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D B Beleslin

Publications and source records attributed to D B Beleslin.

At least 19 recordsLinked to original sources
PubMed2002

Emesis: antiemetic effect of cyclophosphamide at central receptors of multitransmitter system in the cat.

The antiemetic and emetic actions of the anticancer drug cyclophosphamide injected intracerebroventricularly (i.c.v.) and intravenously (i.v.) through chronically implanted cannulae were investigated in unanaesthetized cats. Cyclophosphamide in single doses was injected into the cerebral ventricles and intravenously for 5 consecutive days. The antiemetic effect was regularly obtained, whereas the emetic effect was unpredictable and of low incidence. The antiemetic effect of i.c.v. and i.v. cyclophosphamide was assessed, when the neurotoxic (mydriasis, restlessness, emesis, ataxia, muscular weakness) signs subsided, against i.c.v. noradrenaline- and clonidine-induced emesis. Noradrenaline-induced emesis was dose-dependently and dose-independently inhibited with i.c.v. and i.v. cyclophosphamide. On the other hand, i.c.v. cyclophosphamide inhibited the clonidine-induced emesis in dose-independent manner, while i.v. injection of the anticancer drug had no significant effect on the emesis. The inhibition of emesis was consistently obtained and no significant differences in the antiemetic potency were found between 1 and 5 consecutive days of treatment with cyclophosphamide. However, the inhibition of noradrenaline-induced emesis was dose-dependent only after first administration of i.c.v. cyclophosphamide. It is assumed that noradrenaline acts at alpha-adrenoceptors within the area postrema and clonidine at alpha-adrenoceptors within and outside the area postrema as well as at muscarinic cholinoceptors, 5-hydroxytryptamine, dopamine and histamine H1 and H2 receptors, outside the area postrema, of multitransmitter system subserving the central regulation of emesis. It is suggested, therefore, that the antiemetic effect of cyclophosphamide at the receptors of the multitransmitter central emetic system is non-specific. In general, the antiemetic effect, even non-specific, of an anticancer drug could have practical implication. Namely, when a combination of two or more anticancer drugs are used for chemotherapy, the emesis could not occur if one of them could antagonize the emesis induced by other anticancer drug/s. Finally, cyclophosphamide injected i.c.v., but not i.v., evoked shortlasting emesis in about 20% of cats. Since the emesis was unpredictable and of low incidence it was not possible to study the mechanism/s and site/s of action of the anticancer drug.

Animals↗
PubMed2000

Effects of nicotine, dimethylphenylpiperazinium and tetramethylammonium on smooth muscles from feline and human gastric corpus.

Both excitatory and inhibitory intrinsic neurons could be found within the gastric wall, both of them receiving innervation from vagal fibres and being sensitive to nicotine. The effects of three nicotine receptor agonists, nicotine, tetramethylammonium (TMA) and 1,1-dimethyl-4-phenylpiperazinium (DMPP), on contractile activity of preparations isolated from feline and human gastric corpus wall were investigated. While DMPP (3.5x10(-8) to 5.9x10(-4)m) did not affect either spontaneous contractions or basal tension of isolated preparations from both species, TMA produced concentration-dependent tonic contractions of both circular and longitudinal isolated preparations from human (3.66x10(-5) to 5.10x10(-3)m) and feline (6. 1x10(-7) to 2.1x10(-3)m) stomach. On the other hand, nicotine (4. 1x10(-8) to 7.0x10(-4)m) produced concentration-dependent relaxation of only circular isolated preparations from feline gastric corpus. The effect of nicotine was sensitive to mecamylamine, and not to pancuronium, while the effect of TMA was sensitive to both mecamylamine and pancuronium. Although in our experiments DMPP had no effect, its excitatory action on gastric intrinsic neurons through the hexamethonium-insensitive pathway had already been described. The results of our study suggest that two different types of ganglion nicotine receptor exist together within the wall of feline stomach: (1) type N(N1)which is involved in relaxation and is sensitive only to nicotine and mecamylamine, and not to DMPP, TMA and pancuronium; (2) and type N(N2)which is involved in contraction of gastric muscle and sensitive to DMPP, TMA, mecamylamine and pancuronium, and not to nicotine.

Adult↗
PubMed1997

Clonidine-induced emesis: a multitransmitter pathway concept.

The emetic effect of clonidine injected into the cerebral ventricles through chronically implanted cannulae was investigated in unanaesthetized cats. Clonidine (0.1-300 micrograms) induced dose-dependent and shortlasting emesis. The emesis induced by the supramaximal dose of clonidine (100 micrograms) was not abolished after the ablation of area postrema. Both the alpha 2 adrenoceptor blocking agent idazoxan and the mixed alpha 1 and alpha 2 adrenoceptor antagonist phenoxybenzamine, injected intracerebroventricularly, attenuated or abolished the emesis induced by clonidine (100 micrograms). On the other hand, the alpha 2 adrenoceptor blocking agent yohimbine, the alpha 1 adrenoceptor blocking drug prazosin and the non-selective beta-adrenoceptor antagonist propranolol, injected into the cerebral ventricles, had no significant effect on clonidine-induced emesis. The antimuscarinic drug atropine injected into the cerebral ventricles prevented the clonidine-induced emesis in a dose-dependent manner. The dopamine antagonist chlorpromazine, the 5-hydroxytryptamine blocking agent methysergide and the histamine H1 and H2 receptor antagonists, antazoline and cimetidine, injected intracerebroventricularly reduced or abolished the emesis produced by clonidine. The ganglionic blocking substance mecamylamine and the opioid antagonist naloxone, all injected into the cerebral ventricles, had no significant effect on clonidine-induced emesis. In cats pretreated with the intracerebroventricular competitive inhibitor of the synthesis of catecholamines, alpha-methyl-p-tyrosine, as well as with the inhibitor of acetylcholine synthesis hemicholinium-3, the emesis caused by clonidine was depressed or abolished. The clonidine-induced emesis was also abolished when catecholamine stores were depleted by intracerebroventricular reserpine. However, the clonidine-induced emesis was not significantly changed when 5-hydroxylryptaminergic nerve terminals were damaged by 5,6-dihydroxytryptamine. It follows, therefore, that cholinergic and noradrenergic mechanisms are of basic importance for the emetic action of clonidine. With regard to receptors, the emesis induced by clonidine injected into the cerebral ventricles, is mediated at least in part through alpha-adrenoceptors, muscarinic cholinoceptors, 5-hydroxytryptamine receptors and H1 and H2 histamine receptors. These receptors appear to be located mostly presynaptically and they transmit emetic impulses to neurones integrating them into emesis. However, the direct effect of clonidine on postsynaptic receptors cannot be excluded, particularly when muscarinic and 5-hydroxytryptamine receptors are implicated. Taken together, these results point to the existence of a multitransmitter pathway/s outside the area postrema, subserving the central regulation of emesis.

Adrenergic alpha-Agonists↗
PubMed1996

[Tamoxifen: modern drug therapy of estrogen-dependent breast tumors].

Tamoxifen is an antiestrogen drug which is used for adjuvant therapy of patients with estrogen positive receptors in breast cancer. It is a competitive antagonist of estrogen receptors for endogenous and exogenous estradiol, but its anticancer effects cannot be explained only by its action on estrogen receptors. Its main effects are anticancer and endocrine, but it also effects on antithrombin III, HDL cholesterol and biosynthesis of prostaglandins. Low incidence of side effects is its main advantage, but not having causal effects its disadvantage.

Antineoplastic Agents, Hormonal↗
PubMed1995

The role of alpha-adrenergic mechanisms within the area postrema in dopamine-induced emesis.

Intracerebroventricular injection of dopamine (0.5-4.0 mg) produced dose-dependent and short-lasting emesis (1-8 min) in cats, which was abolished after ablation of the area postrema. Relatively selective alpha 2-adrenoceptor antagonists (yohimbine and idazoxan) and a mixed alpha 1- and alpha 2-adrenoceptor antagonist (tolazoline), but not a non-selective alpha 1-adrenoceptor antagonist (prazosin), injected intracerebroventricularly inhibited the emesis induced by intracerebroventricular dopamine. However, dopamine receptor antagonists (chlorpromazine, droperidol, spiperone, domperidone, triflupromazine, sulpiride and metoclopramide), an antimuscarinic drug (atropine), a ganglionic blocking agent (mecamylamine), an opioid receptor antagonist (naloxone) and a 5-HT receptor antagonist (methysergide), all injected intracerebroventricularly, had no significant effect on emesis evoked by intracerebroventricular dopamine. The emetic response to intracerebroventricular dopamine was attenuated in cats pretreated with intracerebroventricular reserpine, 6-hydroxydopamine, alpha-methyl-p-tyrosine and hemicholinium-3. It is postulated that dopamine-induced emesis is mediated through the release of noradrenaline acting at alpha 2-adrenoceptors and that it depends on the integrity of monoaminergic and possibly cholinergic structures within the area postrema. It appears, therefore, that the emetic effect of intracerebroventricular dopamine is mediated by adrenergic rather than dopaminergic mechanisms in the area postrema, at least in the cat.

Adrenergic alpha-Antagonists↗
PubMed1989

Ablation of the area postrema and emesis.

The emetic action of dopamine, norepinephrine, epinephrine, nicotine, dimethylphenyl-piperazinium (DMPP), and 4-m-chlorophenylcarbamoyloxy-2-butynyltrimethylammonium (McN-A-343) injected intracerebroventricularly (i.c.v.) to the unanesthetized cat was investigated and compared. ED50 values (mg) were as follows: nicotine, 0.011; epinephrine, 0.047; norepinephrine, 0.57; DMPP, 0.9; dopamine, 1.66; and McN-A-343, 4.42. The most potent was nicotine, whereas the least active McN-A-343. On the other hand, DMPP produced the longest emetic response, about 30 min, while McN-A-343-induced emesis lasted up to 1 min. The ablation of the area postrema abolished the emetic response to i.c.v. dopamine, norepinephrine, epinephrine, nicotine, and DMPP. However, the emetic response to i.c.v. McN-A-343 was significantly reduced in cats with an ablated area postrema. Taken together, the results obtained show that the area postrema is almost always involved in the central regulation of emesis and that the area postrema represents, in most cats, a common site of confluence of different inputs subserving the emesis.

Animals↗
PubMed1989

The area postrema and the hypertensive effect of angiotensin.

The intracerebroventricular administration of angiotensin II in pentobarbital-anesthetized cats produced dose-dependent increases in the arterial blood pressure without significant changes in the heart rate. The ablation of the area postrema significantly reduced, but did not abolish, the pressor effect of angiotensin injected into the cerebral ventricles. It follows, then, that the central pressor effect of angiotensin is dependent on the integrity of the area postrema and that this central site, at least in part, contributes to the pressor action of endogenous angiotensin.

Angiotensin II↗
PubMed1989

Area postrema: cholinergic and noradrenergic regulation of emesis. A new concept.

In unanaesthetized cats the biochemical mechanisms and the functional characteristics of the emetic action of injection of noradrenaline and McN-A-343, a ganglionic muscarinic stimulant into the cerebral ventricle (i.c.v.) through chronically implanted cannulae were investigated. Both produced dose-dependent and shortlasting emetic response. The emesis evoked by noradrenaline was abolished, whereas the emesis induced by McN-A-343 was not completely blocked after ablation of the area postrema. Further, the emetic response to noradrenaline as well as to McN-A-343 was attenuated or blocked in cats pretreated with 6-hydroxydopamine (i.c.v.) and hemicholinium (i.c.v.); it was abolished in cats pretreated with reserpine (i.c.v.). On the other hand, the emetic response to i.c.v. noradrenaline and to i.c.v. McN-A-343 was not virtually altered in cats pretreated with bretylium (i.c.v.), alpha-methyl-p-tyrosine (i.c.v.) and 5,6-dihydroxytryptamine (i.c.v.). It is postulated that noradrenergic neurones as well as cholinergic axon terminals within the area postrema are necessary for the emetic action of noradrenaline, whereas cholinergic axon terminals within the area postrema subserve the emetic response to McN-A-343. A functional link between cholinergic terminals and noradrenergic neurones as well as a modulatory role of noradrenergic afferents on cholinergic afferents mediating emesis within the area postrema is further proposed. Thus, noradrenergic neurones might represent a common site of confluence of different inputs subserving the emesis in the area postrema. Finally, cholinergic terminals sometimes bypass this area and synapse in the emetic regions of the brainstem regulating emesis.

(4-(m-Chlorophenylcarbamoyloxy)-2-butynyl)trimethy↗
PubMed1988

Emesis induced by 4-(m-chlorophenylcarbamoyloxy)-2-butynyltrimethylammonium chloride (McN-A-343): evidence for a predominant central muscarinic M1 mediation.

The emetic action of 4-(m-chlorophenylcarbamoyloxy)-2- butynyltrimethylammonium chloride (McN-A-343) was investigated in the unanaesthetized cat, after it was injected into the cerebral ventricles, through chronically-implanted cannulae. Intracerebroventricular injection of McN-A-343 produced dose-dependent and shortlasting emesis, which was not completely abolished after ablation of the area postrema. The predominantly selective muscarinic M1 antagonist, pirenzepine as well as the mixed muscarinic M1 and M2 antagonist, atropine, injected into the cerebral ventricles, attenuated or abolished the emesis evoked by intracerebroventricular McN-A-343. Both atropine and pirenzepine produced dose-dependent inhibition of the emesis evoked by McN-A-343. However, the ID50 value for atropine was approximately five times greater than that for pirenzepine. Abolition of McN-A-343-induced emesis only occurred with the largest dose of atropine (1 mg). On the other hand, selected ganglionic blocking agents, an alpha- and beta-adrenoceptor blocking agent, a dopamine antagonist, a 5-hydroxytryptamine antagonist and an antihistamine, all injected into the cerebral ventricles, had no significant effect on emesis evoked by McN-A-343, similarly injected. The emetic response to intracerebroventricular injection of McN-A-343 was attenuated or abolished in cats pretreated with hemicholinium-3, triethylcholine, reserpine and 6-hydroxydopamine, intracerebroventricularly. On the contrary, the emetic response to intracerebroventricular injection of McN-A-343 was not altered in cats pretreated with intracerebroventricular injections of bretylium, alpha-methyl-p-tyrosine and 5,6-dihydroxytryptamine. It is postulated that the emesis produced by McN-A-343, injected into the cerebral ventricles, is mediated through muscarinic M1 receptors.(ABSTRACT TRUNCATED AT 250 WORDS)

(4-(m-Chlorophenylcarbamoyloxy)-2-butynyl)trimethy↗
PubMed1988

[Effect of guanabenz on the peristaltic reflex and on the spontaneous rhythmic movements of the ileum isolated from the rabbit: do the alpha-2-adrenoreceptors constitute a homogenous population?].

The inhibitory effect of the predominantly alpha-2 adrenoceptor agonist, guanabenz, on the peristaltic reflex and on the pendular movements of the rabbit isolated ileum was investigated. Guanabenz depressed or abolished the peristaltic reflex as well as the pendular movements. These effects were concentration-dependent. Guanabenz is much more potent inhibiting the peristaltic reflex (IC50 1 X 10(-7) M) than the pendular movements (IC50 1 X 10(-5) M). The choline ester, acetylcholine restored the peristaltic reflex and the anticholinesterase, eserine, restored the pendular movements previously abolished by guanabenz. During the blockade of the peristaltic reflex produced by guanabenz, the pendular movements were virtually not changed. It is therefore reasonable to suppose that the inhibitory effect of guanabenz reflects the different properties of alpha-2 adrenoceptors associated with cholinergic nerve terminals within the myenteric plexus and the longitudinal smooth muscle subserving the peristaltic reflex and the pendular movements.

Animals↗
PubMed1987

Noradrenaline-induced emesis. Alpha-2 adrenoceptor mediation in the area postrema.

The emetic action of noradrenaline was investigated in unanesthetized cats, after it was injected into the cerebral ventricles through chronically implanted cannulae. Intracerebroventricular injection of noradrenaline produced dose-dependent and shortlasting emesis, which was abolished after ablation of the area postrema. However, copper sulphate, given orally, evoked emesis in cats with an ablated area postrema. The selective alpha-2 adrenoceptor antagonist, yohimbine, as well as the mixed alpha-1 and alpha-2 adrenoceptor blocking drugs, phentolamine, tolazoline, phenoxybenzamine and dihydroergotamine, but not the selective alpha-1 adrenoceptor antagonist, prazosin, all injected into the cerebral ventricles, attenuated or blocked the emesis evoked by intracerebroventricular injection of noradrenaline. Of the alpha-adrenoceptor antagonist, only yohimbine produced dose-dependent inhibition of the emesis induced by noradrenaline. On the contrary, selected beta-adrenoceptor blocking agents, an antimuscarinic drug, a ganglionic blocking agent, an antihistamine, dopamine antagonists and a 5-hydroxytryptamine antagonist, all injected into the cerebral ventricles, had no significant effect on the emesis induced by noradrenaline, similarly injected. The emetic response to intracerebroventricular injection of noradrenaline, as well as to intragastric administration of copper sulphate was not altered in cats pretreated with intracerebroventricular injections of alpha-methyl-p-tyrosine and bretylium. On the other hand, the emetic response to intracerebroventricular injection of noradrenaline and to intragastric administration of copper sulphate was attentuated or blocked in cats pretreated with reserpine intracerebroventricularly. Moreover, in cats pretreated with intracerebroventricular injection of 6-hydroxydopamine and hemicholinium, the emesis induced by intracerebroventricular administration of noradrenaline but not that produced by intragastric injection of copper sulphate, was depressed.(ABSTRACT TRUNCATED AT 250 WORDS)

5,6-Dihydroxytryptamine↗
PubMed1987

Further studies on nicotine-induced emesis: nicotinic mediation in area postrema.

In unanesthetized cats the emetic action of an injection of nicotine into the cerebral ventricle through chronically implanted cannulae was investigated. Nicotine injected in doses of 0.02-1.0 mg produced dose-dependent vomiting, which was abolished after ablation of the area postrema. However, copper sulfate given intragastrically evoked vomiting in cats with an ablated area postrema. The emetic response to intracerebroventricular (ICV) nicotine as well as the vomiting produced by intragastric copper sulfate was depressed or abolished in cats pretreated with ICV reserpine. On the other hand, the emetic response to ICV nicotine and to intragastric copper sulfate was virtually unchanged in cats pretreated with ICV 6-hydroxydopamine and 5,6-dihydroxytryptamine. The duration of vomiting produced by intragastric copper sulfate, but not that of ICV nicotine, was potentiated in cats pretreated with hemicholinium-3. Ganglionic blocking agents, mecamylamine and hexamethonium, injected ICV prevented the vomiting elicited by ICV nicotine. On the other hand, selected anti-muscarinic drugs, alpha and beta adrenergic receptor antagonists, dopamine antagonists, antihistamines and a 5-hydroxytryptamine antagonist all injected into the cerebral ventricle had virtually no effect on the vomiting induced by ICV nicotine. It is postulated that nicotine evokes vomiting by its action on nicotinic receptors within the area postrema but not on catecholaminergic or serotonergic neurones. Finally, acetylcholine could also be involved in the inhibition of the complex mechanisms underlying the central regulation of vomiting.

Acetylcholine↗
PubMed1987

Hypothermia: role of alpha 1- and alpha 2-noradrenergic receptors in the hypothalamus of the cat.

The purpose of this study was to characterize the alpha 1- and alpha 2-noradrenergic receptor sub-types which could mediate the hypothermic response produced by norepinephrine (NE) and other alpha-noradrenergic agonists applied to the thermosensitive zone of the hypothalamus. An array of four guide tubes was implanted stereotaxically so that their tips rested just above the anterior hypothalamic, preoptic area (AH/POA) of the cat. Following post-operative recovery, a micro-injection of an agonist or antagonist of NE receptors or control CSF vehicle was given in a volume of 1.0-2.0 microliter in the AH/POA in each of the unrestrained cats. The alpha 1-noradrenergic receptor agonist, phenylephrine, but not methoxamine, applied to the AH/POA produced a dose-dependent hypothermia of up to 2.0 degrees C. When applied similarly, the alpha 2-noradrenergic agonist clonidine, as well as norepinephrine, which acts on both alpha 1- and alpha 2-noradrenergic receptors, also induced a decline in the cat's core temperature of up to 1.5 degrees C. The hypothermic response of clonidine was inhibited by pre-treatment of the AH/POA with a micro-injection of the selective alpha 2-noradrenergic blocking agent, yohimbine. However, yohimbine given similarly in the cat's AH/POA potentiated significantly both the phenylephrine and norepinephrine-induced hypothermia. The combined alpha 1-, alpha 2-noradrenergic receptor antagonist, phentolamine, also injected into AH/POA inhibited the thermolytic response evoked by both phenylephrine and norepinephrine, whereas it was virtually ineffective against the clonidine-induced hypothermia. These results, therefore, strongly suggest that both alpha 1- and alpha 2-noradrenergic receptors subserve the coordinated thermoregulatory mechanisms in AH/POA which are required for the functional dissipation of body heat and the consequent evocation of hypothermia.

Animals↗
PubMed1987

Studies of thyrotropin-releasing hormone (TRH)-induced defecation in cats.

In unanesthetized cats, defecation produced by thyrotropin-releasing hormone (TRH) was investigated after its injection into the cerebral ventricle (ICV) through chronically implanted cannulae. TRH injected in doses from 0.1 to 1.0 mg into the cerebral ventricle evoked defecation which was not dose-dependent. The antimuscarinic drug, atropine, the ganglionic blocker, mecamylamine, the alpha and beta adrenergic blocking agents, yohimbine and propranolol, the dopamine antagonist, chlorpromazine, the 5-hydroxytryptamine antagonist, methysergide, and the antihistamine, antazoline, all injected into the cerebral ventricle had virtually no effect on the defecation evoked by TRH injected similarly. In cats pretreated with ICV reserpine, 5,6-dihydroxytryptamine and hemicholinium-3, the defecation induced by ICV TRH was not significantly changed. On the other hand, in cats pretreated with ICV 6-hydroxydopamine, the defecation caused by ICV TRH was potentiated. Therefore, it is concluded that TRH-induced defecation could not be related to central catecholaminergic, 5-hydroxytryptaminergic and cholinergic receptors, but rather to central TRH sites in the cat.

Animals↗