Participation of Nitric Oxide in the Realization of Hemostatic Effects of Glyproline Peptides.

The involvement of nitric oxide in the responses of the hemostasis system to the appearance of proline-containing peptides in the blood was studied in experiments on rats. It was shown that a single intranasal administration of peptides PGP, RPGP, and PGPL to rats led to an increase in fibrinolytic, anticoagulant, and antiplatelet potential of blood. The use of the non-selective NO-synthase blocker L-NAME almost completely inhibited the anticoagulant effects of the glyprolines. It was found that the mechanism of the anticoagulant-fibrinolytic and antiplatelet action of glyproline peptides is determined by the activation of the enzymatic pathway of nitric oxide formation. The obtained results revealed the involvement of nitric oxide in the implementation of hemostatic and vascular-endothelial functions of the organism.

Thromboelastographic Research of Arginine-, Leucine and Lysine-Containing Peptides.

Anticoagulant effects of 12 short peptides of the glyproline series - Arg-Glu-Arg-Pro-Gly-Pro (RERPGP), Arg-Glu-Arg-Val-Gly-Pro (RERVGP), Arg-Glu-Arg-Gly-Pro (RERGP), Arg-Pro-Gly-Pro (RPGP), Pro-Leu-Pro (PLP), Pro-Leu-Pro-Ala (PLPA), Pro-Gly-Pro-Leu (PGPL), Phe-Pro-Leu-Pro-Ala (FPLPA), Pyr-Arg-Pro (PyrRP), Lys-Lys-Arg-Arg-Pro-Gly-Pro (KKRRPGP), Arg-Lys-Lys-Arg-Pro-Gly-Pro (RKKRPGP), and Lys-Arg-Lys-Pro-Gly-Pro (KRKPGP) in concentrations of 10-3 and 10-2 mg/ml in vitro was demonstrated by the thromboelastographic method. The effects of 6 peptides ((RERPGP, RPGP, PLP, PLPA, RKKRPGP, and KKRRPGP) were also observed in vivo after intranasal or oral administration. Changes in the studied thromboelastographic parameters towards hypocoagulation in comparison with the control group were noted. Arginine and leucine glyprolines produced the maximum anticoagulant effect.

Effect of a New Synthetic Peptide Preparation AСTH15-18PGP on the Hemostasis System in Rats.

We studied the effect of chronic intranasal and peroral administration of a new peptide preparation AСTH15-18PGP in a dose of 100 mg/kg body weight on the state of vascular-platelet and plasma hemostasis in animals. It was found that this synthetic regulatory peptide administered intranasally can produce antiplatelet, anticoagulant, and antifibrin-stabilizing effects on the blood plasma in healthy rats. In both administration routes, the peptide induced activation of the anticoagulation system of the hemostasis by increasing enzymatic and non-enzymatic fibrinolysis; after intranasal administration, the fibrinolytic effects were more pronounced.

The Status of the Hemostasis System under the Influence of Proline Peptides during the Development of Experimental Metabolic Syndrome.

A comparative study of the influence of regulatory proline peptides Pro-Gly-Pro, Pro-Arg-Pro, Pro-Gly-Pro-Leu, and Arg-Pro-Gly-Pro on the state of the hemostasis system was carried out in an experiment on male rats with metabolic syndrome. Under these conditions, repeated (7-fold) intranasal administration of the peptides in a daily dose of 50 µg/kg resulted in an increase in the anticoagulant potential of the blood, namely, in an increase in the anticoagulant, fibrinolytic, and antiplatelet activity 20 h and 7 days after the last peptide injection. The arginine-containing peptide Arg-Pro-Gly-Pro had the most pronounced and stable effect on haemostasis under these experimental conditions.

Regulation of Primary Polymerization of Fibrin by Blood Anticoagulant System Components.

Experimental data on the involvement of the blood anticoagulant system components (heparin complex compounds, short regulatory peptides) in fibrin formation processes are presented. Inhibition of thrombin activity and interactions of short glyproline peptides and their heparin complexes with fibrin monomer molecules are demonstrated. Peptides and their heparin complexes prevent the formation of primary polymeric fibrin and exhibit fibrin-depolymerizing activity on the formed polymeric fibrin. The mechanisms underlying the effects of heparin complexes on degradation of fibrin not stabilized with factor XIIIa is discussed on the basis of the results of spectral analysis and coagulation tests.

Antithrombotic Protective Effects of Arg-Pro-Gly-Pro Peptide during Emotional Stress Provoked by Forced Swimming Test in Rats.

Blood coagulation was enhanced and all factors (total, enzyme, and non-enzyme) of the fibrinolytic system were suppressed in rats in 60 min after forced swimming test. Argininecontaining tetrapeptide glyproline Arg-Pro-Gly-Pro administered prior to this test activated fibrinolysis and prevented hypercoagulation. Administration of this peptide in 5 min after swimming test also enhanced anticoagulant, fibrinolytic, and antithrombotic activity of the blood. Therefore, glyproline Arg-Pro-Gly-Pro exerted both preventive and curative effects on the hemostasis system and prevented enhancement of blood coagulation provoked by emotional stress modeled by forced swimming test.

[Peptide Regulation of Metabolic Processes under Hypercholesterinemia Conditions of an Organism].

The participation of short glyproline peptides in regulating the metabolic processes of the body has been established. Experimental hypercholesterolemia and the development of metabolic syndrome in rats was caused by including foods with excess animal fat and carbohydrates in the diet, which eventually led to increased levels of cholesterol, triglycerides, and the atherogenic lipoproteins; hypercoagulation; and increased blood sugar. It was noted that glyprolines with different structures possess a unique combined effect on fat and carbohydrate metabolism, normalizing the characteristics of the lipid profile and blood sugar and protecting the organisms of animals from increased blood clotting. The idea of peptide regulation of the hemostatic system and metabolism of fats and carbohydrates in the development of metabolic syndrome was formulated.

Hypoglycemic and anticoagulant effects of tetrapeptide Pro-Gly-Pro-Leu in hypercholesterolemia.

In rats with experimental hypercholesterolemia, 7-fold intranasal administration of the peptide Pro-Gly-Pro-Leu in a dose of 200 µg/kg body weight prevented the increase in blood glucose level and produced an anticoagulant effect.

Anticoagulant effects of arginine-containing peptide Arg-Pro-Gly-Pro under conditions of immobilization stress.

Anticoagulant, fibrinolytic, and antiplatelet effects of RPGP peptide were found in animals under stress conditions caused by single or repeated immobilization. The observed properties of the peptide extend the study of agents protecting the organism under conditions of hypercoagulation occurring under stress conditions and help to re-evaluate the role of glyprolines as contributors to the maintenance of adaptation capacities in various pathologies.

[The modern concept of the regulatory role of peptides of the glyproline family in the correction of hemostasis system function during development of diabetes mellitus].

The experimental data on the therapeutic and prophylactic antidiabetogenic effect of di-, tri-, and tetrapeptides of the glyproline family with the additional inclusion of arginine or leucine at different positions are presented. The results are obtained using two animal models: with insulin-dependent diabetes mellitus (type 1), and persistent hyperglycemia similar to development of non-insulin-dependent diabetes mellitus (type 2) in humans. It is shown that repeated intranasal administration of Pro-Gly, Pro-Gly-Pro, Pro-Gly-Pro-Arg, Pro-Gly-Arg, Arg-Pro-Gly, Arg-Pro-Gly-Pro, Gly-Pro-Arg, Pro-Arg-Gly, Pro-Gly-Pro-Leu, Leu-Pro-Gly-Pro peptides to rats with hyperglycemia of different etiology led to the combined normoglycemic and anticoagulant effects in the blood plasma. The concept of the regulatory role of short proline-containing peptides, involving the universality of their action in the organism and directed towards the regulation of both hemostasis and insular systems in a variety of their physiological and clinical manifestations, was formulated.

Anticoagulant, fibrinolytic, and hypoglycemic effects of tetrapeptide Arg-Pro-Gly-Pro.

It was found that 3-fold intranasal administration of Arg-Pro-Gly-Pro peptide in a dose of 1 mg/kg body weight under conditions of experimental persistent hyperglycemia prevents the development of diabetes in experimental rats and produces normoglycemic, anticoagulant, fibrinolytic, and antiplatelet effects.

Effects of peptide Pro-Gly-Pro-Leu under conditions of normal hemostasis and thrombus formation in rats.

Tetrapeptide Pro-Gly-Pro-Leu in vitro effectively inhibited platelet aggregation over the entire range of studied concentrations (10(-12)-10(-3) M). In concentrations of 10(-9)-10(-3) M it exhibits fibrinolytic activity and in concentrations of 10(-5)-10(-3) M has anticoagulant properties. Under in vivo conditions the analyzed tetrapeptide in a dose of 1 mg/kg increased anticoagulant, total and fibrin depolymerizating activities and increased activity of plasminogen activator. Intravenous administration produced more pronounced anticoagulant effect and leads to a greater increase in activity of plasminogen activator than intranasal administration. Tetrapeptide Pro-Gly-Pro-Leu also exerts antithrombotic effect. Preliminary repeated intranasal administration of the peptide before blood clot formation reduces the weight of fresh fibrin clots.

Anticoagulation and antiplatelet effects of semax under conditions of acute and chronic immobilization stress.

The effects of semax on anticoagulant, fibrinolytic, and platelet components of the anticoagulation system were studied on albino rats under conditions of acute and chronic immobilization stress. Semax exhibited a protective antistress effect after repeated intranasal administration under conditions of hypercoagulation developing in response to immobilization stress of different degree. The effect manifested in stimulation of the anticoagulation system.

Anticoagulant effects of a complex of high molecular weight heparin and arginine.

Heparin forms a complex compound with arginine in a pure system, which was shown by biochemical methods. A method for obtaining the complex in vitro has been developed. At arginine/heparin molar ratio of 3:1 the complex exhibited anticoagulant, antiplatelet, and fibrin-depolymerization activities. High fibrin-depolymerization and anticoagulant activities were documented in the blood of animals 10 min after intravenous injection of the arginine-heparin complex, in contrast to the picture after injection of the complex components (heparin and arginine) alone.

[Oxoprolinic short peptides - potential pharmacological means of hypolidemic and antitrombotic actions]. / Oksoprolinovye korotkie peptidy ­ potentsial'nye farmakologicheskie sredstva gipolipidemicheskogo i antitromboticheskogo deistviia.

One of the most urgent and important tasks of modern biological and medical research is the search and research of pharmacological agents that combine lipid-lowering and antithrombotic effects in the organism. The unique effects of the regulatory peptides of the oxoproline series (5-oхo-Pro-His-Pro-NH2, 5-oxo-Pro-Trp-Pro and 5-oxo-Pro-Arg-Pro or 5-oхo-Pro-His-Pro-NH2, Pyr-Trp-Pro and Pyr-Arg-Pro) have been found in rats with hypercholesterolemia (metabolic syndrome). Multiple intranasal of these peptides to animals with developed hypercholesterolemia increased anticoagulant, fibrinolytic and antiplatelet potential of the blood and simultaneously lowered increased concentrations of total cholesterol, low-density lipoprotein cholesterol and triglycerides. In addition, they contributed to the normalization of blood glucose levels. A week after the last admistration of these peptides, the hypocholesterolemic, normoglycemic and anticoagulant effects persisted. The relationship between the structure of peptides of the oxoproline series and their functional properties is discussed. A conclusion is made about the prospects of further studies of oxoproline peptides as drugs that combine antithrombotic effects with the improvement of fat metabolism in the body.

Natural and hybrid ("chimeric") stable regulatory glyproline peptides.

The present concept of relative instability of regulatory peptides (RPs) in organisms must be amended. The recently characterized family of glyprolines and some other prolyl-glycyl-proline (PGP)-containing oligopeptides show the stability quite comparable with those of major pharmacological preparations. The ability of glyprolines to pass gastro-enteric tract barriers opens ways to per-oral administration of this new group of drugs such as semax, selank and their fragments. The most interesting approach is the creation of hybrid ("chimeric") peptide drugs combining the unmodified representatives of various natural RPs that distinctly manifest their inherent physiological activities and cooperate with each other in stabilization of whole peptide in vivo. As the result, the activity of such peptides as semax and selank may have value in a vide variety of pathological processes.