[Neuropeptide Y: its diversity and the apparent contradictoriness of its functions. An analysis of its possible mediated effects]

The review of NPY functions summarizes so fare accumulated data of its physiological effects. The estimation of heterogeneity of NPY receptors in responding reactions is made. The analysis of possible direct and indirect NPY effects is performed including cascade mechanism of other peptides releasing. Peptide cascade regulation modeling software created on database programming language Visual FoxPro 5.0 allows to trace several induction steps and estimate possible contribution of each peptide into final spectrum of biological activity.

Pargyline conjugate-induced long-term activation of monoamine oxidase as an immunological model for depression

We describe an animal model of long-term depression based on active immunization of albino rats against BSA-conjugated inhibitor of monoamine oxidase, antidepressant, pargyline. Immunization resulted in anti-pargyline antibody formation and significant activation of monoamine oxidase A in brain. Immunized rats demonstrated potent decrease of motor, orientation and exploratory activity, increase of the immobility time ("despair") in Porsolt test, as well as notable signs of fear and anxiety in elevated plus maze. The cognitive processes were not significantly affected: the speed of learning with negative and positive reinforcement was not diminished. Complex effect on craving for alcohol (long-term suppression after short-term increase) was also demonstrated. The long-term (more than 45 days) depression achieved in this model makes it potentially important tool for testing new antidepressant pharmaceuticals.

The effects of a novel analog of the C-terminal fragment of vasopressin on the behavior of white rats

The effects of an arginine-vasopressin fragment, Ac-D-MPRG, on the movement activity and orientational-investigative activity of white rats were studied. Peptide was given intranasally at doses of 0.001, 0.01, 0.1, 1, and 10 micrograms/kg 1 h before testing. All peptide doses increased vertical movement activity in an open field test and hole board test and decreased grooming levels in both tests. The peptide had no effect on horizontal movement activity. Analysis of these results led to the conclusion that Ac-D-MPRG increases orientational-investigative activity, but, unlike arginine-vasopressin, does not affect non-motivated movement activity.

[The effect of influenza virus hemagglutinin on erythrocytes and thrombocytes]

We studied the effect of influenza virus hemagglutinin on the volume of erythrocytes and aggregation activity of thrombocytes. Hemagglutinin proved to increase the erythrocyte volume, which ends in their lysis, and to induce disaggregation of the thrombocytes. The effect of hemagglutinin on the erythrocytes and thrombocytes was dose-dependent.

[Peptides as inhibitors of thrombin coagulation activity and of thrombocyte aggregation]

The analysis of literature and our own data of regulatory peptides influence on the blood coagulation system is presenting. Various natural and synthetic peptides inhibit the activity of thrombin and platelet aggregation. Direct specific inhibitors of thrombin are peptides developed on the base of D-Phe-Pro-Arg sequence. Strong specific inhibitors of the prothrombinase complex factor Xa were isolated from tissues and saliva of the blood-sucking organisms. These inhibitors decrease thrombin generation at the early stage of blood coagulation cascade Anticoagulating peptides from the tick Ornithodoros moubata tissue (TAP), the recombinant rTAP from the saliva glands of tick Ornithodoros savignyi and peptide with even greater anticoagulating activity from saliva glands of fly Glossina morsitans morsitans were isolated and characterised. For complete and reliable suppression of thrombus formation simultaneous administration of thrombin and platelet aggregation inhibitors is necessary. Main terminal stage of platelet aggregation is the interaction of receptor GP IIb/IIIa with adhesive fibrinogen sequence Arg-Pro-Asp (RGD). Peptides derived on the base of this sequence compete with fibrinogen in reaction with platelet receptors. A lot of corresponding peptidomimetics were synthesised, e.g. MK-852, RO-44 and particularly effective compound integrelin. Many direct platelet aggregation inhibitors were found in snake venoms. Recombinant peptide TAP mentioned above exerts both antithrombin and antiaggregation activity. Peptides and peptide mimetics of this type rapidly and irreversibly bound with receptor GP IIb/IIIa. They have short half life time in the blood plasma. Their preference in comparison with other drugs is particularly rapid and strong action. In our experiments it was demonstrated, that simple proline-containing peptides Pro-Gly, Trp-Pro, Pro-Gly-Pro (putative fragments of collagen and elastin) possesses significant antithrombotic and anticoagulant potential in vitro and in in vivo. Perhaps these peptides are members on intrinsic complex of haemostasis regulators.

[The action of ADP ribose on the mechanical and bioelectrical activity of the frog heart]

In the frog isolated heart, cyclic perfusion of ADP-ribose induced a dose-dependent decrease in the heart rate and the contraction force, a decrease in the AP duration as well as in the rate of rise in the sinus node. It also shortened the atrial AP and exerted no significant effect upon multicellular ventricular preparations. In conditions of systemic administration in unanesthetised frogs, the ADP-ribose induced a reversible increase in the heart rate due, probably, to a sympathetic effect.

The effects of analogs of the C-terminal fragment of arginine-vasopressin on the dynamics of development of a conditioned active avoidance response in rats

This paper reports studies of the effects of original analogs of the C-terminal fragment AVP(6-9), D-MPR and D-MPRG, on the development of a conditioned active avoidance response in rats; agents were given intranasally over a wide range of doses. The most effective does of D-MPR was 0.1 microgram/kg, and the most effective dose of D-MPRG was 0.01 microgram/kg. The tri- and tetrapeptide doses were 10 and 100 times smaller than the dose of arginine-vasopressin used in analogous experimental conditions. The tri- and tetrapeptide accelerated development of the active avoidance conditioned response, affecting both formation of the habit and consolidation of the memory trace. The actions of these peptides were mainly on perception processes, i.e., isolation of the concrete stimulus from the environment, and assessment and remembering of its biological significance.

[Improvement of the selective perception and learning with the analog of C-terminal fragment of vasopressin in rats]

New analogue of the AVP(6-9), the D-MPRG was administered intranasally in different doses. The administration improved the process of conditioning. The most efficient dose turned out to be 0/01 mcg/kg. Tetrapeptide administered 1 hour before each learning session and immediately after it accelerated the avoidance conditioning. The peptide effect was more obvious in conditioning with a negative reinforcement. The data obtained suggest that the D-MPRG mostly affects the perception of experimental environment as well as improves the consolidation of memory traces. The peptide was also shown to delay extinction of previously learned skills.

[Induction of long-term depression (with anxiety and fear components) by immunization of rats against pargyline]

The active immunization of albino rats against pargyline (a MAO B inhibitor) induced the formation of antibody to pargyline and results in deep depressive changes and fear. These changes were observed within 6 weeks after the first immunization. Therefore, it opens the possibility to model depression long by exerting the minimum influences. There was also a long-term modulation of craving for alcohol.

[Anxiety-inducing and -inhibiting agents: differential effect of pentagastrins on the white rat behavior]

Parenteral administration of des-BOC-Pentagastrin induced the anxiety and fear manifestations, depressing also explorative behaviour in open field experiments in rats. Intranasal administration evoked similar effects, whereas pentagastrin reduced the anxiety level, increasing explorative behaviour. Pentagastrin and des-BOC-Pentagastrin displayed antagonism at the receptor level.

Immunization against monoamine oxidase slows extinction of a conditioned active escape reflex in rats

Immunization of white rats against bovine plasma monoamine oxidase increased the level of retention of a developed active escape reflex. This phenomenon can serve as a basis for determining the physiological role of bovine plasma monoamine oxidase.