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Biomedical subjects

Z Kleinrok

Publications and source records attributed to Z Kleinrok.

At least 379 records · Page 21Linked to original sources
PubMedDate not supplied

Effects of histamine and H1 and H2-receptor antagonists on the wet-dog-shaking episodes in rats induced with lithium chloride.

In the experiments carried out on Wistar rats it was demonstrated that histamine administered intraventricularly had no effect on the number of wet-dog-shaking episodes induced with lithium chloride. Thenalidine and antazoline, antagonists of the H1 receptor, and cimetidine and ranitidine, antagonists of the H2 receptor reduced the number of shaking episodes proportionally to the dose. These results may suggest that the reduction of the number of shaking episodes induced with lithium chloride was connected with blockade of histamine receptors, although an indirect effect of H1 and H2-receptor antagonists on the serotoninergic and cholinergic systems cannot be ruled out.

Animals↗
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The locomotor and exploratory activities in rats after lesion of hippocampal pyramidal cells with kainic acid.

The effect of single kainic acid (KA) intracerebroventricular(icv) injection on spontaneous locomotor, exploratory, basal and total activities in rats measured a different times was tested. Whereas at 3 hr after KA icv administration an increase of the total, basal and spontaneous activities of rats were observed, a great decrease of the exploratory activity was noted. KA at 24 hr after its administration depressed all types of rats activities. From 72nd hr after KA icv injection a significant increase in the total, exploratory and spontaneous locomotor activities without changes in the basal activity was observed. The above mentioned changes persisted up to 10-20 days after KA administration. The histological examinations showed evident neuropathologic changes in hippocampal stratum pyramidale. The most evident changes concerned the hippocampal areas CA3/CA4 and CA1. There were observed shrinking, narrowing and fragmentation of pyramidal cells. An intense progressive gliotic reaction was present among the fragmented cells, the layer of pyramidal cells being considerably diminished.

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Preliminary studies on the central action of new 1,5-benzodiazepine derivatives.

Preliminary studies were carried out on pharmacological central action of 13 newly synthesized 1,5-benzodiazepine derivatives (compounds W1--W13), in comparison with allobarbital and diazepam. The results of the tests indicated that two of the compounds seem to be particularly interesting owing to their ataractic properties, low toxicity and none or weak hypnotic action and negligible ability to disturb the motor coordination.

Animals↗
PubMedDate not supplied

Effect of histamine and H1 and H2 receptors antagonists on carbachol-induced wet-dog shakes in rats.

Intracerebroventricular administration of carbachol chloride induced a characteristic wet-dog shake response in rats. Histamine did not change the number of wet-dog shakes during a 60 min observation but intensified the number of episodes in the first 30 min of the experiment. Antagonists of H1 (thenalidine and antazoline) and H2 (cimetidine and ranitidine) receptors, attenuated carbachol-induced wet-dog shakes. It may be suggested that inhibition of the central histaminergic structures decreased central cholinergic activity.

Animals↗
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Effects of histamine and H1 and H2-receptor antagonists on wet-dog-shake episodes in rats induced with tranylcypromine and 5-methoxytryptamine.

Intraperitoneally administered tranylcypromine and 5-methoxytryptamine induced in rats the so called wet-dogs-shake behaviour. Histamine injected intraventricularly had no effect on the number or episodes of this behaviour during the first 40 minutes of observation. On the other hand, dimaprit in doses of 5 micrograms/rat injected also intraventricularly increased the number of these episodes. Thenalidine and antazoline--antagonists of the H1-receptor, and cimetidine and ranitidine--antagonists of the H2-receptor, decreased the number of these episodes proportionally to the injected dose. Similar effects were obtained after cimetidine injection into the lateral ventricle. In the light of these observations it may be supposed that these antihistaminic agents exert an inhibitory effect not only on the histaminergic system but decrease indirectly also the activity of the serotoninergic system.

5-Methoxytryptamine↗
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Effect of combined GABA-ergic and dopaminergic stimulation on the action of some antiepileptic drugs in pentetrazol-induced convulsions.

Apomorphine (up to 10 mg/kg) and amantadine (up to 100 mg/kg) did not affect pentetrazol-induced convulsions in mice. One of two GABA-ergic agonists tested, baclofen (10 mg/kg), decreased seizure susceptibility (except for the clonic phase) while another, amino-oxyacetic acid (up to 20 mg/kg) had no effect. Combined treatment was most effective in the case of baclofen (5 mg/kg) and amantadine (100 mg/kg) where number of animals with tonic seizures was decreased. Dopaminergic stimulation did not modify the action of some anticonvulsants tested. However, GABA-ergic stimulation resulted in a marked potentiation of the action of carbamazepine (10 mg/kg) and acetazolamide (20 mg/kg), being less pronounced in reference to diazepam (0 . 5 mg/kg) in lefadol (20 mg/kg). On the other hand, combined treatment with GABA-ergic and dopaminergic stimulants was shown to enhance the action of carbamazepine and acetazolamide, but not in the clonic phase. The obtained results suggest effectiveness of GABA-ergic stimulation in the case of all drugs tested and the combined treatment with GABA-ergic and dopaminergic agonists in potentiating the effects of some antiepileptics.

Animals↗
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The influence of insulin hypoglycemia on central dopaminergic structures of the rat.

Daily administration of insulin, 2 U/kg/day for 9 days, leads to a marked increase in the activity of central dopaminergic structures, reflected by an increase in the apomorphine or amphetamine-induced stereotypy and a decrease in fluphenazine-induced catalepsy. These changes are accompanied by a depression of cerebral dopamine and noradrenaline levels and a depression of noradrenaline utilization in the brain.

Amphetamine↗
PubMedDate not supplied

Prevention of kainic acid-induced seizure-like activity by antiepileptic drugs.

Intracerebroventricular kainic acid (KA) injections produced a seizure-like activity syndrome in mice. It was shown that some antiepileptic drugs (lefadol, depakine, phenobarbital) inhibited this syndrome, diazepam being the most effective in this respect. However, acetazolamide and diphenylhydantoin exerted a rather weak or negligible effect even when given in high doses. Present results may suggest that the effects of intracerebroventicular injections of KA may be employed to test antiepileptic properties of drugs.

Acetazolamide↗
PubMedDate not supplied

Effects of drugs stimulating and blocking M and N cholinergic receptors on GABA level and GAD activity in rat striatum.

In the experiments on Wistar rats it was demonstrated that pilocarpine and physostigmine decreased the GABA level in the striatum. This change was prevented by atropine. Lobeline and nicotine exerted a biphasic effect on GABA level: given in small doses 15 min before decapitation they raised, and in higher doses they decreased this level. This was due to their biphasic effect on the cholinergic receptor N. The changes in GABA level produced by stimulation of N receptors by lobeline and nicotine were prevented by mecamylamine and d-tubocurarine, and in part also by atropine and propranolol. This suggests an indirect participation of M and beta receptors in the transmission of impulses from the cholinergic receptors N to the GABA-ergic system. The effect of the tested substances on GAD activity was not uniform. No strict correlation was demonstrated between GAD activity and GABA level.

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The locomotor and stereotype response to dopaminergic drugs and caffeine after intracerebroventricular kainic acid in rats.

The effects of single kainic acid (KA) (0.1 microgram) intracerebroventricular injection on locomotor and stereotypy responses to amphetamine and apomorphine, and on locomotor response to caffeine were measured at different intervals (24, 120, 240, 480 h). The responses to amphetamine and caffeine were markedly elevated during the all period. In contrast, the responses to apomorphine remained unchanged. Histological examination showed severe destructions of neurons and fibres within the nucleus caudatus and the permanent loss of hippocampal pyramidal cells.

Amphetamine↗
PubMedDate not supplied

Shuttle behavior in rats after lesion of hippocampal pyramidal cells with kainic acid.

Rats with bilateral lesions of hippocampal pyramidal cells in the subfield CA 3 with intracerebroventricular kainic acid (0.1 microgram/2 microliter) made more shuttle responses to a buzzer in Pavlovian paradigm, classical conditioning and two-way active avoidance but did not differ remarkably in pseudoconditioning and avoidance conditioning without stimulus pairing, than sham-operated and intact control rats. Animals with unilateral lesion in the CA 3 hippocampal subfield showed no differences in these shuttle situations. The results suggest that CA 3 hippocampal pyramidal cells are of particular importance to the establishment of the stimulus-stimulus relations in the brain.

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Central neurotropic activity of homovanillic acid.

In experiments performed on male Wistar rats in was shown that i.v.c. administered homovanillic acid (HVA) in a dose of 50 micrograms exerted an inhibitory effect on the locomotor activity. In this dose HVA potentiated also the cataleptogenic effect of haloperidol and amphetamine-induced locomotor hyperactivity. On the other hand, the higher dose HVA (200 micrograms) increased locomotor activity, potentiated amphetamine-induced locomotor hyperactivity, but antagonized apomorphine-induced stereotypy. HVA in a dose of 50 micrograms enhanced the turnover of dopamine, and in a dose of 200 micrograms the turnover of noradrenaline in rat brain. The obtained results indicate that the effects of HVA on animal behaviour are connected with its action on catecholaminergic systems in the brain, especially on the dopaminergic receptors. The inhibitory effect of small dose of HVA appears to be presynaptic and the stimulatory effect of a high dose of HVA seems to be postsynaptic. Moreover, the experiments with a high dose of HVA suggest that it may act in the central nervous system either by altering the distribution of endogenous monoamines or by mimicking the action of monoamines on specific synaptic receptors.

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PubMedDate not supplied

Brain dopamine and seizure susceptibility in mice.

In electroshock test apomorphine appeared without effect, D, L-amphetamine and L-DOPA (in a high dose) elevated the convulsive threshold, while amantadine decreased it. Among investigated dopamine (DA) receptor blockers spiperone, pimozide and fluphenazine lowered the threshold, haloperidol being without effect. The convulsive threshold elevated by L-DOPA was not affected by neuroleptics and phentolamine but on the other hand DA receptor blockers and phentolamine anatagonized the effect of D, L-amphetamine. The effect of amantadine was not influenced by neuroleptics. In pentylenetetrazol (PTZ) test only amantadine and L-DOPA (in high doses) affected the threshold, increasing seizure susceptibility; the above effect was not abolished by pimozide. Our results seem to indicate that the activity of brain DA system seems not to be involved directly in the susceptibility to electrogenic or PTZ-induced seizures in mice.

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The influence of GABA-ergic system on clonidine analgesia in rats.

The effect of agonists and antagonists of GABA-ergic system on analgesia induced by clonidine was investigated in the rat. The compounds activating (muscimol, 1 mg/kg and aminooxyacetic acid; AOAA, 25 mg/kg) or inhibiting GABA-ergic receptors (bicuculline and picrotoxin, in subconvulsive doses 0.5-1 mg/kg) do not change clonidine-induced analgesia. Only the higher dose (2 mg/kg) of muscimol, bicuculline or picrotoxin affected clonidine-induced analgesia. Baclofen, contrary to other GABA agonists, markedly potentiated clonidine-induced analgesia in the dose dependent manner. These results suggest that compounds activating and inhibiting GABA A receptors (muscimol, AOAA, bicuculline and picrotoxin) have a weak influence on clonidine induced analgesia as compared to the effect of baclofen (agonist of GABA B receptors).

Aminooxyacetic Acid↗
PubMedDate not supplied

Synthesis and biological evaluation of derivatives of N-[4-substituted-1-piperazinylalkyl]-1-(butyl,aryl)-2,5- dimethylpyrrole-3,4-dicarboxymide (Part II).

A series of new N-[4-substituted-1-piperazinyl-alkyl]-3,4-pyrroledicarboxyimides 7 have been prepared by reaction of N-haloalkylimide derivatives 6 with corresponding N-monosubstituted piperazines. Compounds 7 tested in preliminary pharmacological investigation produced a general depressive action on the central nervous system.

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