Behavioral effects of original tetrapeptide, an analog of N-terminal nociceptin fragment.

The study examined the effect of an analog to N-terminal nociceptin fragment AcOH×Phe-Gly-Gly-Phe-NH(2) on the behavior of albino rats. This tetrapeptide (5 μg/kg intraperitoneally) significantly enhanced motor and exploratory activity in mature rats and in 42-day pups and produced opposite effects in 21-day rat pups, which attests to the complex dynamics of maturation of nervous structures involved in the realization of nociceptin action.

[Myelopeptide MP-5 and fluorescent derivatives: synthesis and biological activity].

The Val-Val-Tyr-Pro-Asp bone marrow peptide (MP-5) and an analogue (MP-5-Lys) were synthesized. Fluorescent derivatives, Ftc-MP-5 and MP-5-Lys(Ftc), were prepared. The biological activity of MP-5 and MP-5-Lys was studied in vitro and in vivo.

[The pharmacological modulation of group behavior and biorhythms in the dynamics of a chronic experiment].

Cyclic daily experiments were conducted using the standard method of free behavior of animals in an "open field" (Opto-Varimex, USA) with by the hour recording of locomotor parameters. The neuromodulating activity of 124 pharmacological agents was compared according to the size and duration of their stimulating or depressant effect.

Localization of a fibrin polymerization site complementary to Gly-His-Arg sequence.

Dansyl-labeled tetrapeptide Gly-His-Arg-Pro which mimics the central fibrin polymerization site was used to investigate its binding to a number of fibrinogen fragments containing different numbers of domains. The tetrapeptide was found to bind to fragments DH(95 kDa), DL(82 kDa) and DY(63 kDa) but not to the TSD(28 kDa) fragment. The DY fragment differs from the TSD by the presence of beta and beta C domains.

[The effect of regulatory peptides on water absorption in the large intestine of the frog].

Preparation of isolated large intestine of the frog was filled with Ringer's solution diluted with distilled water (1:5) and was placed into the glass with normal Ringer's solution. The preparation was weighed within every 30 min and the osmotic permeability was determined for water of the mucous and serous layers of the intestine. Then one of the peptides was added to Ringer's solution and the experiment continued.

[Minor peptides of animal proteins as antibiotics and possible factors of nonspecific immunity].

Screening of more than twenty short synthetic peptides characteristic of different proteins has revealed antimicrobial activity of the KRFAE peptide--from human preproenkephalin A against gram-negative bacteria. Modification of the peptide structure by means of administration of d-amino acids has permitted obtaining dKRFdLE analogue with the expressed and stable antimicrobial activity in vitro when growing bacteria on the minimum glucose-mineral medium. Changes and rearrangements of aminoacids in the dKRFdLE peptide in the second, third and fourth positions sharply decreased anti-microbial activity.

[Analysis of new opiate-like peptides using a radioreceptor method].

A screening of new synthetic opioid-like peptides has been carried out by the radioreceptor assay using selective labeled ligands to mu-, delta- and gamma-opioid receptors of the rat brain membranes. With this aim peptides from sequences of the following proteins were used: kapporphin-Tyr-Ser-Phe-Gly-Gly and its analogues-Tyr-Ser-Phe-Gly-Gly-NH2, Tyr-D-Ser-Phe-Gly-Gly, Tyr-D-Ser-Phe-Gly-Gly-NH2, myelorphin-Phe-Gly-Tyr-Gly-Gly, interenkephalin B-Arg-Arg-Gln-Phe-Lys and chimeric peptide IEPhBin 1-Tyr-Gly-Gly-Phe-Leu-Arg-Pro-Tyr-Ile-Leu consisting of leu-enkephalin and pentaneurotensin. It has been found that myelorphin has a prevalent affinity to mu-receptor, while the kapporphin analogues both to mu- and delta-receptors.

[Highly active analogs of opiate-like peptides historphin and kapporphin].

Analgetic activity of analogues of new opioid peptides historphine Tyr-Gly-Phe-Gly-Gly and capporphine Tyr-Ser-Phe-Gly-Gly was studied. Analogues of historphine Tyr-D-Ala-Phe-Gly-Gly and of capporphine Tyr-D-Ser-Phe-Gly-Gly exceeded 10(3)-fold the Leu-encephaline efficiency using a tail-jerk test and their derivatives containing amide group in the C-end position--10(4)-fold. All the four analogues increased the resistance period in the heat plate test.

[Opiate-like peptides with primary structure different from that of enkephalins].

Some new opiate-like peptides originating from opioid peptide precursors, dinorphine, histone H2b, major myeline protein, natriuretic atriopeptide and from the immunomodulating protein splenin whose primary structure differs essentially from that of enkephalins are described. Being intracysternally injected to mice, all the peptides under study caused a naloxone-sensitive analgetic effect as could be judged from the tail pinch tests. The effects of some opiate-like peptides were much stronger than that of leu-enkephalin.

[The role of complementary E2 and D2 centers in the reaction between fibrin and fibrinogen].

The effect of fibrinogen on the two steps of polymerization of two fibrin forms differing in the set of polymerization sites (fibrin-desAA and fibrin-desAABB) was studied. It was shown that fibrinogen inhibited the protofibril growth and fibril formation at the stage of lateral aggregation more effectively with fibrin-desAABB than with fibrin desAA. When the fibrinogen D2-site was blocked by tetrapeptide Gly-His-Arg-Pro, the key structure of the E2-site, the inhibitory activity of fibrinogen diminished.

[Spike activity of neurons of the ventromedial hypothalamus of the rabbit in response to cholecystokinin application to the cornea].

Microapplication to the rabbit eye cornea of the [Glu26] analogue of nonsulphated C-terminal octapeptide cholecystokinin reduced 2-5-fold the firing rate of the ventromedial hypothalamus neurons whereas [Glu26, 32] induced a 2-3-fold increase of the firing rate. Contralateral application increased 1.2-2.

[Effect of somatostatin on the neurosecretory cells of the hypothalamic paraventricular nucleus and argentaffin cells of the antral part of the rat stomach].

Administration of somatostatin induced changes of functional activity in all the central and peripheral structures under study. Neuronal activity in the paraventricular nucleus decreased by the 3rd and 15th min after somatostatin injection whereas by the 20th min the firing rate increased. Amount of argenaffin cells was sharply reduced, at that, between the 4th and 15th min which suggested an active release of enterochromaffin cell granules into the blood.

[Effect of natural neurotensin and its analog on gastric secretion and levels of various peptides in dog blood].

I.v. administration of neurotensin and its analogue DTch1I--neurotensin considerably decreased stomach secretion induced with pentagastrin but did not suppress stomach secretion induced with histamine, neither a microapplication of 10 micrograms in 3 microliter of neurotensin affected the secretion whereas the dose 50 micrograms in 3 microliter decreased both volume and acidity of the juice.

There are receptors for neurotensin in the caudate nucleus and posterior hypothalamus.

It was established in chronic experiments on dogs that the introduction of neurotensin in a dose of 3 or 10 micrograms in 1.5 microliters into the caudate nucleus changes the parameters of the conditioned and unconditioned food reflexes: a 31% shortening of the latent period and a 56% increase in the magnitude of the reflex. Microapplication of neurotensin in the same doses in the posterior region of the hypothalamus enhanced the secretory function of the gland caused by the introduction of histamine.

[Effect of neurotensin and (DTr11)-neurotensin on the secretory function of the pancreas].

In chronic experiments on dogs, administration of neurotensin into cerebral structures (hypothalamus, caudate nucleus) or into the blood flow exerted the same effect: enhancement of the pancreas secretory function, depending on the dosage of the i.v. administration.