Study on the neurotropic activity of the products of Semax enzymatic degradation.
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Adrenocorticotropic Hormone↗
Biomedical subjects
L A Andreeva
Publications and source records attributed to L A Andreeva.
[Changes in beta-casomorphine-7 effect on behavior of albino rat pups in postnatal development].
The analgetic effect of heptapeptide beta-casomorphine-7 in newborn albino rats (20 mg/kg, i.p.) was recorded already 14 days after birth in the "hot plate" test. The first signs of a possible influence of the peptide on motor activity were observed only at the age of 28 days. They are expressed in impairment of motor coordination and change in locomotion level ("Opto-Varimex" test). The obtained evidence probably reflect the processes of discrete maturation of different components of the opioid system of the rat brain.
Analgesics, Opioid↗
[Effect of dermorphin analogs on thermoregulation of rats under various thermal conditions].
We studied the influence of dermorphin (dermorphin) analogs with stereochemical modification of the amino acid residue proline in position 6 (Pro6), Tyr-D-Ala-Phe-Gly-Tyr-Hyp-Ser-NH2, Tyr-D-Ala-Phe-Gly-Tyr-[D-Pro]-Ser-NH2, Tyr-D-Ala-Phe-Gly-Tyr-[dehydro-Pro]-Ser-NH2, and Tyr-D-Ala-Phe-Gly-Tyr-[D-dehydro-Pro]-Ser-NH2, after their intraperitoneal injection at 0.5 mg/kg dose in the cold (4-7 degrees C), thermoneutral (27-28 degrees C), and hot (31-33 degrees C) environment. Stereochemical modifications of amino acid residue Pro6 proved to induce specific changes in the thermoregulatory effect of the peptide. Substitution of DPro6 for Pro6 has the most dramatic consequences: it considerably attenuates the thermoregulatory effect of dermorphin in the cold environment, cancels it in the hot environment, and inverts the dermorphin-specific thermoregulatory response in thermoneutral conditions. The data obtained indicate the important role of Pro6 residue in realization of this physiological activity of dermorphins.
Animals↗
[Effect of structural changes of Pro6 in dermorphin molecule on its antinociceptive activity].
We studied effect of dermorphin (H-Tyr-DAla-Phe-Gly-Tyr-Pro-Ser-NH2) and its analogs with modified amino acid residue proline in position 6, H-Tyr-DAla-Phe-Gly-Tyr-[DPro]-Ser-NH2, H-Tyr-DAla-Phe-Gly-Tyr-[dehydro-Pro]-Ser-NH2, and H-Tyr-DAla-Phe-Gly-Tyr-[D-dehydro-Pro]-Ser-NH2, on nociception in the tail-flick and hot plate tests after intraperitoneal injection. Replacement of LPro with the stereoisomer DPro as well as Pro dehydration (LdHPro) was shown to increase antinociceptive activity. Replacement of LdHPro with DdHPro cancelled the activity in the tail-flick test. All three dermorphin analogs retained antinociceptive activity in the hot plate test; however, the effect of dermorphin was more pronounced.
Analgesics↗
[Characteristics of force-frequency relations in the myocardium of the squirrel Citellus undulatus].
The force-frequency relationship (FFR) in papillary muscles of the heart of active ground squirrel in different seasons was studied. For comparison, similar preparations from rat and rabbit were used. It was shown that the FFR of papillary muscles of active ground squirrel undergo significant seasonal changes. In summer and a part of autumn squirrels, a negative staircase (a decrease in the isometric force with increasing stimulation frequency) similar to that in adult rat was revealed. The FFR of the majority of autumn, winter and spring squirrels were polyphasic and contained both positive and negative components. Changes in the force in response to the introduction of pauses at a constant stimulation frequency were recorded. Two types of the post-rest recovery pattern were revealed in the myocardium of ground squirrels. For frequencies range with the negative direction of FFR, a typical pattern of rest-potentiation similar to that in rat papillary muscles was observed. The amplitude of the first post-rest contraction (F1) was usually higher than that of the preceding steady-state contraction. In papillary muscles of autumn animals the F1 value was greater that in summer, which suggests an enhanced release of Ca2+ from the sarcoplasmic reticulum. There was no post-rest potentiation in the range of frequencies with positive direction of FFR, and the post-rest recovery pattern in these cases was principally different from those of rat and rabbit preparations. It was proposed that seasonal differences of the FFR of active ground squirrel heart are associated with changes in the ratio of activities of the calcium-transporting system in the hibernation period.
Animals↗
[Behavioural effects of beta-casomorphin-7 in its intranasal administration].
Intranasally administrated natural opioid peptide beta-casomorphin-7 (doses 0.001, 0.005, 0.02, and 0.1 mg/kg) was shown to produce alterations in behavior of male albino rats. The anxiolytic effect of the peptide tested in two "open field" modifications was most pronounced. Besides, two higher doses of promoted learning under conditions of negative reinforcement. The beta-casomorphin-7 effects on pain sensitivity and locomotion were insignificant. The obtained results only in part coincide with the effects of intraperitoneal peptide injection described earlier. This suggests that the specific effects of beta-casomorphin-7 considerably depend on the way of its penetration into a body; in case of intranasal administration they are apparently determined by primarily influence of the peptide on hypothalamic structures.
Administration, Intranasal↗
[Pharmacokinetics of glyprolines (PGP) upon intragastric administration].
The pharmacokinetics of glyprolines upon intragastric administration in rats was studied by monitoring the content of tritium-labeled PGP in the blood plasma and protein, in organs (for 5 h), and urine (for 8 h). The maximum radioactivity (2.25% of the introduced level) in the blood plasma was observed 15 min after administration of [3H]-PGP. Then, the radioactivity level gradually decreased, but even in 5 h it exceeded 1%. In contrast, the radioactivity of deposited protein gradually increased. The content of labeled PGP and its metabolites in organs was much lower than in the blood. The radioactivity 15 min after administration was as follows (%): intestine, 1.4; stomach, 0.1; liver, 0.09; brain, heart, and kidney, < 0.05; in 5 h, the radioactivity level was below 0.02% (except for intestine, where it was still greater than 0.1%). No labeled PGP or its metabolites were found in the urine during the 8-h period of observations. It is not excluded that glyprolines introduced with PGP are involved in the synthesis of new peptides and proteins, including collagen.
Animals↗
[Thermoregulatory activity of dermorphin fragments].
We studied the effect of C-terminal truncation of the dermorphin (DM) molecule and analogs of its N-terminal tetrapeptide, [DOrn2]-DM(1-4), [DArg2]-DM(1-4), [DAla4]-DM(1-4), [DArg2, DAla4]-DM(1-4), Arg-DM(1-4), Arg-[DArg2]-DM(1-4), Arg-[DAla4]-DM(1-4), and Arg-[DArg2, DAla4]-DM(1-4), on the functional status of the thermoregulation system in rats at different ambient temperatures. For the first time, we demonstrate that the N-terminal tetrapeptide is the minimal fragment with the hypothermic effect. Only the N-terminal octapeptide exerted the vasomotor effect. Amino acid substitutions in the tetrapeptide affected its hypothermic effect. [DArg2]-DM(1-4) and [DArg2, DAla4]-DM(1-4) had the greatest effect. Addition of Arg to the N-terminus of DM(1-4) analogs changed their thermoregulatory activity. The greatest thermoregulatory effect was observed for Arg-[DArg2]-DM(1-4) and Arg-[DArg2, DAla4]-DM(1-4).
Analgesics, Opioid↗
[An experimental substantiation for using the "Semax" neuroprotector in the treatment of optic-nerve diseases].
In order to substantiate the feasibility of using the "Semax" neuroprotector in the treatment of optic-nerve diseases its pharmacokinetics in the intranasal administration was studied in experiments with rats; besides, the physical-and-chemical properties of "Semax" were investigated to define the preparation's stability and mobility in the electric field. A series of experiments, involving a tritium-marked "Semax", showed that the peptide actively penetrates into the brain and eyes of experimental animals after its intranasal administration. It was established, within a study aimed at determining the electrophoretic activity and stability of "Semax" in the electric field, that the preparation does not disintegrate in the electric field, it posses the electrophoretic mobility and moves, in the electric field, from plus to minus; therefore, the "Semax" solution must be fed from anode while making the electrophoresis procedure.
Administration, Intranasal↗
[Study of thermoregulatory activity of a fragment of natural dermorphin precursor Arg-dermorphin and its analogs].
We studied the effect of a fragment of natural dermorphin (DM) precursor Arg-DM and its analogs (Pro-DM, 4Amino-Pro-DM, Mike et-DM, Kre-DM, Arg-[DArg2]-DM, and Arg-[DAla4]-DM after intraperitoneal administration on the functional status of the thermoregulation system in rats. The obtained data demonstrated that the hypothermic and vasomotor effects of Arg-DM were temperature-dependent and had the same pattern as DM (Emel'yanova et al., 1996). In the thermoneutral and room environment, the peptide induced a two-phase vascular response. The first phase was vasodilation; it was twice as strong as for DM and was not removed by naloxone pretreatment. The second phase was vasoconstriction; it was blocked by naloxone. Replacement of Arg with 4Amino-Pro, Met, and Kre as well as DAla2 to DArg2 or Gly4 to DAla4 replacements in the Arg-DM molecule affected the thermoregulatory activity of the peptide. For instance, only the vasodilation response was observed for Arg-[DAla2]-DM and Arg-[DAla4]-DM while only the vasoconstriction response was observed for 4Amino-Pro-DM.
Amino Acid Substitution↗
[Long-lasting behavioral effects of chronic neonatal treatment with ACTH (4-10) analogue semax in white rat pups].
It is well known that ACTH/MSH-like peptides (melanocortins) have neurotrophic and neuroprotective effects on the central and peripheral nervous systems in the early postnatal life. The aim of present work was to study consequences of the ACTH (4-10) analogue Semax influence on the developing brain. The work was carried out in white rat pups. The peptide (0.05 mg/kg, i/p) was injected daily on the 8th-21st postnatal days. Delayed long-lasting effects of such treatment on animal behavior were revealed. At the age of four to eight weeks, Semax-treated rats displayed elevated exploratory activity, decreased anxiety level and improved passive avoidance conditioning. The results suggest that neonatal Semax administration modulates the development of the central nervous system.
Adrenocorticotropic Hormone↗
[Analgesic activity of dermorphin and its proline analogs].
Dermorphin (Tyr-D-Ala-Phe-Gly-Tyr-Pro-Ser-NH2; DM) and its analogs obtained via stereochemical transformation of L-Pro6 to D-Pro6 peptide in DM ([Dpro6]DM) and via dehydration of L-Pro6 peptide ([dHPro6]DM) were characterized with respect to the analgesic activity in rats tested under conditions corresponding to various levels of pain sensitivity organization. The drugs were introduced by intraperitoneal injections in various doses (0.1, 1.0, and 10 mg/kg). In the case of acetic-acid induced convulsions (writhing), DM and [Dpro6]DM produced analgesic action in the minimum dose, while the analogous effect of [dHPro6]DM was observed only in greater doses. In the tail-clamp (Haffner) test, DM and [Dpro6]DM also inhibited nociception while the latter compound was ineffective. In the grid-shock test, [Dpro6]DM showed a higher activity than [dHPro6]DM, whereas DM did not produce analgesic action. Thus, all the studied peptides exhibit pronounced analgesic activity, and the replacement of L-Pro6 in DM by its stereomer D-Pro is more effective than the substitution of dHPro6.
Amino Acid Substitution↗
[Corticoliberin fragment CRF4-6 modifies rat behavior in opposite ways under stressing and non-stressing conditions].
The effects of tripeptide corticoliberin fragment CRF4-6 (icv; 6, 30, and 150 nmol/head) on behaviour of rats were investigated under non-stressing and stressing conditions. CRF4-6 activated rat behaviour under non-stressing conditions (home cage): the duration of locomotion and exploratory behaviour was increased whereas the duration of passive behaviour and sleep was decreased. On the other hand, CRF4-6 suppressed the rat exploratory behaviour under stressing conditions (elevated plus-maze): the duration of non-exploratory behaviour was increased; numbers of rearings and leanings out to open arms were reduced. All observed effects of the tripeptide CRF4-6 were dose-dependent. Behavioural effects of the tripeptide were similar to the well-known action of the whole corticoliberin molecule. Therefore we suggest that CRF4-6 is located in the active part of CRF or it can be a physiologically active corticoliberin derivative.
Animals↗
[Comparative study of the physical dependence on proline analog of dermorphin and morphine].
On the model of acute physical dependence, naloxone treatment of animals dependent on D-Pro6 peptide ([D-Pro6]DM) (a demorphin analog) led to tremor, shaking, convulsions, and rare jumps typical of morphine-dependent animals. The variety and intensity of reactions depended on the naloxone dose and the interval between naloxone and peptide injections. In the state of reject syndrome upon peptide and morphine subchronic treatments according to identical schedules, the symptoms in [D-Pro6]DM dependent animals were much less pronounced than in morphine-dependent ones.
Animals↗
[Effect of modification of the N-terminal region of molecule on the expression of neotropic effect of semax analogues].
A comparative study of neotropic activity of semax (MEHFPGP), an analogue of the 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 (alimentary) 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 neotropic effect of the peptide was retained. The substitution of methionine with tryptophan or serine resulted in a decrease in the neotropic activity. The substitution of methionine with glycine, threonine, or alanine caused a complete loss of the neotropic activity of the peptide. Therefore, the amino acid residue located at position 1 of the heptapeptide analogue semax, plays a key role in retaining the neotropic effects of the peptide and determines the degree of their expression.
Adrenocorticotropic Hormone↗
[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 ACTH4-10 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.
Adrenocorticotropic Hormone↗
[Evenly tritium-labeled peptides and their in vivo and in vitro biodegradation].
Biologically active peptides evenly labeled with tritium were used for studying the in vitro and in vivo biodegradation of the peptides. Tritium-labeled peptides with a specific radioactivity of 50-150 Ci/mmol were obtained by high temperature solid phase catalytic isotope exchange (HSCIE) with spillover tritium. The distribution of the isotope label among all amino acid residues of these peptides allows the simultaneous determination of practically all possible products of their enzymatic hydrolysis. The developed analytical method includes extraction of tritium-labeled peptides from organism tissues and chromatographic isolation of individual labeled peptides from the mixture of degradation products. The concentrations of a peptide under study and the products of its biodegradation were calculated from the results of liquid scintillation counting. This approach was used for studying the pathways of biodegradation of the heptapeptide TKPRPGP (Selank) and the tripeptide PGP in blood plasma. The pharmacokinetics of Selank, an anxiolytic peptide, was also studied in brain tissues using the intranasal in vivo administration of this peptide. The concentrations of labeled peptides were determined, and the pentapeptide TKPRP, tripeptide TKP, and dipeptides RP and GP were shown to be the major products of Selank biodegradation. The study of the biodegradation of the heptapeptide MEHFPGP (Semax) in the presence of nerve cells showed that the major products of its biodegradation are the pentapeptide HFPGP and tripeptide PGP. The enkephalinase activity of blood plasma was studied with the use of evenly tritium-labeled [Leu]enkephalin. A high inhibitory effect of Semax on blood plasma enkephalinases was shown to arise from its action on aminopeptidases. The method, based on the use of evenly tritium-labeled peptides, allows the determination of peptide concentrations and the activity of enzymes involved in their degradation on a tg scale of biological samples both in vitro and in vivo.
Adrenocorticotropic Hormone↗
[The effect of an SHF field on the dopamine-dependent behavior of rats].
A study was made of the influence of SHF radiation (8 mW/cm2, carrier frequency 0.88 Hz, modulation frequency 16 Hz) on rotation of rats induced by apomorphine. A single exposure within an hour was shown to inhibit apomorphine-induced rotation by 21%. Daily one-hour exposure within 5 days caused a more pronounced inhibition of test-response. Different individual sensitivity to SHF radiation was noted.
Animals↗