Comparative studies of anticoagulant and fibrinolytic effects of glyprolines Gly-Pro and Gly-Pro-Arg in conditions of immobilization stress

It has been shown that proline-containing peptides Gly-Pro and Gly-Pro-Arg in vitro had anticoagulant and nonenzymatic fibrinolytic activity. It was established that after intranasal introduction of these peptides to a rat, anticoagulant and fibrinolytic activity of enzymatic and nonenzymatic nature increased in the rat blood. The peptide protective effect against hypercoagulation induced by immobilization stress was found after repeated intranasal introduction of each peptide into the animal.     

Effect of the N-terminal fragment of substance P1-4 on the somatic manifestations of the stress reaction and on the catecholamine content of the adrenals in rats

The antistress affect of the substance P1-4 N-terminal fragment (ARG-Pro-Lys-Pro, 100 mkg/kg, i.p.) has been studied on the model of immobilization stress in rats. It was ascertained that the preparation of protective effect is revealed to the greatest extent on the exhaustion stage (48 h of immobilization), which served to prevent the lymphoid organs mass reduction and ulcer development and also accounted for greater adrenaline and noradrenaline content preservation in tissues and chromaffin cells of adrenal glands in stressed animals.     

Evaluation of adaptogenic activity profile of herbal preparation

The herbal formulation, AVM is a proprietary formula that consists of extracts of herbs that have been used in Indian traditional medicine to promote physical and mental health, improve defense mechanisms of the body and enhance longevity. AVM (500 and 1000 mg/kg) was tested for its adaptogenic activity by determining antistress, anabolic and immunomodulatory effects. In antistress activity, pretreatment with AVM significantly attenuated the changes in ascorbic acid (from blood and adrenal), cortisol (from plasma and adrenal) and adrenal gland weights induced due to restrain stress (physical immobilization). Its antistress effect at 1000 mg/kg was comparable to that of diazepam (5 mg/kg) treated group. Leucopenia, and anemia induced by cyclophosphamide (CYP) was shown to reduce significantly by AVM. Treatment of AVM + CYP had increased spleen and thymus weights significantly as compared to CYP alone treated group. The anabolic activity was evaluated by weight gain of the levator ani muscle, ventral prostrate gland and seminal vesicles in rats as compared to untreated control.     

Study of the relationship between analgesic activity and structure of synthetic melanocortin analogs

Melanocortins, peptides of the family of adrenocorticotropic (ACTH) and melanocyte-stimulating (MSH) hormones, have a wide range of physiological activity. Heptapeptide semax (MEHFPGP) is an analog of the ACTH_4–10 fragment. Previously, pronounced nootropic and neuroprotective activities were shown for this peptide; in addition, it decreases pain sensitivity in animals. In this work, the relationship between analgesic activity of the peptide and its structure was studied. The following analogs of the N-terminal ACTH fragments were used: rMEHFPGP, where r is glucuronic acid, KEHFPGP, GEHFPGP, EHFPGP, HFPGP, and ERP. The peptides were administered intraperitoneally at doses of 0.015, 0.05 and 0.5 mg/kg. Rat pain sensitivity was assessed using the paw-withdrawal test. Truncations of the N-terminal residues eliminated the analgesic activity. The peptide analgesic effect was observed after the replacement of the N-terminal methionine with lysine or after the attachment of glucuronic acid to the methionine, while the peptide with glycine instead of the methionine had no effect on pain sensitivity. Hence, the amino acid at position 1 of semax analogs plays a key role in mediating the analgesic effects of the peptides.     

Regulatory effect of microbial alkyloxybenzenes of different structure on the stress response of yeast

The effect of alkyloxybenzenes (AHBs) belonging to the class of alkylresorcinols differing in the degree of hydrophobicity--C7-AHB and more hydrophobic Cl12-AHB--on the resistance of Saccharomyces cerevisiae cells to heat shock and oxidative stress of lethal intensity was studied. Depending on structure and concentration, AHB added 2 h before exposure to stress had either an antistress or stress-potentiating effect on yeast cells in the mid-logarithmic growth phase. C7-AHB at concentrations 0.25-0.5 g/l caused a two- to fivefold increase in the resistance of yeast cells to hydrogen peroxide (30-150 mM), whereas Cl2-AHB reduced it at all concentrations. C7-AHB and Cl2-AHB had a similar effect on yeast subjected to heat shock (45 degrees C, 30 min). It was found that the degree of the protective effect of C7-AHB and potentiating effect of Cl2-AHB depended on the nature of the stressor, being more pronounced in heat shock. The environmental significance of the antistress and stress-potentiating effects of microbial AHBs is discussed.     

Regulatory effect of microbial alkyloxybenzenes of different structure on the stress response of yeast

The effect of alkylhydroxybenzenes (AHBs) belonging to the class of alkylresorcinols differing in the degree of hydrophobicity—C7-AHB and more hydrophobic C12-AHB—on the resistance of Saccharomyces cerevisiae cells to heat shock and oxidative stress of lethal intensity was studied. Depending on structure and concentration, AHB added 2 h before exposure to stress had either an antistress or stress-potentiating effect on yeast cells in the mid-logarithmic growth phase. C7-AHB at concentrations 0.25–0.5 g/l caused a two-to fivefold increase in the resistance of yeast cells to hydrogen peroxide (30–150 mM), whereas C12-AHB reduced it at all concentrations. C7-AHB and C12-AHB had a similar effect on yeast subjected to heat shock (45°C, 30 min). It was found that the degree of the protective effect of C7-AHB and potentiating effect of C12-AHB depended on the nature of the stressor, being more pronounced in heat shock. The environmental significance of the antistress and stress-potentiating effects of microbial AHBs is discussed.     

Role of the peripheral catecholaminergic systems in the antistress action of neuropeptides

The mediator activity of the peripheral catecholaminergic systems (the adrenergic nerves of dura mater and the concentrations of noradrenaline and adrenaline in the adrenals of rats) during dynamic and immobilization stress was investigated with the help of fluorescent microscopy and spectrofluorometry. Neuropeptides--dalargin and another enkephalin analog--were injected intraperitoneally, 150 mg/kg. A visible antistress action of these neuropeptides has been demonstrated, it was more marked after treatment with dalargin. The role of peripheral catecholaminergic system in the mechanism of stress-protective effects of neuropeptides is discussed.     

Studies of the aminopeptidase proteolysis of semax analogues with different <Emphasis Type="Italic">N</Emphasis>-terminal amino acid residues

Proteolysis of semax (Met-Glu-His-Phe-Pro-Gly-Pro, Sem) and its analogues with the substitution of Ala, Gly, Thr, or Trp for the N-terminal Met was studied. This substitution was shown to change the degradation rate of these peptides by leucine aminopeptidase (EC 3.4.11.2, Sigma, Type VI, 9.2 activity units/mg). [Ala¹]Sem, [Gly¹]Sem, and [Thr¹]Sem (the semax analogues) proved to be more stable to the proteolysis than semax itself. It was demonstrated that the primary product of the proteolysis was His-Phe-Pro-Gly-Pro (Sem-5). In the case of [Trp¹]Sem, the comparable amount of Glu-His-Phe-Pro-Gly-Pro (Sem-6) was found to be formed along with Sem-5. In was established that all the studied semax analogues could be used as inhibitors of its proteolysis.     

The effect of glyprolines on stressogenic disorders in the rat behaviour

Protective and antistress effects of three glyprolines--PGP, PG and GP, were studied. Stress influences produced typical changes of behavioural activity of rats in the elevated pluz-maze and the hole-board tests. These changes suggest a significant enhancement of anxiety and a drop of the level of orientation-investigative activity. A preliminary (15 minutes before stress agent) intraperitoneal administration of PGP or GP in doses of 3.7 microm/kg significantly decreased stress disturbances of behaviour. Analysis of these data shows to the possibility of PGP and GP influences on the CNS structures, which take part in the organism reciprocal reactions to stress factor. The peptide GP at equimolar dose didn't possess pronounced protective properties and just slightly decreased stress disturbance of behavioural activity of rats.     

Effect of Modification of the N-Terminal Region of Semax on the Expression of Nootropic Effect of Semax Analogs

A comparative study of nootropic activity of semax (MEHFPGP), an analog of ACTH_4–10, and some of its derivatives, in which the N-terminal methionine was modified or substituted with other amino acid residues, was performed. The effect of these peptides on learning of albino rats in tests with positive (food) and negative (pain) reinforcement was studied. In the case of modification of methionine by attachment of the gluconic-acid residue or substitution of methionine with lysine, the nootropic effect of the peptide was retained. The substitution of methionine with tryptophan or serine resulted in a decrease in the nootropic activity. The substitution of methionine with glycine, threonine, or alanine caused a complete loss of the nootropic activity of the peptide. Therefore, the amino acid residue located at position 1 of the heptapeptide analog semax, plays a key role in retaining the nootropic effects of the peptide and determines the degree of their expression.__________Translated from Izvestiya Akademii Nauk, Seriya Biologicheskaya, No. 4, 2005, pp. 460–466.Original Russian Text Copyright © 2005 by Glazova, Sebentsova, Levitskaya, Andreeva, Alfeeva, Kamenskii, Myasoedov.     

Modulating effect of opioid peptides on hemopoiesis in stress

The influence of leu-enkephalin and dalargin on the blood system was studied during immobilization stress in mice. The early transmitted reactions of the peripheral blood were shown to decrease upon single drug infusions after immobilization. At later terms the activation of bone marrow hematopoiesis was not registered in mice receiving opioid peptides in contrast to the control animals. It correlates with drug-induced decrease in the mitotic activity of bone-marrow cells. Suppressive effect of opioids on hematopoiesis during stress was connected with their decreasing effect on corticosteroid level in the animal plasma. The latter can suggest indirect influence of enkephalins on bone marrow hematopoiesis in immobilization stress.     

Prophylactic effects of sodium oxybutyrate and lithium oxybutyrate on stress-induced depression of the activity of normal killers in mice

The possible use of sodium hydroxybutyrate and lithium hydroxybutyrate for the prevention of the decrease in splenic natural killer activity has been studied in CBA mice upon 6-hour immobilization stress. Both agents proved to be effective in preventing stress-induced depression of NK activity. However, a protective effect of lithium hydroxybutyrate was observed at a dose 4 times lower than that of sodium hydroxybutyrate.     

Proteolysis of semax analogues with different N-terminal amino acids by aminopeptidases

Proteolysis of semax (Met-Glu-His-Phe-Pro-Gly-Pro, Sem) and its analogues ([Ala1]Sem, [Gly1]Sem, [Thr1]Sem, [Trp1]Sem) that are differ from semax in substitution of N-terminal Met residue were studied. It is shown that such replacement changes the rate of peptides degradation by N-aminopeptidases (EC 3.4.11.2, Sigma, Type VI, 9.2 units. Akt. / mg). [Ala1]Sem, [Gly1]Sem and [Thr1]Sem semax analogues proved to be more stable to proteolysis than semax (Sem), and their initial product of proteolysis is His-Phe-Pro-Gly-Pro (Sem-5). For triptophan analogue both Glu-His-Phe-Pro-Gly-Pro (Sem-6) and Sem-5 product are formed in similar quantities. It is found that all investigated analogues can be used as inhibitors in Sem proteolysis.     

Possible role of NO modulators in protective effect of trazodone and citalopram (antidepressants) in acute immobilization stress in mice

Stress is an aversive stimulus which disturbs physiological homeostasis and is reflected on a variety of biological systems. The present study was designed to investigate the nitric oxide mechanism in neuroprotective effect of trazodone and citalopram against acute immobilization-induced behavioral and biochemical alteration in mice. Mice were immobilized for a 6 h. Acute immobilization stress caused anxiety, hyperalgesia, impaired locomotor activity and oxidative damage. Pretreatment with trazodone and citalopram significantly reversed immobilized stress-induced behavioral and biochemical alterations. L-arginine, pretreatment with trazodone or citalopram significantly reversed their protective effects. However, L-NAME or methylene blue pretreatment with trazodone or citalopram significantly potentiated their protective effects alone. Results suggest the involvement of nitric oxide pathways in the protective effect of trazodone and citalopram against immobilization stress induced behavioral and biochemical alterations.     

Nitric oxide storage in rats of various genetic strains and its role in the antistressor effect of adaptation to hypoxia

Adaptation to hypobaric hypoxia induced a gradual increase in the NO production along with a progressive NO storage in vascular wall. Unadapted August rats were more resistant against stress-induced stomach ulceration than the Wistar rats. Following a 6-day adaptation rats of both strains revealed a protective antiulcerogenic effect. A long-term adaptation potentiated the stress damage of the stomach rather than protected against it. A higher basal NO production seems to provide a more efficient antistress defence in the August rats. An intense NO storage may create a relative NO shortage and thus predispose to stress-induced vasoconstriction and ulceration.     

Interaction of the effects of glucose and stress hormones on the activity of key enzymes of liver glycogen metabolism in rats

Endogenous corticosterone released in protracted immobilization stress fails to increase the activity of liver glycogen synthase, perhaps because of the inhibition of synthase phosphatase by phosphorylase a. It was also found, that in rats subjected to acute immobilization stress the stimulation of the activity of both synthase a and total forms by glucose administered i.v. is depressed. Finally, in rats fasting for 24 h a paradoxical augmentation by glucose of the stimulatory effect of glycogenolytic hormones released in acute immobilization stress on phosphorylase a activity was observed.     

Multifunctional antistress effects of standardized aqueous extracts from Hippophae rhamnoides L.

This study aims to screen and identify the multi-mechanism antistress effects of an extract of Hippophae rhamnoides L. (HR) leaves on corticosterone (CORT)-induced injury, N-methyl-d-aspartate (NMDA) receptor and serotonin 6 (5-hydroxytryptamine 6, 5-HT₆) receptor activity tests (in vitro), electric foot shock and forced swimming tests (FSTs) (in vivo), and tests for hippocampal CORT and monoamine levels (ex vivo), in search of active principles and underlying mechanisms of action. We confirmed that the water extract of HR (HRW) and various ethanol extracts of HR confer protective effects against CORT-induced impairments in SH-SY5Y cells and antagonistic effects on NMDA receptors and the 5-HT₆ receptor by using primary cultured rat hippocampal neurons and a stable 5-HT₆ receptor-expressing cell line, respectively. In addition, we confirmed the antistress effects of HRW in an electric foot shock stress model in mice and explored the underlying mechanisms of its action. We observed that HRW treatment significantly reversed the reduction in immobility times and increased climbing times in FSTs induced by electric foot shocks in the stress model. The levels of CORT, dopamine, and norepinephrine were increased, and the level of serotonin in the hippocampus was decreased in the electric foot shock stress model. The standardized HRW effectively restored abnormal CORT and monoamine levels in the hippocampus that were induced by stress. The results of the present study demonstrate that the standardized HRW produces novel multifunctional antistress effects.     

Adaptogenic activity of a glyco-peptido-lipid fraction from the alcoholic extract of Trichopus zeylanicus Gaertn.

A glyco-peptido lipid fraction ("AF") from the alcoholic extract of Trichopus zeylanicus Gaertn. was evaluated for putative antistress activity in a battery of tests. "AF" exhibited significant antistress activity in dose dependent manner in all the parameters studied, against the different stresses use to induce non-specific stress. Ashwagandha, the commercial extract of Withania somnifera roots was used as control: A preliminary acute toxicity study in mice showed a good margin of safety, as the ALD50 value was more than 3000 mg/kg body wt. p.o. with no signs of abnormalities.     

Immobilization stress-induced antioxidant defense changes in rat plasma: Effect of treatment with reduced glutathione

• 1.1. We examined immobilization stress-induced antioxidant defense changes in rat plasma and observed the antioxidant effect of reduced glutathione (GSH) administration on these changes.
• 2.2. Immobilization stress induced severe bleeding in the stomach and a significant increase in plasma levels of thiobarbituric acid receives substances (TBARS).
• 3.3. Immobilization stress induced a significant decrease in plasma iron-binding, ironoxidizing protections and radical scavenging activity.
• 4.4. Plasma levels of ascorbic acid, ascorbyl radical and superoxide dismutase activity remained unchanged following immobilization stress.
• 5.5. Treatment with GSH showed a significant protective effect on stomach bleeding, on the increase in plasma TEARS, and on the decrease of iron-binding, iron-oxidizing protection and radical scavenging activity in plasma.
• 6.6. These results suggest that immobilization stress induces generation of reactive oxygen species and decreases the endogenous antioxidant defenses, which can be attenuated by extracellular administration of antioxidant GSH.

     

The effect of semax and its C-end peptide PGP on expression of the neurotrophins and their receptors in the rat brain during incomplete global ischemia

Neurotrophins regulate key function of nervous tissue cells. Analysis of neurotrophins mRNA expression is an appropriate tool to assess therapeutic efficiency of the anti-stroke drugs. We have analyzed the effect of synthetic peptide semax and its C-terminal Pro-Gly-Pro tripeptide upon mRNAs expression of neurotrophins Ngf, Bdrf, Nt-3 and their receptors TrkA, TrkB, TrkC, p75 in rat frontal lobes, hippocampus and cerebellum after bilateral common carotid artery occlusion. The animals were decapitated 30 min, 1, 2, 4, 8, 12, 24 h after the operation. The mRNA expression of neurotrophins and their receptors was assessed by relative quantification using real-time RT-PCR. Our showed that ischemia causes a significant decrease in gene expression in the hippocampus. Semax and PGP affected the expression of neurotrophins and their receptors predominantly in the frontal cortex and hippocampus of the ischemized animals. In the frontal cortex, Semax treatment resulted in a decrease of mRNA level of receptors, while PGP treatment increased the level of these mRNA. Maximal neuroprotective effect of both peptides has been observed in the hippocampus 12 h after occlusion. A decrease of gene expression of neurotrophins and their receptors caused by the occlusion was overcome by Semax and PGP. These results clarify the semax mechanism of and present certain features of mRNA's expression of neurotrophins and their receptors in experimental conditions.