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.

The modern view on the role of glyprolines by metabolic syndrome.

The analysis of the literature data and own experimental studies on the effect of glyproline peptides on fat, carbohydrate metabolism, and hemostasis system when modeling metabolic syndrome in animals (rats) was carried out. Violations of fat and carbohydrate metabolism are characterized by hypercoagulation, increased glucose levels, dyslipidemia, and decreased rheological properties of blood. In this condition, the arginine- and lysine-containing glyprolines (PGP, PRP, RPGP, KKRRPGP, RKKRPGP, and KRRKPGP) at multiple (7 days) intranasal introduction had a complex effect on the hemostatic parameters, increasing antiplatelet, anticoagulant, and fibrinolytic activity of blood plasma.

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.

Effect of a New Synthetic Peptide Preparation AСTHPGP on the Hemostasis System in Rats.

We studied the effect of chronic intranasal and peroral administration of a new peptide preparation AСTHPGP 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.

[Oxoprolinic short peptides - potential pharmacological means of hypolidemic and antitrombotic actions].

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.

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.

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.

[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.

Mechanisms for glyproline protection in hypercholesterolemia.

Comparative analysis of the hypocholesterolemic and antithrombotic action of small regulatory glyproline peptides (Pro-Gly-Pro, Arg-Pro-Gly-Pro and Pro-Gly-Pro-Leu) was performed on an experimental hypercholesterolemia model of rats. Repeated intranasal introduction of glyproline peptides to fat-diet-fed animals led to more active functioning of the anticoagulation system (the anticoagulant and fibrinolytic properties of the plasma increased and platelet aggregation decreased) and to normalization of the total cholesterol level as a parameter of lipid metabolism. The largest anticoagulant and hypocholesterolemic effect was detected for the Pro-Gly-Pro-Leu peptide.

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.

[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.

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.

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.

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.

Anticoagulant activity and platelet aggregation in blood plasma from rats after intranasal administration of adenosine triphosphate and its complex with heparin.

Fourfold intranasal administration of ATP was followed by an increase in anticoagulant activity and decrease in platelet aggregation in blood plasma of healthy rats and, particularly, of animals with suppressed function of the anticoagulant system. These changes decrease the risk of the prethrombotic state. Complex of ATP and high-molecular-weight heparin decreased platelet aggregation only in the blood from healthy animals, but increased anticoagulant potential of plasma hemostasis in prethrombotic animals.

Changes in hemostatic parameters after intranasal administration of peptide Pro-Gly-Pro.

Anticoagulant activity, total and nonenzymatic fibrinolytic activity, and tissue plasminogen activator activity increased, while platelet aggregation and activity of factor XIIIa in rat blood plasma decreased over 3 h after single intranasal administration of proline-containing peptide Pro-Gly-Pro. Hemostatic parameters in rats 24 h after single administration of this peptide did not differ from the control level observed in animals receiving 0.85% NaCl.

Antithrombotic activity of heparin-ATP complex.

The complex of high-molecular-weight heparin and ATP prevented thrombus formation in the blood flow. Repeated intramuscular injection of the complex increased total fibrinolytic activity of the blood, nonenzymatic fibrinolysis, and plasma anticoagulant activity and significantly decreased platelet aggregation.

Correction effect of ATP on platelet aggregation and blood coagulation in vitro and in the presence of circulating thrombin in rats.

ATP added to plasma samples in concentrations of 5x10(-3)-5x10(-5) M in vitro decreased ADP-induced platelet aggregation. Platelet aggregation stimulated with thrombin under similar experimental in vitro conditions significantly decreased in the presence of 5x10(-6) M ATP and tended to decrease under the influence of ATP in concentrations of 5x10(-3) and 5x10(-7)-5x10(-9) M ATP. When endogenous thrombin in the circulation was stimulated by intravenous infusion of tissue thromboplastin, pretreatment with ATP (4 intramuscular injections, 0.