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Biomedical subjects

Z Kleinrok

Publications and source records attributed to Z Kleinrok.

At least 109 records · Page 6Linked to original sources
PubMed1995

The non-competitive AMPA/kainate receptor antagonist, GYKI 52466, potentiates the anticonvulsant activity of conventional antiepileptics.

1-(4-Aminophenyl)-4-methyl-7,8-methylenedioxy-5H-2,3-benzodiazepine hydrochloride (GYKI 52466), up to 5 mg/kg, did not influence the electroconvulsive threshold but potentiated the anticonvulsant activity of valproate, carbamazepine and diphenylhydantoin against maximal electroshock-induced convulsions in mice. No potentiation was observed in the case of phenobarbital. Moreover, this non-NMDA receptor antagonist did not influence the plasma levels of the antiepileptic drugs studied, so a pharmacokinetic interaction, in terms of total and free plasma levels, is not probable. The combined treatment of GYKI 52466 with either carbamazepine or diphenylhydantoin (providing a 50% protection against maximal electroshock) was devoid of significant side effects (motor and long-term memory impairment). Valproate applied at a dose equal to its ED50 caused serious worsening of motor coordination and long-term memory. It is noteworthy that the combined treatment of GYKI 52466 with valproate was superior to valproate alone, as regards adverse effects. The results suggest that concomitant administration of GYKI 52466 with some conventional antiepileptic drugs may offer a novel approach in the treatment of epilepsy.

Animals↗
PubMed1995

Influence of combined treatment with NMDA and non-NMDA receptor antagonists on electroconvulsions in mice.

alpha-Amino-3-hydroxy-5-methyl-isoxazole-4-propionate/kainate (AMPA/kainate) receptor antagonists (at subthreshold doses against electroconvulsions), 1-(4-aminophenyl)-4-methyl-7,8-methylenedioxy-5H-2,3-benzodiazepine (GYKI 52466 at maximally 5 mg/kg) and 2,3-dihydroxy-6-nitro-7-sulfamoylbenzo(F)quinoxaline (NBQX at maximally 20 mg/kg) enhanced the protective effects of NMDA receptor antagonists, MK-801 (dizocilpine) or 2-(2-carboxypiperazine-4-yl)-1-propenyl-1-phosphonic acid (D-CPP-ene), against electroconvulsions. Similarly, MK-801 or D-CPP-ene reduced the ED50 values of both NBQX and GYKI 52466 against maximal electroshock. The adverse effects of D-CPP-ene, evaluated in the chimney and rotorod tests, were potentiated by both GYKI 52466 (2.5 mg/kg) and NBQX (10 mg/kg). Also, D-CPP-ene (0.1 mg/kg) worsened the motor performance of mice pretreated with GYKI 52466 in the rotorod test. Neither MK-801 (0.025 mg/kg) nor D-CPP-ene (0.1 mg/kg) affected the NBQX-induced impairment of motor coordination. Similarly, GYKI 52466 (2.5 mg/kg) or NBQX (10 mg/kg) did not influence the performance of mice treated with MK-801 (0.2 mg/kg). It may be concluded that the blockade of more than one subtype of glutamate receptors leads to a more pronounced anticonvulsive effect when compared with the effect of blockade of an individual receptor subtype. In some cases more efficient seizure protection was not associated with increased adverse effects.

Animals↗
PubMed1995

Influence of BAY k-8644, a calcium channel agonist, on the anticonvulsant activity of conventional anti-epileptics against electroconvulsions in mice.

BAY k-8644, an agonist at the dihydropyridine binding site of the L-type voltage dependent calcium channel, at the dose of 5 mg/kg (s.c.) did not significantly affect the threshold for electroconvulsions, but impaired the protective efficacy of flunarizine (15 and 20 mg/kg, i.p.) in the electroconvulsive test. Interestingly, the calcium channel agonist (at 1 and 5 mg/kg) distinctly diminished the protection offered by conventional anti-epileptic drugs (carbamazepine, diphenylhydantoin and phenobarbital) against maximal electroshock-induced seizures in mice. A pharmacokinetic interaction does not seem to be involved in the effect of BAY k-8644, since total plasma levels of these anti-epileptics (measured by immunofluorescence) were not affected by the calcium channel agonist. The only anti-epileptic drug resistant to BAY k-8644 (up to 5 mg/kg) was valproate, whose ED50 (in mg/kg) was not changed in the presence of the calcium channel agonist. Further, BAY k-8644 (5 mg/kg) did not influence the flunarizine (a calcium channel blocker)-induced potentiation of the protective action of valproate against maximal electroshock-induced convulsions. The calcium channel agonist (5 mg/kg) reversed the flunarizine-induced augmentation of the anticonvulsive activity of carbamazepine. It may be concluded that carbamazepine, diphenylhydantoin and phenobarbital partially exert their anticonvulsive effects via blockade of calcium influx whilst valproate does not seem to. In this context, the flunarizine-induced potentiation of the anticonvulsive activity of valproate is probably independent of calcium channel blockade.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
PubMed1995

Behavioral and biochemical changes after bilateral electrolytic lesions of the red nucleus of rat.

Bilateral electrolytic lesions of the red nucleus (RN) of rat decreased apomorphine-induced stereotypy, increased haloperidol-induced catalepsy, reversed apomorphine-induced hypothermy, decreased spiroperidol-induced hypomotility, and BHT-920-induced yawning and penile erection episodes. Moreover, apomorphine antagonized haloperidol-induced catalepsy in the RN-lesioned group. The lesioned animals revealed depleted levels of dopamine and its metabolites in brain areas as well as serotonin and its metabolite. The brain areas analyzed were pyriform cortex, substantia nigra, striatum, enthorinal cortex, and cerebellum. Based on these results, it is very likely that the RN has a complex role in the behavior of rats as a consequence of dopaminergic-serotoninergic changes in the central nervous system.

Animals↗
PubMed1995

The effect of caerulein-induced acute pancreatitis on the levels of serotonin (5-HT) and 5-hydroxyindoleacetic acid (5-HIAA) in various rat tissues.

The effects of caerulein-induced acute pancreatitis (AP) on the levels of 5-HT and 5-HIAA in pancreas, liver, brain, kidney and different parts of the digestive tract in rats have been studied. The acute pancreatitis was induced by the continuous intravenous infusion of caerulein in the doses of 5 x 10(-6) g/kg/h and 7.5 x 10(-6) g/kg/h for 12 hours, and the 5-HT and 5-HIAA concentrations were determined by the method of Curzon and Green. The changes evoked by caerulein varied qualitatively and quantitatively between organs. The significant decrease of both 5-HT and 5-HIAA was observed in pancreas, liver, brain and kidney while in the stomach there was a significant fall of 5-HT level accompanied by the relevant increase of 5-HIAA level. In the duodenum, an opposite effect was noticed, the level of 5-HT was higher than normal whereas the 5-HIAA level was reduced. The significant decrease of the 5-HT and 5-HIAA levels in pancreas observed in the present study suggests the importance of 5-HT in the development of acute pancreatitis.

Animals↗
PubMed1995

Synthesis and pharmacological study of some derivatives of pyrazolo[4,3-c]pyrido[3,2-c]-1,2-thiazine-5,5-dioxide, a novel heterocyclic ring system.

Starting from pyridothiazines 1 and N-methyl(phenyl)hydrazines isomeric derivatives 2 and 3 of the pyrazolo[4,3-c]pyrido[3,2-e]-1,2-thiazine, a new heterocyclic ring system, have been obtained. The structure of the synthesized compounds was confirmed by spectroscopic and elemental analyses. The results of the preliminary pharmacological study of CNS effects caused by compounds 2 are reported.

Analgesics↗
PubMed1995

Investigations on the synthesis and properties of some N-arylpiperazinylalkyl derivatives of 1,4-dioxo (1,4,5-trioxo)-1,2,3,4-tetra (and 1,2,3,4,5,6-hexa)hydropyrido[3,4-d]pyridazines.

2-(1-Piperidino)- and 2-(4-methyl-1-piperazinyl)-6-methyl-3, 4-pyridinedicarboximides (1,2) react with CH3NH-NH2 yielding 3-methyl derivatives of the corresponding 1,4-dioxo-1,2,3,4-tetrahydropyrido[3,4-d] pyridazines (4,5). The same reaction with 1,6-dimethyl-2-oxo-1,2-dihydro-3,4- pyridinedicarboximide (3) affords 2-methyl derivative of the corresponding 1,4,5-trioxo-1,2,3,4,5,6- hexahydropyrido[3,4-d]pyridazine (8. Compounds 4,5 and 8 were transformed into their N-arylpiperazinylalkyl derivatives (13-18) on two ways. Some of them were active pharmacologically.

Analgesics↗
PubMed1995

The influence of antineoplaston A5 on particular subtypes of central dopaminergic receptors.

A new therapeutic strategy for the treatment of Parkinson's disease (PD) is based on providing trophic support for degenerating dopaminergic (DA) neurons. It can be accomplished by administration of neurotrophic factors, or inducing astrocytes to differentiate and produce such factors. Antineoplaston A5 (A5), which is a naturally-occurring cytodifferentiating agent, may induce astrocytes to undergo normal differetiation, produce neurotrophic factors and alleviate the symptoms of PD. This paper describes studies on the influence of A5 on subtypes of central DA receptors by measuring the potency of haloperidol catalepsy in rats. A5, D1 agonist, and D1 D2 antagonists were given i.p. and D2 agonist s.c. for three consecutive days. Haloperidol catalepsy was measured by the method of Costall and Nylor. The degree of catalepsy was assessed every 30 min for 24 h and statistically evaluated using the Student's t-test. The results confirmed that A5 significantly attenuated catalepsy and stimulates dopamine D2 receptors. It reverses catalepsy induced by haloperidol and D2 antagonists, but increases cataleptogenic activity if given in combination with the D2 agonist. This leads to the conclusion that A5 as a naturally-occurring agent neutralizes both hyper- and hypoactivity of central dopaminergic structures. Besides possible use as an antiparkinsonism agent, A5 may find application in the treatment of other disturbances of dopaminergic transmission.

Animals↗
PubMed1995

The role of dopamine neurotransmission in ethanol dependence development and ethanol withdrawal in rats.

This study was undertaken to evaluate the influence of acute doses of ethanol, chronic ethanol administration and the withdrawal syndrome on central dopaminergic neurotransmission in 700 rats. The ethanol effects were differentiated by their influence on D1 and D2 receptors using following dopaminergic ligands. SKF 38393 (2.5 mg/kg), SCH 23,390 (0.5 mg/kg), pimozide (1 mg/kg), PPHT (2 mg/kg). It was found that ethanol in a low single dose (1.0 g/kg p.o.) increased DA level in rats' brain. In chronic alcoholized rats SKF 38,393 increased the D1 receptor answer in biochemical and behavioural experiments. During the withdrawal period in rats D2 agonist PPHT reversed abstinence symptoms whereas other DA antagonists normalized only some parameters altered by ethanol removal from the diet.

Alcoholism↗
PubMed1995

Synthesis and biological evaluation of 7-azaanalogues of ipsapirone.

The synthesis and preliminary pharmacological evaluation of 4,6-dimethyl-7-azaipsapirone (5c) and related compounds bearing the r-(phenyl, pyridyl, pyrimidinyl)-1-piperazinyl moiety linked through a butyl or ethoxyethyl chain with the isothiazolo[5,4-b]pyridine system, are described.

Amphetamine↗
PubMed1994

Influence of a Ca2+ channel agonist, Bay k-8644, on the anticonvulsant activity of NMDA and non-NMDA receptor antagonists.

Bay k-8644 (methyl-1,4-dihydro-2,6-dimethyl-3-nitro-4-(2-trifluoro- methylphenyl)-pyridine-5-carboxylate) (a Ca2+ channel agonist of the dihydropyridine class) at 5 mg/kg (s.c.) impaired the anticonvulsant activities of two competitive NMDA receptor antagonists, CGP 37849 (D,L-(E)-2-amino-4-methyl-5-phosphono-3-pentenoic acid) and D-CPP-ene (3-(2-carboxypiperazine-4-yl)-1-propenyl-1-phosphonic acid) (given i.p.), against electroconvulsions. In contrast, the Ca2+ channel agonist did not affect the protection afforded by the AMPA receptor antagonists, NBQX (2,3-dihydroxy-6-nitro-7-sulfamoylbenzo(F)quinoxaline) and GYKI 52466 (1-(4-aminophenyl)-4-methyl-7,8-methylendioxy-5-2,3-benzodiazepine ), or by a non-competitive NMDA receptor antagonist, MK-801 (dizocilpine), all being injected i.p. It may be concluded that the anticonvulsive activity of competitive NMDA receptor antagonists can be impaired by Ca2+ ion influx.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
PubMed1994

The NMDA antagonist procyclidine, but not ifenprodil, enhances the protective efficacy of common antiepileptics against maximal electroshock-induced seizures in mice.

Procyclidine (up to 20 mg/kg i.p.) did not influence the electroconvulsive threshold per se, but when given in a dose of 10 mg/kg, it potentiated the protective activity of carbamazepine, diphenylhydantoin, phenobarbital and valproate, and in a dose of 20 mg/kg, that of diazepam against maximal electroshock-induced convulsions in mice. Ifenprodil increased the threshold for electroconvulsions when applied at 20 and 40 mg/kg (i.p.), but surprisingly, when combined with all antiepileptics tested, it did not influence their anticonvulsant actions. The chimney test in mice revealed, that application of procyclidine at 10 mg/kg together with phenobarbital and valproate, and procyclidine at 20 mg/kg with diazepam resulted in motor impairment. However, when procyclidine was applied at 10 mg/kg together with carbamazepine or diphenylhydantoin, no motor impairment was noted. The combined treatment of procyclidine (10 mg/kg) with carbamazepine, diphenylhydantoin, phenobarbital or valproate, as well as procyclidine (20 mg/kg) with diazepam caused significant worsening of long-term memory. Finally, procyclidine did not alter the total plasma levels of carbamazepine, diazepam, diphenylhydantoin, phenobarbital and valproate. It may be concluded that not all agents interfering with NMDA receptor complex-mediated events lead to the potentiation of the anticonvulsant activity of antiepileptic drugs.

Animals↗
PubMed1994

The competitive NMDA antagonist, D-CPP-ene, potentiates the anticonvulsant activity of conventional antiepileptics against maximal electroshock-induced seizures in mice.

D-CPP-ene[3-(2-carboxy-piperazine-4-yl)-1-propenyl-1-phosphonic acid; a competitive antagonist of N-methyl-D-aspartic acid] in a dose of 2 mg/kg (i.p.) significantly increased the threshold for electroconvulsions. When given in a dose half that affecting the electroconvulsive threshold, D-CPP-ene potentiated the anticonvulsant activity of carbamazepine, diazepam, diphenylhydantoin, phenobarbital and valproate against maximal electroshock (50 mA)-induced seizures in mice. However, this NMDA antagonist did not influence the plasma levels of the antiepileptic drugs studied, so a pharmacokinetic interaction, in terms of total plasma levels at least, is not probable. The chimney test and retention test in mice revealed that the combined treatment of D-CPP-ene at 1.0 mg/kg (i.p.) with either diazepam, diphenylhydantoin, phenobarbital or valproate (providing a 50% protection against maximal electroshock convulsions) resulted in motor impairment and caused impairment of long-term memory. On the other hand, a combination of D-CPP-ene and carbamazepine was devoid of adverse effects. It can be concluded that the potential utility of D-CPP-ene in combination with conventional antiepileptic drugs does not seem promising, except for carbamazepine.

Animals↗
PubMed1994

Influence of chronic aminophylline on antielectroshock activity of diazepam and aminophylline-induced convulsions in mice.

The effects of chronic administration of aminophylline (AMPH; 50 mg/kg, twice daily for 14 consecutive days) were studied on both antielectroshock efficacy of diazepam (DZP) and convulsive activity of AMPH in mice. AMPH injected acutely at a dose of 50 mg/kg significantly reduced anticonvulsant action of DZP elevating ED50 from 10.9 (control) to 15.9 mg/kg (p < 0.01). After the administration of AMPH for 3 days, ED50 value was still higher compared with control. Chronic treatment with AMPH resulted in further increase of ED50 of DZP, which was 20.2 mg/kg, and this elevation was significant not only when compared with saline-treated animals, but also with acute and 3-day administration of the xanthine (p < 0.01, 0.05, and 0.001, respectively). Therefore, no tolerance to this AMPH-mediated effect was found, and even an enhancing influence was observed. On the other hand, chronic treatment with AMPH decreased convulsive activity of AMPH elevating ED50 for induction of clonic seizures from 218 to 252 mg/kg (p < 0.01). The remaining seizure parameters were unaffected. Furthermore, in both cases pharmacokinetic interactions were excluded, at least in terms of total plasma levels of the drugs. The results suggest that the mechanisms governing AMPH-induced reversal of the anticonvulsant efficacy of DZP qualitatively differ from those underlying AMPH-induced convulsions. Moreover, these data support the claim that AMPH should be avoided in patients suffering from different types of epilepsy.

Aminophylline↗
PubMed1994

The influence of antineoplaston A5 on the central dopaminergic structures.

Antineoplastons are naturally occurring cytodifferentiating agents. Chemically, antineoplastons are medium and small sized peptides, amino acid derivatives and organic acids which exist in blood, tissues and urine. In clinical trials in advanced cancer, in addition to the anticancer activity it was observed that patients suffering from both cancer and Parkinson's disease exhibited marked improvement in parkinsonian symtomatology when treated with antineoplaston A5. The present study was designed to analyse the influence of A5 on central dopaminergic structures. Mice and rats were given A5 intraperitoneally at three different dosage levels. Experiments conducted included spontaneous locomotor activity, amphetamine-induced yawning and erections, catalepsy, the effect on the level and utilization of noradrenaline and dopamine in the brain and the influence of prolonged and chronic treatment on the haloperidol-induced catalepsy. It has been demonstrated that A5 stimulates the central dopaminergic receptors. It diminishes the cataleptic response to haloperidol and enhances the incidence of apomorphine-induced yawning. Biochemical studies demonstrated increased concentration of dopamine and noradrenaline in the brain and diminished utilization of both catecholamines.

Amphetamine↗
PubMed1994

Synthesis and pharmacological properties of some new 3-(2-N,N-dialkylaminoethyl)-pyrido [2,3-d]-pyrymidin-4-ones.

The following new derivatives of pyrido [2,3-d]-pyrimidin-4(3H)-one were synthesized: 3-(2-N,N-dimethylaminoethyl), 3-(2-N-pyrolidynylethyl), 3-(2-piperidinylethyl) and 3-(2-N-morpholidinylethyl). Their chemical structures were confirmed by MS, IR and 1H NMR spectroscopic data. Newly synthesized compounds were investigated pharmacologically for their central properties in mice and rats. It was shown that compound [III] showed anxiolytic action in the four-plate test and two compounds produced analgesic effects in mice.

Analgesics↗