Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0020672 (hypothermia)
 17,327 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The tremorogenic properties of a series of benzylimidoylurea derivatives are described. The most potent member, N-carbamoyl-2-(2,6-dichlorophenyl) acetamidine hydrochloride (LON-954), produces a reproducible, dose-dependent rest tremor in the mouse with oral doses of 5-100 mg/kg which is also seen in other species (rat, cat, dog, rabbit). The tremor is of constant frequency, rapid onset and short duration. It is not accompanied by akinesia, muscle ridigity, antinociceptive activity, parasympathomimetic effects or marked hypothermia and in these respects differs from tremor produced by oxotremorine. Pretreatment with a microsomal enzyme inhibitor had no effect on the tremor. An LD50 of 165 mg/kg p.o. was calculated in the mouse. After repeated administration both acute and chronic tolerance developed to the tremorogenic effects of LON-954. Evidence for a central site of action is presented, since the tremor could be reproduced following injection of small quantities (50-100 microgram) into the cerebral ventricles of the mouse. Furthermore, the use of spinal, decorticate and and decerebrate rats indicated that although tremor is not of cortical origin, it arises in an area rostral to the inferior colliculi. The mechanism underlying the tremor appears to involve dopaminergic pathways, since the action of LON-954 was antagonised by L-dopa and apomorphine and potentiated by pimozide. Atropine and carbachol were without effect. It is suggested that LON-954 could be used as an alternative to oxotremorine for the detection of anti-Parkinson drugs, particularly those exerting their effects through dopaminergic mechanisms.
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PMID:The pharmacology of N-carbamoyl-2-(2,6-dichlorophenyl)acetamidine hydrochloride (LON-954) a new tremorogenic agent. 58 44

1. In unanaesthetized pigeons the effect on cloacal temperature was studied of acetylcholine (ACh), carbachol, atropine and (+)-tubocurarine injected into a cannulated lateral cerebral ventricle. The experiments were carried out at an ambient temperature of 19-25 degrees C. 2. ACh or carbachol injected intraventricularly produced hyperthermia, and in larger doses hyperthermia followed by hypothermia. These were central effects because they were not obtained when these drugs were injected in the same doses intravenously. 3. Atropine injected intraventricularly produced hypothermia which was greater and longer lasting than the hypothermia produced with the same dose of atropine injected intravenously. After the intraventricular injection of atropine the hyperthermic effects of ACh and of carbachol were abolished. 4. (+)-Tubocurarine injected intraventricularly produced a long-lasting hyperthermia in doses which had no effect on temperature when injected intravenously. After the intraventricular injection of tubocurarine the hypothermic effects of ACh and of carbachol were abolished. 5. It is concluded that the effects of ACh had carbachol imitate the effects of ACh released from cholinergic neurones in the central pathway involved in temperature regulation. The hypothermic effect of atropine is attributed to unmasking the activity of continuously released ACh acting on nicotinic receptors, and the hyperthermic effect of tubocurarine to unmasking the activity of continuously released ACh acting on muscarinic receptors.
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PMID:Cholinergic mechanisms in central thermoregulation in pigeons. 113 26

1 The mechanism of the cataleptic effect of metoclopramide was analyzed by using drugs which alter the activity of dopaminergic or cholinergic neurones or the content of psi-aminobutyric acid in the central nervous system of rats. 2 The cataleptic effect of metoclopramide (20 mg/kg) was antagonized by apomorphine (10 mg/kg) and by atropine (50 mg/kg). Aminoxyacete acid (AOAA, 25-50 mg/kg) potentiated the catalepsy induced by metoclopramide (5 mg/kg). 3 Metoclopramide alone did not alter the rectal temperature of rats. It did not alter the AOAA-induced hypothermia, but it partially antagonized apomorphine-induced hypothermia. 4 Metoclopramide induced a six-fold increase in striatal homovanillic acid (HVA) concentration, but it did not change the dopamine or noradrenaline content in the brain of rats. Apomorphine decreased the striatal HVA concentration in control and in metoclopramide-treated rats. Atropine and AOAA did not alter the metoclopramide-induced increase in striatal HVA concentration. 5 The results suggest that metoclopramide produces catalepsy by blocking striatal dopamine receptors.
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PMID:Inhibition by apomorphine of the metoclopramide-induced catalepsy and increase in striatal homovanillic acid content. 123 23

Sedative effects of medetomidine, a potent selective and specific alpha 2-adrenoceptor agonist, were evaluated in pigs using 5 different doses (30, 50, 80, 100 and 150 micrograms/kg of body weight) and compared with those of xylazine (2 mg/kg). Atropine (25 micrograms/kg) was mixed with both drugs to prevent severe bradycardia. All drugs were administered intramuscularly. Medetomidine at a dosage of 30 micrograms/kg produced more potent sedation than xylazine. The depth of sedation induced by medetomidine was dose dependent within the range from 30 to 80 micrograms/kg. At 100 or 150 micrograms/kg, the depth of sedation was mostly the similar level to that at 80 micrograms/kg but the duration was prolonged. The degree of muscle relaxation produced by medetomidine also seemed to be dose dependent from 30 to 80 micrograms/kg and was stronger than that produced by xylazine. An increase in the duration of muscle relaxation was dose dependent up to 150 micrograms/kg. No analgesic effect was produced by xylazine, however moderate analgesia was obtained by medetomidine. There were no marked changes in heart rate and respiratory rate during the observation period in pigs of any groups, however mild hypothermia after the administration of both drugs was observed. From these results, medetomidine has a significant and dose-dependent sedative effects which are much more potent than that of xylazine, and a combination of 80 micrograms/kg of medetomidine and 25 micrograms/kg of atropine is suitable for sedation with lateral recumbency and moderate muscle relaxation without notable side effects in pigs.
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PMID:Sedative effects of medetomidine in pigs. 139 Nov 73

Corticotropin-releasing factor (CRF) has been shown to reverse effect of pentobarbital (PbNa) within the central nervous system. In this study, the mechanism of the antagonistic effect of CRF on PbNa-induced anesthesia and hypothermia in rats was examined. Intraventricular administration of CRF significantly shortened sleeping time and antagonized hypothermia induced by PbNa. Propranolol (148 micrograms, 0.5 mumol), a beta-blocker, completely reversed the CRF effect, although propranolol alone affected neither sleeping time nor rectal temperature. Phentolamine, an alpha-blocker, reversed the antagonistic effect of CRF on PbNa, though the same dose of phentolamine alone increased the sleeping time in the absence of CRF. Atropine, an anticholinergic agent, did not affect the ability of CRF to reverse the effects of PbNa. These results suggest that the ability of CRF to reduce some of the effects of PbNa may be mediated at least in part by brain beta-noradrenergic receptors.
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PMID:Corticotropin-releasing factor reverses the effect of pentobarbital through a beta-noradrenergic mechanism in rats. 284 61

In a set of experiments designed to examine learned associations between drug states, atropine sulfate (10 mg/kg) elicited a conditional hyperthermia in rats following ten treatment sessions in which the drug was paired with either chlorpromazine hydrochloride (10 mg/kg) or ethanol (2.3 g/kg), both hypothermia-inducing agents. Atropine methyl nitrate, a quaternary analogue with similar peripheral effects but little central action, was ineffective as a cue in this situation. These experiments demonstrated that a sequential pairing of drug states can yield a change in an organism's response to the cue drug (the first drug in the sequence).
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PMID:Conditional hyperthermia in response to atropine associated with a hypothermic drug. 309 19

The effects of thyrotropin-releasing hormone (TRH) on brain temperature in response to pentobarbital were examined in male rats. After intraperitoneal injection of pentobarbital sodium (55 mg/kg body wt), the rats were fixed stereotaxically and received intraventricular (ivt) injection of varying doses (0.03-30 nmol) of TRH and 17 nmol atropine. Following the injection of 3 nmol TRH, 100 nmol of carbocholine was administered in the same manner. A thermocouple microprobe was unilaterally placed in the midbrain reticular formation so that brain temperature was continuously monitored at room temperature. Brain temperature after pentobarbital injection progressively decreased. While ivt injection of saline did not affect this change in temperature, ivt administration of TRH produced a dose-dependent antagonism of the brain hypothermia induced by pentobarbital. Atropine injection also reversed the pentobarbital-induced decrease in brain temperature. Carbocholine injection led to a significant decrease in brain temperature in response to TRH administration. The present study indicates that brain TRH may play a pivotal role in brain thermoregulation and its mechanism may involve at least in part the central cholinergic pathway in the rat.
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PMID:Antagonism by thyrotropin-releasing hormone of brain temperature in response to pentobarbital in the rat: possible involvement of cholinergic mechanism. 309 3

The mycotoxins cyclopiazonic acid (CPA) and ergotamine, and the neurotransmitter serotonin all have the beta-aminoethylindole moiety in common. These compounds enhanced the peristaltic movements of the jejunum, ileum and estrous uterus and produced broncho-constriction in vitro. Atropine and cyproheptadine were able to counter the CPA-induced peristaltic movements of the ileum and jejunum. L-epinephrine was able to stop the contractions induced by CPA on both estrous and pregnant rat uteri. Unlike chlorpromazine, CPA did not block the inotropic effects of dopamine, epinephrine and serotonin in vas deferens. This indicated that the previously reported toxic effects of CPA (hypothermia, catalepsy, hypokinesia, tremor) which resembled the effects of anti-psychotic drugs (chlorpromazine, reserpine) probably were not due to the blocking of the neurotransmitter-receptors. In contrast to ergotamine, which decreased the inotropic effects of serotonin on the uterus, CPA had no anti-serotonin effects. The uterotonic effect of CPA (similar to that of ergotamine) suggested that CPA also might have an adverse effect on the reproductive function of humans and animals consuming CPA-contaminated foods.
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PMID:Effects of cyclopiazonic acid on the contractility of organs with smooth muscles, and on frog ventricles. 348 54

Neurotensin (NT) and carbachol both caused hypothermia when injected into the periaqueductal grey area (PAG) of rat brain. Atropine prevented carbachol- but not NT-induced hypothermia. NT-induced hypothermia was unaffected by various neurotransmitter agonists and antagonists in the PAG. Both NT antibodies and thyrotrophin releasing hormone prevented carbachol hypothermia. It is concluded that the hypothermic action of carbachol in the PAG is mediated via endogenous NT.
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PMID:The hypothermic action of carbachol in the rat brain periaqueductal grey area may involve neurotensin. 374 53

1. An investigation of central cholinoceptors in the mouse has been made by injecting cholinomimetic drugs into the cerebral ventricles and seeing how their effects were modified by prior administration of atropine-like substances and other drugs.2. Carbachol or oxotremorine injected in small doses intracerebroventricularly into conscious mice caused hypothermia, gross tremor and a variety of parasympathomimetic effects including lachrymation and salivation. Acetylcholine injected in this way was active only in much larger doses.3. Methacholine and pilocarpine also caused a variety of parasympathomimetic effects after intracerebroventricular injection but virtually no hypothermia or tremor.4. Nicotine injected intracerebroventricularly caused mild hypothermia, fine tremor but no parasympathomimetic effects.5. Atropine-like drugs, tricyclic antidepressants and amphetamine antagonized the hypothermia induced by intracerebroventricular carbachol or oxotremorine.6. The sites of action of the atropine-like drugs are in the brain; those of the tricyclic antidepressants and amphetamine are in the periphery probably on heat generating beta-adrenoceptor mechanisms.7. It is concluded that the atropine sensitive cholinoceptors in the brain vary in their sensitivities to cholinomimetic drugs, other than acetylcholine, and may exist in isoreceptor forms.8. Peripheral atropine sensitive cholinoceptors may also exist in isoreceptor forms.
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PMID:Investigation of central cholinergic mechanisms in the conscious mouse. 558 Jun 97


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