is due to their effect on neurogenesis and neuronal plasticity. Thus the fact of a decrease of BDNF under conditions of «social» stress established in the work and the positive effect of melanocortins (ACTH(4-7)-Pro-Gly-Pro (Semax) and ACTH(6-9)-Pro-Gly-Pro), contributing to the restoration of these parameters, indicates the effect of neuropeptides on the expression of BDNF and allows us to suggest a possible mechanism of the antistress effect. It should be noted that the serum level of brain neurotrophic factor can be considered as a biomarker of stress-induced disorders and affective disorders, as well as an indicator of the effectiveness of therapy with stress protectors. In addition, the level of BDNF in the blood serum can be considered as indicators of prognosis and evaluation of the effectiveness of therapy.

The effect of temperature, catalyst-to-NMDA ratio, and reaction time on the efficiency of deuterium incorporation into NMDA has been studied. It has been found that at temperatures above 180°С, incorporation of the label in NMDA changes insignificantly. The same pattern is observed when the reaction time changes. Increasing the time from 5 to 15 min increases the incorporation of deuterium by 2–3%. Reaction conditions have been selected that ensure the replacement of all protium atoms by deuterium in more than one third of NMDA molecules. It turned out to be possible to change the deuterium content in the substance by changing the deuterium-to-NMDA ratio. When deuterium gas reacted with a preparative amount of NMDA, on average of 2.76 deuterium atoms were included in the amino acid molecule.

This study is devoted to the experimental study of the immunocorrecting action of Semax (Met-Glu-His-Phe-Pro-Gly-Pro) and Selank (Thr-Lys-Pro-Arg-Pro-Gly-Pro) on the model of “social” stress formed as a result of sensory contact and inter-confrontation. Functional activity of the immune system of laboratory animals was assessed on the basis of standard immunopharmacological tests: delayed-type hypersensitivity reaction (DTH), direct agglutination test (DAT), latex test for studying the phagocytic activity of peripheral blood neutrophils, and evaluation of changes in the leukocyte formula. As a result of the experiment, it was found that, under the influence of “social” stress, changes in the immune response are multidirectional, which confirms the theory of “immune disbalance” under the action of stressors. As a result of studying the influence of Semax and Selank on the model of “social” stress, it was found that the drug proved to be an effective corrector, restoring the cellular and humoral immunogenesis reactions, the phagocytic activity of neutrophils, which indicates the presence of immunomodulating properties, and emphasizes the need for further studies in this scientific direction. This study expands the scientific research base in the field of immunoreaction under stress-induced conditions with the aim of further developing a pharmacological strategy for correcting the revealed disorders by means of substances of a neuropeptide structure.

Tetrapeptide KKRR, corresponding to the fragment ACTH(15-18), is the shortest fragment that binds to the ACTH receptor with high affinity, does not activate this receptor and prevents the binding of the whole hormone molecule, therefore, exhibits the properties of an ACTH receptor antagonist. The aim of the work was to study the effects of the peptide ACTH(15-18) (KKRR) and its analogue ACTH(15-18)PGP on the animal behavior in normal conditions and after acute stress induced by inescapable electric foot-shock. It has been shown that the peptides do not affect the anxiety level of Wistar rats in the norm. Pretreatment with ACTH(15-18) (250 mu g/kg) and its analog ACTH(15-18)PGP (50 and 250 mu g/kg) significantly decreases anxiety level in rats exposed to the acute electric footshock and attenuates stress-induced changes in serum corticosterone. The magnitude and duration of the anti-stress effects of the peptide ACTH(15-18)PGP significantly exceeds the magnitude and duration of the effects of its natural prototype.

Peptide derivatives of dopamine (DA) and serotonin (5-hydroxytryptamine, 5-HT) acylated with lauric acid (LA) and oleic acid (OA), including LA-Gly-Pro-DA, LA-Gly-Pro-5-HT, OA-Gly-Pro-DA, and OA-Gly-Pro-5-HT, were synthesized. A mass spectrometric method for assessing the content of the DA and 5-HT derivatives in phosphate buffered saline (PBS Am-E404 – 100, pH 7.4) was developed. It was shown that these compounds could penetrate through artificial membranes. A special mixture of these compounds was used for modeling a situation where the molecules of DAand 5-HT derivatives diffused through the membrane as a result of their competitive interaction, which allowed a reliable determination of which compounds in the mixture penetrated more easily through artificial membranes. The comparative permeability of the blood–brain barrier (BBB) was evaluated by the method of parallel artificial membrane permeability assay (PAMPA). It was established that derivatives LA-Gly-Pro-5-HT and LA-Gly-Pro-DA, which were acylated by LA, were most promising for overcoming the BBB.

In recent years, drug designers have increasingly focused on creating complex compounds containing biologically active molecules of various chemical classes in their structure. Such modifications increase the stability of resulting molecules in the organism and increase their ability to achieve the desired targeting effect. Regulatory peptides-based drugs are of particular interest. In this work, we combined the monoamines (serotonin or dopamine) and N-terminal-protected biologically active peptides or amino acids in a single compound and characterized the resulting molecules' enzymatic stability and possible molecular activity. Boc-Pro-5HT and Вос-Pro-DA were stable for at least 180 min of incubation in the presence of PEP, amino-and carboxy-peptidases, as well as blood plasma. This time is enough to reach their corresponding biological targets in the organism and become additional monoamines and regulatory peptides. It was also shown that these complex compounds possess specific targets on cell plasmatic membranes and can affect some neuroreceptor systems (GABA and Ach, in particular) as highly selective allosteric modulators. The above features make these molecules promising candidates for prodrugs and require further research on the mechanisms of their action.

Studying the effects of regulatory peptides on the stress-induced shifts in the bodily processes is of great fundamental and applied significance. Currently, a wide range of peptide neurotropic drugs, affecting the stress response development, are used in medicine, and new promising molecules are being studied. The study was aimed to assess the effects of the adrenocorticotropic hormone (ACTH) synthetic analog, ACTH(6-9)-Pro-Gly-Pro, administered at a dose of 5, 50 and 500 μg/kg, on the free-radical oxidation processes in Wistar rats, subjected to chronic restraint stress (CRS) during two weeks. Serum levels of 8-oxo-2'-deoxyguanosine (8-OHdG) and superoxide dismutase 3 (SOD3) were assessed by enzyme immunoassay, and the levels of thiobarbituric acid reactive substances (TBARS) were assessed by fluorimetric method. CRS lead to the significant increase in the 8-OHdG levels by 18.4% (p = 0.01) and the decrease in the SOD3 levels by 14.3% (p = 0.01), however, it had no effect on the levels of TBARS. ACTH(6-9)-Pro-Gly-Pro, administered at a dose of 5 and 50 μg/kg, significantly decreased the levels of 8-OHdG by 19.8% (p = 0.03) and 30% (p = 0.001), respectively. Thus, it was found that CRS resulted in oxidative stress in animals. ACTH(6-9)-Pro-Gly-Pro administration at a dose of 5 and 50 μg/kg inhibits the stress-induced free-radical oxidation processes.

We studied the effect of intraperitoneal administration ACTH(4-7)-PGP in doses of 5, 50, 150, and 450 μg/kg to Wistar male rats 12-15 min before modeling restraint stress on the morphofunctional state of the colon. In rats exposed to restraint stress, signs of atrophy and inflammatory reaction in the colon wall, changes in functional activity and number of mast cells, and increased serum level of corticosterone were observed. Administration of the peptide led to a decrease in corticosterone concentration, alleviated stress-induced pathomorphological changes, and promoted adaptation of the intestinal wall to stress. The positive effects of ACTH(4-7)-PGP can be determined by multifunctional nature of the physiological and pharmacological effects of the neuropeptide.