Effect of peptide Pro-Gly-Pro on stress-induced behavioral changes in rats

Tripeptide PGP in a dose of 1 mg/kg had a correcting effect on behavioral disorders in rats induced by stress exposure (forced swimming). PGP prevented the increase in anxiety and decrease in orientation and exploratory activity. Our results suggest that the effect of this peptide is realized via central nervous structures involved in organism’s response to stress factors. Translated fromByulleten’ Eksperimental’noi Biologii i Meditsiny, Vol. 138, No. 7, pp. 9–11, July, 2004     

Pancreatic hormone amylin and integrity of the gastric mucosa

The paper presents experimental findings of some possible mechanisms of protective antiulcerous action of amyline. Amyline is the second beta-cell pancreatic hormone, which has been just recently discovered. The authors have studied the effects of amyline on gastric secretion, mast cell functions, mesenteric lymphatic microvascular contractility, i.e. on individual aggressive and protective factors of the gastric mucosa. Amyline has been found to inhibit basal acid gastric secretion and the secretion stimulated by vagal irritation. The peptide reduces the secretory activities of mast cells. Amyline given to animals increases the heparin saturation index of mast cells and decreases the degranulation index. Amyline-induced stabilization of mast cells appears to followed by the decreased release of histamine and other damaging substances. The stimulating effect of amyline on the contractile activity of mesenteric lymphatic vessels was recorded in rats. Amyline increases both the frequency and amplitude of their contractions. The increased lymph flow that is closely associated with microcirculation promotes the maintenance of tissue homeostasis. Therefore, the protective antiulcerous properties of amyline reduce the action of aggressive agents on the gastric mucosa and stimulate protective ones.     

Protective and therapeutic effects of glyprolines in psychoemotional stress induced by cholecystokinin-4 injection

Experiments on outbred albino male rats showed that psychoemotional stress induced by intraperitoneal injection of cholecystokinin-4 (100 μg/kg) increased anxiety, impaired orientation and exploration activities in the elevated plus-maze and hole-board tests, and increased the level of depression of Porsolt test. Preliminary intranasal administration of glyprolines (15 min before cholecystokinin) in a dose of 3.7 μmol/kg prevented the development of stress-induced behavioral disturbances. Administration of peptides 30 min after cholecystokinin-4, i.e. to rats with developed behavioral disturbances, almost completely abolished these disturbances. __________ Translated from Byulleten’ Eksperimental’noi Biologii i Meditsiny, Vol. 145, No. 3, pp. 270–274, March, 2008     

Blood filtration through polymer gauze filters

Translated from Khimiko-Farmatsevticheskii Zhurnal, No. 10, pp. 68–71, September–October, 1991.     

Functional outcomes of structural peculiarities of striated muscle tropomyosin

Tropomyosin is a dimer coiled-coil actin-binding protein. Adjacent tropomyosin molecules connect each other ‘head-to-tail’ via an overlap junction and form a continuous strand that winds around an actin filament and controls the actin–myosin interaction. High cooperativity of muscle contraction largely depends on tropomyosin characteristics. Here we summarise experimental evidence that local peculiarities of tropomyosin structure have long-range effects and determine functional properties of the strand, including changes in its bending stiffness and interaction with actin and myosin. Point mutations and posttranslational modifications help to probe the roles of the conserved ‘non-canonical’ residues, clusters of stabilising and destabilising core residues, and core gap in tropomyosin function. The data suggest that tropomyosin structural lability including a diversity of homo- and heterodimers of different isoforms provide a balance of stiffness, flexibility, and strength of interaction with partner sarcomere proteins necessary for fine-tuning of Ca²⁺ regulation in various types of striated muscles.

     

Tripeptide Pro-Gly-Pro Prevents Disturbances in Osmotic Resistance of Rat Erythrocytes under Conditions of Inflammation

The development of inflammation (experimental model of peritonitis induced by administration of sodium thioglycolate) was accompanied by a decrease in osmotic resistance of erythrocytes. Changes in osmotic resistance of erythrocytes associated with preliminary (15 min before induction of inflammation) administration of peptide Pro-Gly-Pro were significantly weaker, and the percentage of hemolyzed cells was reduced. The peptide injected against the background of developed inflammation (1 h 45 min after induction) had no corrective effect on osmotic resistance. During in vitro experiments, Pro-Gly-Pro did not affect hemolysis of intact erythrocytes. These results support the assumption that prophylactic administration of the peptide protects erythrocyte membranes and increases their osmotic resistance.     

The characteristics of the changes in the aortic endothelium of old rabbits administered adrenaline

The effect of sharp increase of arterial pressure and blood adrenalin content on the vascular endothelium increases with age. Structural disorders and disturbances in permeability of aortic endothelium after 30-minute adrenalin infusion are more marked in old rabbits. This may be among the factors which induce intensified development of preatherosclerotic changes in the vessels.