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Biomedical subjects

Z Kleinrok

Publications and source records attributed to Z Kleinrok.

At least 325 records · Page 18Linked to original sources
PubMedDate not supplied

Effect of adenosine A1 and A2 receptor stimulation on hypoxia-induced convulsions in adult mice.

Clinical observations indicate that seizures induced by hypoxia are common kind of convulsive activity in both infants and elderly patients. The occurrence of seizure episode during hypoxia is important risk factor of epilepsy development in the future. Experimental hypoxia was obtained by exposure of adult (20-23 g) Albino Swiss mice to spontaneous breathing in gas mixture composed of 5% oxygen and 95% nitrogen. The latency time to convulsive activity was determined. Single sublethal episode of seizures induced by hypoxia (HS) resulted in higher susceptibility to pentetrazol (PTZ), bicuculline (BCC), N-methyl-D-aspartic acid (NMDA) but not in electrically induced convulsions. Adenosine A1 receptor agonist, R(-)N6-(2-phenyl-isopropyl)adenosine (R-PIA) (0.01; 0.05; 0.1 mg/kg, i.p.) prolonged the latency to HS-induced convulsions. A1 receptor antagonist, 8-cyclopentyltheophylline (CPT), reversed the protective action of R-PIA. A2 receptor agonist, N(6)-[2-(3,5-dimethoxyphenyl)-2-(2-methylphenyl)]ethyladenosine (DPMA), only at the highest dose (5 mg/kg i.p.) prolonged the latency time to convulsive activity. This effect was only partially reversed by A2 antagonist 3,7-dimethyl-1-propargylxanthine (DMPX). Administered immediately after episode of HS R-PIA diminished the higher susceptibility to PTZ, BCC, NMDA at 3rd day after HS, while DPMA appeared to be ineffective. These results confirm the important role of adenosine A1 receptor agonist in protection against acute and chronic epileptogenic effect of hypoxia. The role of adenosine A2 receptors seems to be of minor importance.

Adenosine↗
PubMedDate not supplied

Interaction of GYKI 52466, a selective non-competitive antagonist of AMPA/kainate receptors, with conventional antiepileptic drugs in amygdala-kindled seizures in rats.

GYKI 52466 [1,4-aminophenyl)-4-methyl-7,8-methylenedioxy-5H-2,3-benzodiazepine], a non-competitive AMPA/kainate receptor antagonist, administered i.p. at the dose of 5 mg/kg, exerted a significant anticonvulsant effect, as it decreased seizure and afterdischarge durations, being ineffective at 2 mg/kg. Subsequently, GYKI 52466 (2 mg/kg) was combined with antiepileptic drugs at doses ineffective in fully kindled rats. Co-administration of GYKI 52466 with clonazepam (0.003 mg/kg i.p.) resulted in a significant reduction of seizure severity (by 20%), seizure duration (by 31%) and afterdischarge duration (by 24%). Co-injection of GYKI 52466 with valproate (75 mg/kg i.p.) also resulted in the respective 8%, 16%, and 17% reductions of the three studied seizure parameters. No protection was observed when GYKI 52466 was co-administered with carbamazepine (20 mg/kg i.p.), phenobarbital (20 mg/kg i.p.), or diphenylhydantoin (40 mg/kg i.p.). Combinations of GYKI 524662 with antiepileptic drugs did not cause any significant motor (rotarod test) or long-term memory deficits (passive avoidance task). Only GYKI 52466 administered alone at 5 mg/kg, caused a significant impairment of retention in amygdala-kindled rats. The interaction at a pharmacokinetic level, at least in case of the combination of GYKI 52466 with valproate, can be excluded because GYKI 52466 did not interfere with the free plasma level of valproate. These results give further support to the idea of a potential clinical benefits of the combined treatment of AMPA/kainate receptor antagonists with some antiepileptic drugs.

Amygdala↗
PubMedDate not supplied

Comparison of central effects of noradrenaline and dopamine injected into the lateral brain ventricle in rats.

Noradrenaline and dopamine injected into the lateral brain ventricle exerted a significant effect on the behavior of rats. Both amines caused a slight rise in the basic locomotor activity which was significantly increased in the animals with inhibited monoamine oxidase activity. Besides that, they suppressed the behavior of rats in the open-field test, inhibited the conditioned avoidance response, decreased body temperature and increased amphetamine-induced motor hyperactivity. Noradrenaline, in contrast to dopamine, changed the intensity of amphetamine-induced stereotypy and prolonged the action of hypnotics. The central action of both catecholamines (in higher doses especially) seemed to have a biphasic course: in the first phase after administration depression was observed which was more pronounced after noradrenaline administration, in the second phase a stimulating effect b

Amphetamine↗
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Synthesis and properties of tetra(hexa)hydropyrazolo [1,2-a]pyrido[3,4-d]pyridazine derivatives.

The synthesis of tetra(hexa)hydropyrazolo[1,2-a]pyrido[3,4-d]pyridazine derivatives (14-21) and the results of pharmacological screening are described in this paper. All compounds tested were non-toxic and showed a significant analgesic action. The analgesic effects were associated with the suppression of the spontaneous locomotor activity. Furthermore most of the synthesized compounds displayed a weak antimycobacterial action in the preliminary screening.

Analgesics, Non-Narcotic↗
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Synthesis and some central pharmacological properties of new derivatives of 2,3-dihydroimidazo[1,2-a]pyrimidine-6-carboxylic acid.

Twenty one derivatives of 2,3-dihydroimidazo[1,2-a]pyrimidine-6-carboxylic acid (6 n-butyl amides and 15 free acids) bearing the aromatic ring in position 1 or 2 were obtained. They were synthesized by aminolysis or hydrolysis of respective ethyl esters. Pharmacological studies on the central action of eight compounds 1, 2, 4, 5, 7, 8, 9 and 10 were carried out on mice and rats. The most active compounds, producing sedation and hypothermia, and 1, 2 and 5. The compounds decreased amphetamine-induced hyperactivity. Besides, compound 2 exerted analgesic effect in mice.

Animals↗
PubMedDate not supplied

Basic central pharmacological properties of thiophosphoric acid alkaloid derivatives from Chelidonium majus L.

The effects of thiophosphoric acid alkaloid derivatives from Chelidonium majus L. (Ukrain, UKSR-222) on the central nervous system (CNS) of mice and rats was studied. Intraperitoneal (ip) administration of Ukrain in doses of 9.5 and 19 mg/kg for mice depressed spontaneous motor activity, decreased body temperature and potentiated the action of hexobarbital. Only in a dose of 19 mg/kg Ukrain produced analgesic action in the hot plate test. It had no protective effect against electroshock or pentetrazol-induced seizures. In rats, ip administration of Ukrain in dose of 14 and 28 mg/kg potentiated the action of amphetamine and apomorphine but had no effect on catalepsy induced by haloperidol. Ukrain used in dose 9.5, 14, 19 and 28 mg/kg antagonized the head twitches induced by 5-HTP and hyperthermia-induced by m-CPP. Biochemical studies indicated that Ukrain did not affect the NA and DA concentrations in the whole rats' brain and did not affect the 5-HT and 5-HIAA concentrations in the whole brain of rats. These findings demonstrate that the central action of Ukrain involves the stimulation of the dopaminergic system and the inhibition of the serotoninergic system.

Administration, Oral↗
PubMedDate not supplied

Influence of calcium channel blockers on pentylenetetrazol and electroshock-induced convulsions in mice.

Nifedipine (2.5-10 mg/kg) and verapamil (2.5 and 10 mg/kg) offered some protection against pentylenetetrazol (100 and 130 mg/kg)-induced seizure activity in mice. No protection was provided by diltiazem (1.25-10 mg/kg) in this model of experimental epilepsy. Repeated administration of calcium channel blockers (CCBs) in doses of 5 and 10 mg/kg twice daily for three days resulted in no protective effect against pentylenetetrazol. Regarding electroconvulsions, nifedipine (2.5-10 mg/kg) showed the best anticonvulsive action--for instance, in the dose of 10 mg/kg (60 min--treatment time) it elevated the threshold for electroconvulsions from 7.1 to 10.5 mA. Diltiazem (up to 10 mg/kg) and verapamil (up to 20 mg/kg) were considerably less potent in this respect. After repeated administration, only nifedipine (5-10 mg/kg) retained its protective action against electroconvulsions.

Animals↗
PubMedDate not supplied

Participation of 5-hydroxytryptamine in anticonvulsive action of benzodiazepines.

The influence of several compounds activating or producing hypofunction of the serotonergic system was studied on the convulsive threshold and anticonvulsive action of benzodiazepines (chlordiazepoxide, diazepam, oxazepam, nitrazepam) in the pentylenetetrazol test. No changes in the convulsive threshold either for clonic, nor for tonic phase were found. However, the anticonvulsive action of benzodiazepines was enhanced by 5-hydroxytryptophan, 5-methoxytryptamine (given together with pargyline), or fenfluramine. p-Chlorophenylalanine and methergoline did not affect, but cyproheptadine enhanced the anticonvulsive action of most of benzodiazepines tested.

5-Hydroxytryptophan↗
PubMedDate not supplied

The effect of beta-adrenergic receptor blocking agents on hypertensive action of noradrenaline injected into the lateral ventricle of rat brain.

Noradrenaline (NA), 100 microgram intraventricularly (ivtr), produces an evident hypertension, lasting for up to 15 min. A previous ivtr administration of propranolol (100 and 500 microgram), alprenolol (100 microgram), sotalol (100 microgram), (-)INPEA (100 microgram), (+)INPEA (100 microgram), Ko 1366 (100 and 200 microgram), or practolol (20 microgram) abolishes the hypertensive action of NA. The results indicate that the central nervous system of the rat contains structures similar to the peripheral beta-adrenoceptor, and that they are involved in the central regulation of circulation.

Adrenergic beta-Antagonists↗
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Studies on the participation of the dopaminergic system in the central effects of chelidonine.

Chelidonine administered to rats in doses of 25, 50, 100 and 200 mg/kg ip exerted an inhibitory effect on the dopaminergic structures in the rat. It was shown that chelidonine decreased amphetamine- and apomorphine-induced hyperactivity and inhibited amphetamine and apomorphine sterotype. Besides, chelidonine significantly inhibited the yawning and penile erection produced by apomorphine. However, chelidonine potentiated also catalepsy caused by haloperidol. In doses of 100 and 200 mg/kg ip chelidonine depressed the whole brain dopamine (DA) concentrations and enhanced DA utilization.

Alkaloids↗
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Influence of some psychotropic drugs on the ethanol elimination by the isolated liver of rats chronically fed with ethanol.

During a 4-week period the rats received ethanol (EtOH), as their only drinking fluid, in a concentration ranging from 6% to 20%. In the period of 72 hours after EtOH withdrawal the rats received diazepam (DZP), imipramine (IMI) or caffeine (CAFF) i.p. twice a day in a 12-hours interval. In the experiments carried out on the livers isolated from these rats, we observed the diminution of the rate of EtOH elimination from the perfusate by the livers of DZP and IMI treated rats. CAFF did not change the rate of EtOH elimination.

Administration, Oral↗
PubMedDate not supplied

Effect of chronic ethanol treatment and the abstinence period on the ethanol elimination by isolated rat liver lesioned by carbon tetrachloride.

The study was carried out on perfused livers isolated from rats receiving ethanol (EtOH) as their only drinking fluid for the period of 4 weeks. Twelve, 24, 72 and 120 hours after EtOH withdrawal the livers were isolated and perfused with 100 ml of perfusion mixture with addition of EtOH (0.2% final concentration). After 12 hours of EtOH withdrawal acceleration of the EtOH elimination from perfusate was observed. It returned to the control level after 24 hours, but after 72 and 120 hours of abstinence the rate of EtOH elimination from perfusate was found to diminish. CCl4 injected to the rats in doses of 2 and 5 mmoles/kg once a week for the period of 4 or 8 weeks, resulted in decreased EtOH elimination from the perfusate. In the EtOH-drinking group previously treated with CCl4 we found that irrespective of the time of EtOH withdrawal, EtOH elimination did not differ from that in the respective CCl4 treated group, only 12 hours after its withdrawal EtOH elimination was decreased in livers injured with CCl4 in dose of 5 mmoles/kg.

Administration, Oral↗
PubMedDate not supplied

Central effects of octopamine administered into the lateral ventricle of rats.

Central effects of octopamine administered into the lateral ventricle of rats. Acta physiol. pol., 1979, 30 (4): 445--453. Octopamine (100, 250 and 500 micrograms/rat i.v.c.) exerted a stimulating effect on the central nervous system in rats, which was evidenced by increased spontaneous and basal motor activity, increased exploratory activity in the free-field test, and also increased motor activity in reserpinised rats pretreated with alpha-MT or nialamide. Octopamine decreased the body temperature and prolonged the duration of hexobarbital-induced sleep, and increased amphetamine-induced hyperactivity. Locomotor agitation after octopamine injection was inhibited by phenoxybenzamine and yohimbine in a dose of 10 mg/kg i.p.

Animals↗
PubMedDate not supplied

The central action of drugs affecting beta-adrenergic receptor. IV. The influence of intraventricularly administered drugs affecting beta-adrenergic receptor on blood pressure in rats.

Isoprenaline, propranolol, alprenol and sotalol administered intraventricularly (ivc) to anaesthetized rats induce hypotension. Propanolol and alprenolol given ivc to rats pretreated with isoprenaline increase blood pressure up to the values equal to those, previous to isoprenaline administration; another isoprenaline dose acts slightly hypotensively.

Adrenergic beta-Antagonists↗