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Query: UMLS:C0020672 (hypothermia)
 17,327 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Systemic administration of apomorphine induces hypothermia in anaesthetized rats as well as in conscious rats exposed to an ambient temperature of 22 degrees C. The central nature of this effect is confirmed by the antagonism exerted by haloperidol and the lack of antagonism with domperidone. Dopamine receptors involved in the hypothermic effect of apomorphine seem to be located in the preopticus medialis nucleus (p.o.m.n.) of the hypothalamus since: (i) injections of apomorphine (5 ng), dopamine (100 ng) or (+)-amphetamine (50 ng) into this nucleus induce hpothermia, (ii) haloperidol injected into the p.o.m.n. antagonizes the hypothermic effect of a systemic administration of apomorphine, (iii) heat lesions of the p.o.m.n. strongly reduce the hypothermic effect of a systemic injection of apomorphine.
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PMID:Evidence for thermoregulatory dopaminergic receptors located in the preopticus medialis nucleus of the rat hypothalamus. 610 63

Noradrenaline (NA), adrenaline (ADR), isoprenaline (ISO) and dopamine (DA) were given through a chronically implanted cannula in the lateral cerebral ventricle of Mastomys natalensis. Low doses of NA (0.05-0.25 microgram) reduced rectal temperature while larger doses (0.35 microgram upwards) produced dose-dependent hyperthermia. The hypothermic effect was antagonised by alpha-adrenoceptor and the hyperthermia by beta-adrenoceptor antagonists. alpha-Methyl noradrenaline produced less hyperthermia but it antagonised the hyperthermic effect of NA. Adrenaline (0.1-10 microgram) was ineffective per se but when given after tolazoline it produced hyperthermia and after propranolol it produced hypothermia. The dose-dependent hyperthermia with isoprenaline (0.1-10 microgram) was blocked by propranolol and MJ-1999. Dopamine (0.5-20 microgram) and its agonists apomorphine, amantadine and BS 9641 produced hyperthermia which was antagonised by haloperidol and pimozide but not by alpha- or beta adrenoceptor antagonists. Noradrenaline (1.0 microgram) produced hypothermia at ambient temperature of 10 degrees C and 16 degrees C. It had no effect at 20 degrees C which seems to be the thermoneutral zone for mastomys. The hyperthermic effect at 33 degrees C was less than at 24 degrees C. Dopamine (10 micrograms) response was attenuated at 33 degrees C and unaffected at other ambient temperatures. It is concluded that alpha- and beta-adrenoceptors and DA-receptors exist in the central thermoregulatory mechanism in mastomys. The alpha-receptors are concerned with lowering the body temperature whereas the beta-receptors and DA-receptors are involved in raising it.
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PMID:The effect of intracerebroventricular administration of catecholamines and their antagonists on rectal temperature of Mastomys natalensis. 612 Apr 69

These studies were designed to determine the dose-response autonomic and behavioral thermoregulatory effects and the motor effects of dopamine (DA) and prostaglandin E1 (PGE1) injected into the lateral cerebral ventricles of rats. These studies were made possible with a computer-controlled thermocline that permits freely moving rats to select preferred ambient temperatures ranging between 7 and 39 degrees C. All rats were studied with the thermocline gradient both on and off to control for nonspecific effects. PGE1 (0, 0.1, 0.2, 0.5, 1.0 micrograms) produced a dose-related increase in core temperature and produced a dose-related selection of warmer ambient temperatures. Dopamine (0, 50, 100, 200, 400 micrograms) produced a dose-related hypothermia and cold-seeking behavior. Without the gradient, DA-injected rats did not become as hypothermic as in the gradient-on condition. When the gradient was available, rats showed a significant rebound increase in core temperature 50-80 min after DA which did not occur when the gradient was off. Overall, DA induced increases in motor activity, but, during the first 10 min after injection while the gradient was on, the rats made stable selections of cool ambient temperatures and showed reduced activity. Conversely, the behavioral effect of PGE1 did not facilitate the autonomically mediated heat gain. These results emphasize the necessity of creating behavioral options for animals in order to fully evaluate drug effects on thermoregulation.
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PMID:Behavioral thermoregulation, core temperature, and motor activity: simultaneous quantitative assessment in rats after dopamine and prostaglandin E1. 654

A 69 year-old male with ischemic heart disease indicated for coronary artery bypass grafting was scheduled for carotid microendoarterectomy. We induced mild hypothermia technique with vasodilation and surface cooling by convecting warming device. We examined hemodynamics by pulmonary artery catheter. Anesthesia was induced with thiamylal, fentanyl, midazolam and isoflurane in nitrous oxide and oxygen. Following administration of vecuronium, trachea was intubated. Pulmonary artery catheter was inserted from the femoral vein. Dopamine, dobutamine 3-5 micrograms.kg-1.min-1 and PGE1 5-10 ng.kg-1.min-1 were continuously administered to keep peripheral blood circulation and cardiac output (CO). Systemic vascular resistance decreased from 1800 to 591 dyne.s.cm-5 and CO increased from 2.8 to 6.9 l.min-1. The occlusion of blood flow of the right carotid artery for 40 min at 34.5 degrees C of rectal temperature did not cause any neurological deficits. No other complications such as arrhythmia, myocardial ischemia and bleeding tendency were observed. Keeping peripheral blood circulation and uniform cooling and warming are important in inducing mild hypothermia safely in a patient with ischemic heart disease.
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PMID:[Mild hypothermia anesthesia for carotid microendoarterectomy in a patient with ischemic heart disease]. 951 37

These studies were conducted to examine the differential response to a drug challenge under varied experimental test conditions routinely employed to study drug-induced behavioral and neurophysiological responses in rodents. Apomorphine, a nonselective dopamine agonist, was selected due to its biphasic behavioral effects, its ability to induce hypothermia, and to produce distinct changes to dopamine turnover in the rodent brain. From such experiments there is evidence that characterization and detection of apomorphine-induced activity in rodents critically depends upon the test conditions employed. In rats, detection of apomorphine-induced hyperactivity was facilitated by a period of acclimatization to the test conditions. Moreover, test conditions can impact upon other physiological responses to apomorphine such as drug-induced hypothermia. In mice, apomorphine produced qualitatively different responses under novel conditions when compared to those behaviors elicited in the home test cage. Drug-induced gross activity counts were increased in the novel exploratory box only, while measures of stereotypic behavior were similar in both. By contrast, apomorphine-induced locomotion was more prominent in the novel exploratory box. Dopamine turnover ratios (DOPAC:DA and HVA:DA) were found to be lower in those animals exposed to the exploratory box when compared to their home cage counterparts. However, apomorphine-induced reductions in striatal dopamine turnover were detected in both novel and home cage environments. The implications of these findings are discussed with particular emphasis upon conducting psychopharmacological challenge tests in rodents.
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PMID:Test conditions influence the response to a drug challenge in rodents. 1068 78

Dopamine agonist-induced hypothermia has been proposed to be mediated by the D3 receptor (D3R), as it is elicited by (+)7-OH-DPAT and antagonized by S 14297, two putative D3R-preferential ligands. Here we show, however, that S 14297 is a full and partial agonist at D3R and D2R, respectively. Hypothermia was induced in rats by agonists with potencies correlated with their D3R and D2R functional potencies, and was reversed by antagonists, with a rank order of potency typical of the D2R. Moreover, BP 897, a highly potent and selective but partial D3R agonist was inactive in producing hypothermia or reversing (+)7-OH-DPAT-induced hypothermia. (+)7-OH-DPAT was as potent and efficient in inducing hypothermia in wild-type as in D3R-deficient mice. Hence, our results suggest that hypothermia does not result from a selective stimulation of the D3R.
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PMID:Role of dopamine D3 receptors in thermoregulation: a reappraisal. 1068 62

TC-2559 [(E)-N-Methyl-4-[3-(5-ethoxypyridin)yl]-3-buten-1-amine] is a novel nicotinic agonist markedly more selective than recently reported novel nicotinic receptor ligands (selectivity ratio for central nervous system (CNS) to peripheral nervous system (PNS)>4000). TC-2559 competes effectively with [3H]-nicotine binding (K(i)=5 nM) but not with [125I]-bungarotoxin (>50,000 nM). Dopamine release from striatal synaptosomes and ion flux from thalamic synaptosomes indicate that TC-2559 is potent and efficacious in the activation of CNS receptors and significantly reduced glutamate-induced neurotoxicity in vitro. TC-2559 has no detectable effects on muscle and ganglion-type nicotinic acetylcholine receptors at concentrations up to 1 mM. TC-2559 significantly attenuates scopolamine-induced cognitive deficits in a step-through passive avoidance task. Acute and repeated oral dosing of TC-2559 enhances performance in a radial arm maze task. In contrast to the effects of equimolar concentrations of (-) nicotine, TC-2559 does not induce hypothermia and locomotor activity is not enhanced following repeated daily administration of 14 days. TC-2559 has a markedly enhanced CNS-PNS selectivity ratio and an intra-CNS selectivity as evidenced by the improved cognition without increased locomotor activity. The in vitro and in vivo studies in the present study suggest that TC-2559 has the desired profile to be further evaluated as a potential therapeutic agent for neurodegenerative diseases.
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PMID:TC-2559: a novel orally active ligand selective at neuronal acetylcholine receptors. 1109 99

A single high dose of apomorphine (10 mg x kg(-1)) produced not only contextual sensitization to and conditioning of climbing behavior, but also context-independent tolerance to hypothermia. MK-801 (0.15 and 0.3 mg x kg(-1)) inhibited contextual sensitization to and conditioning of climbing behavior. Development of tolerance to hypothermia was also inhibited by MK-801. Dopamine D1 antagonist, SCH23390 (0.5 mg x kg(-1)), but not D2 antagonist, sulpiride, inhibited sensitization to and conditioning of climbing behavior. D2 antagonist, sulpiride (50 mg x kg(-1)), but not D1 antagonist, SCH23390, inhibited development of tolerance to hypothermia. These results suggest that MK-801 inhibited contextual sensitization to climbing behavior and development of tolerance to hypothermia through glutamatergic modulation of dopaminergic functions at dopamine receptors.
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PMID:Inhibitory effects of MK-801 on contextual sensitization to climbing behavior and on development of tolerance to hypothermia induced by a single high dose of apomorphine. 1173 53

Dopamine constitutes about 80% of the content of central catecholamines and has a crucial role in the etiology of several neuropsychiatric disorders, including Parkinson's disease, depression and schizophrenia. Several dopaminergic drugs are used to treat these pathologies, but many problems are attributed to these therapies. Within this context, the search for new more efficient dopaminergic agents with less adverse effects represents a vast research field. The aim of the present study was to report the structural design of two N-phenylpiperazine derivatives, compound 4: 1-[1-(4-chlorophenyl)-1H-4-pyrazolylmethyl]-4-phenylhexahydropyrazine and compound 5: 1-[1-(4-chlorophenyl)-1H-1,2,3-triazol-4-ylmethyl]-4-phenylhexahydropyrazine, planned to be dopamine ligands, and their dopaminergic action profile. The two compounds were assayed (dose range of 15-40 mg/kg) in three experimental models: 1) blockade of amphetamine (30 mg/kg, ip)-induced stereotypy in rats; 2) the catalepsy test in mice, and 3) apomorphine (1 mg/kg, ip)-induced hypothermia in mice. Both derivatives induced cataleptic behavior (40 mg/kg, ip) and a hypothermic response (30 mg/kg, ip) which was not prevented by haloperidol (0.5 mg/kg, ip). Compound 5 (30 mg/kg, ip) also presented a synergistic hypothermic effect with apomorphine (1 mg/kg, ip). Only compound 4 (30 mg/kg, ip) significantly blocked the amphetamine-induced stereotypy in rats. The N-phenylpiperazine derivatives 4 and 5 seem to have a peculiar profile of action on dopaminergic functions. On the basis of the results of catalepsy and amphetamine-induced stereotypy, the compounds demonstrated an inhibitory effect on dopaminergic behaviors. However, their hypothermic effect is compatible with the stimulation of dopaminergic function which seems not to be mediated by D2/D3 receptors.
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PMID:Dopaminergic profile of new heterocyclic N-phenylpiperazine derivatives. 1271 82

Dopamine is a thermoregulatory neurotransmitter that provokes hypothermia when injected in or near the hypothalamus. Doxapram stimulates release of dopamine from carotid bodies, but is known to have central effects that are probably, at least in part, similarly mediated. We thus tested the hypothesis that doxapram produces a substantial, dose-dependent reduction in the shivering threshold in rabbits. Twenty-four rabbits, anesthetized with isoflurane, were randomly assigned to 1) saline (control), 2) 0.25 mg x kg(-1) x h(-1) doxapram, or 3) 0.50 mg x kg(-1) x h(-1) doxapram. These doses are within the recommended range for humans. Body temperature was reduced at a rate of 2 degrees to 3 degrees C/h by perfusing water at 10 degrees C through a U-shaped thermode positioned in the colon. Core temperatures were recorded from the distal esophagus. A blinded observer evaluated shivering. Core temperature at the onset of shivering defined the threshold. Data were analyzed with a one-way analysis of variance; P < 0.05 was considered statistically significant. Hemodynamic and respiratory responses were comparable in the groups. The control rabbits shivered at 36.3 degrees +/- 0.3 degrees C, those given 0.25 mg x kg(-1) x h(-1) doxapram shivered at 34.8 degrees +/- 0.5 degrees C, and those given 0.50 mg x kg(-1) x h(-1) shivered at 33.7 degrees +/- 0.6 degrees C. All the shivering thresholds significantly (P < 0.001) differed from one another. The magnitude of this inhibition, if similar in humans, would be clinically important.
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PMID:Doxapram produces a dose-dependent reduction in the shivering threshold in rabbits. 1293 97


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