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

The effects of developmental age on (+/-)-3,4-methylenedioxymethamphetamine (MDMA)-induced reductions in 5-hydroxytryptamine (5-HT) content and 5-HT reuptake sites were investigated in conjunction with the effects of developmental age on MDMA-induced thermoregulatory responses. MDMA was administered to rats at postnatal days (PND) 10, 40 and 70 in a range of ambient temperature environments (10 degrees C, 25 degrees C and 33 degrees C). Animals were monitored for alterations in body temperature and sacrificed 1 week after MDMA administration. MDMA administration at PND 10 did not result in persistent reductions in 5-HT content or 5-HT reuptake sites in frontal cortex, nor could a hyperthermic response be elicited. In contrast, MDMA administration at PND 40 and PND 70 resulted in a hypothermic response in cold environments (10 degrees C) and a hyperthermic response in warm environments (> or = 25 degrees C). When hypothermia was observed after MDMA (10 degrees C environment), long-term reductions in 5-HT content and 5-HT reuptake sites were significantly attenuated or abolished. Conversely, when a hyperthermic response was observed (25 degrees C and 33 degrees C environments), long-term MDMA-induced reductions in 5-HT content and 5-HT reuptake sites were significantly enhanced. Thus, thermal responses significantly correlated with MDMA-induced reductions in 5-HT content and 5-HT reuptake sites. These experiments demonstrate a role for hyperthermia in the expression of serotonergic neurotoxicity after MDMA administration.
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PMID:Age-dependent sensitivity of rats to the long-term effects of the serotonergic neurotoxicant (+/-)-3,4-methylenedioxymethamphetamine (MDMA) correlates with the magnitude of the MDMA-induced thermal response. 756 67

1. The study was carried out in adult patients having normal cardiovascular reflexes and no brain stem lesions. They were exposed to ambient temperature of 72-74 degrees F. Injections of agonists and antagonists of receptors were made into the lateral cerebral ventricles of these patients through diagnostic burr hole in the skull. 2. Noradrenaline, adrenaline and dopamine evoked hypotension and bradycardia. While the core temperature was reduced by nor-adrenaline and adrenaline, dopamine evoked hyperthermia. Isoprenaline elicited hypertension, tachycardia and hyperthermia. Opposite cardiovascular and thermal effects were observed with blockade of alpha 1-, beta-and dopamine receptors with prazosin, propranolol and haloperidol respectively. 3. Injection of 5-hydroxytryptamine resulted in hypertension, tachycardia and hyperthermia but hypotension, bradycardia and hypothermia were seen with methysergide. 4. Similarly, carbachol injection caused initial excitatory followed by inhibitory cardiovascular responses. These were associated with hypothermia. On the contrary atropine per se elicited hypertension, tachycardia and hyperthermia. 5. Thus, alpha 1- and beta-adrenoceptors, dopaminergic, serotonergic and muscarinic cholinergic receptors are present in human brain which appear to modulate cardiovascular activity and core temperature.
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PMID:A study of effects of putative neurotransmitters injected into the lateral cerebral ventricle of man. 790 93

1. The hydroxylated metabolites of amphetamine, p-hydroxyamphetamine (p-OHA) and p-hydroxynorephedrine (p-OHN), were administered intracerebroventricularly in mice in order to evaluate their ability to elicit hypothermia. 2. Intracerebroventricular (i.c.v.) administration of p-OHA and p-OHN (1, 3 and 9 micrograms/mouse) induced maximal hypothermia 30 min after injection. p-OHA and p-OHN (9 micrograms, i.c.v.) produced maximal decreases in rectal temperature of -6.48 +/- 0.44 degrees C and -3.82 +/- 0.42 degrees C, respectively. Both metabolites are more effective than amphetamine (at 9 micrograms, i.c.v., -3.32 +/- 0.75 degrees C). 3. Pretreatment with haloperidol (5 micrograms, i.c.v.) suppressed the fall in temperature produced by p-OHA (3 micrograms, i.c.v.) and reduced that produced by p-OHN (3 micrograms, i.c.v.), respectively. The selective dopaminergic D1 receptor antagonist, SCH 23390, and the D2 receptor antagonists, sultopride and metoclopramide, were without effect on the hypothermia induced by either metabolite. Similarly, amphetamine-induced hypothermia was only inhibited by haloperidol. Apomorphine (0.1 mg kg-1, i.p.) did not potentiate the hypothermia induced by either metabolite, whereas the selective dopaminergic D2 agonist, quinpirole (0.2 mg kg-1, i.p.) did. Amphetamine-induced hypothermia was potentiated by apomorphine and quinpirole. 4. Neither the 5-hydroxytryptamine (5-HT) receptor blocker, cyproheptadine, nor the 5-HT receptor agonist, quipazine, modified metabolite-induced hypothermia. In contrast, amphetamine-induced hypothermia was affected by these 5-HT drugs. 5. The neuropeptide CCK-8 (0.04 mg kg-1, i.p.) and gamma-butyrolactone (40 mg kg-1, i.p.) potentiated the hypothermia produced by amphetamine and its metabolites. Conversely, desipramine (20 mg kg-1, i.p.) antagonized it.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Involvement of hydroxylated metabolites in amphetamine-induced hypothermia in mice. 809 41

The inhibitory effect of nicotine pretreatment on reserpine-induced depletion of monoamines in mouse brain was investigated. The depletion of brain monoamines by 24 h after intraperitoneal injection of reserpine (2 mg/kg) was dose-dependently inhibited by nicotine (0.3-10 mg/kg, s.c.) pretreatment 20 min before reserpine injection. This effect of nicotine was more marked on dopamine depletion than on noradrenaline or 5-hydroxytryptamine depletion. The nicotine pretreatment also inhibited the reserpine-induced hypothermia and decrease in the locomotor activity. When reserpine (2 mg/kg) was injected intraperitoneally, the inhibitory effect of nicotine (3 mg/kg, s.c.) on the reserpine-induced depletion of brain monoamines and heart noradrenaline was not antagonized by hexamethonium (8 mg/kg, s.c.) but rather potentiated by mecamylamine (2 mg/kg, s.c.). However, when reserpine (0.5 mg/kg) was injected intravenously, pretreatment with nicotine (3 mg/kg, s.c.) inhibited the reserpine-induced dopamine depletion only, and this effect of nicotine was completely blocked by mecamylamine but not by hexamethonium. These results suggest that inhibitory effect of nicotine on the intraperitoneal reserpine-induced depletion of brain monoamines is due to an inhibition of absorption of reserpine, and that central nicotinic action is also involved in the antagonism by nicotine of reserpine-induced dopamine depletion.
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PMID:Possible explanations for the antagonism by nicotine against reserpine-induced depletion of monoamines in mouse brain. 823 94

The i.p. administration of 1-methyl-4-(2'-aminophenyl)-1,2,3,6-tetrahydropyridine (2'-NH2-MPTP; 4 x 20 mg/kg) to Swiss Webster mice caused substantial decreases in cortical and hippocampal 5-hydroxytryptamine (5-HT), 5-hydroxyindoleacetic acid and norepinephrine (NE) measured 1 week post-treatment. Compared with the authors' previously reported results in C57BL/6 mice, these effects were significantly greater in hippocampus (80-90% vs. 60%) and of a similar magnitude in frontal cortex (60-75%). A long-term study showed that cortical and hippocampal 5-HT, 5-hydroxyindoleacetic acid and NE were still decreased 40% to 50% 6 months after treatment. Regional brain dopamine was essentially unchanged during the 6-month period. Pretreatment with the 5-HT-selective uptake inhibitors, fluoxetine or paroxetine, or with the NE-selective uptake inhibitor, desipramine, prevented decreases in cortical and hippocampal 5-HT and NE, respectively, 3 weeks after 2'-NH2-MPTP (4 x 20 mg/kg). In addition, pretreatment with the monoamine oxidase type-A inhibitor, clorgyline, also prevented the more modest decreases in 5-HT and NE caused by 4 x 15 mg/kg 2'-NH2-MPTP. Selegiline, a monoamine oxidase-B inhibitor, did not provide similar protection. Lastly, 2'-NH2-MPTP administered 3 weeks earlier, abolished hypothermia caused by the serotonin agonist, m-chlorophenylpiperazine, which provided preliminary evidence for an associated functional change in the central serotonergic system. Together, these data suggest that 2'-NH2-MPTP is a novel agent capable of producing long-lasting depletions in forebrain 5-HT and NE but not dopamine in two different strains of mice by some mechanisms that resemble those of the parent dopamine-depleting neurotoxin, MPTP.
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PMID:2'-NH2-MPTP in Swiss Webster mice: evidence for long-term (6-month) depletions in cortical and hippocampal serotonin and norepinephrine, differential protection by selective uptake inhibitors or clorgyline and functional changes in central serotonin neurotransmission. 826 5

The effect of chronic treatment (5 and 10 mg/kg i.p., twice daily, 14 days) with fluoxetine (FLU), an antidepressant drug which selectively inhibits the reuptake of 5-hydroxytryptamine (5-HT), on the responsiveness of 5-HT receptor subpopulations to their agonists in rats and mice was examined. FLU had no effect on the hypothermia (in mice) and the behavioural syndrome (in rats) induced by 8-OH-DPAT (a 5-HT1A agonist). The m-CPP-induced hypothermia in mice (a 5-HT1B effect) was increased by FLU given chronically. FLU in a single dose decreased that effect. FLU given chronically attenuated the m-CPP-induced hypoactivity in rats (a 5-HT1C effect). The effects mediated by 5-HT2 receptors (L-5-HTP-induced head twitches in mice; fenfluramine-, m-CPP- and TFMPP-induced hyperthermias in rats) were reduced by chronic FLU. The above results indicate that FLU given chronically has no effect on the responsiveness of 5-HT1A receptors, increases the responsiveness of 5-HT1B receptors and decreases those of 5-HT1C and 5-HT2 receptors.
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PMID:Effects of fluoxetine given chronically on the responsiveness of 5-HT receptor subpopulations to their agonists. 836 53

The present study investigated the change in thermoregulatory responses following microinjection of 5-hydroxytryptamine (5-HT) into the lateral septum and the hippocampus of unanesthetized, unrestrained rats. Intraseptal injection of 5-HT (5 to 20 micrograms) caused a dose-related fall in core temperature (Tb), which was associated with a decrease in heat production (HP). As the decrease in HP can not completely account for the magnitude of the decrease in Tb, increase in heat loss may also be involved in the 5-HT-induced hypothermia. In contrast to observed changes following intraseptal injection, no significant change in either Tb or HP was observed after microinjection of the same doses of 5-HT into the hippocampal areas, indicating that the hypothermic response to intraseptal injection of 5-HT is site specific. Further, the hypothermic response to intraseptal injection of 5-HT was only attenuated by systemic pretreatment with cyproheptadine, but not by naloxone or scopolamine, indicating that the hypothermic response is mediated by 5-HT receptor, but not by endogenous opioid and cholinergic systems.
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PMID:Thermoregulatory responses following injection of 5-hydroxytryptamine into the septohippocampal complex in rats. 841 34

In this study, we examined the localization of the 5-hydroxytryptamine (5-HT)1A receptors mediating hypothermia in the rat, evaluated the pharmacological specificity of this response and examined the influence of a series of novel 5-HT1A receptor ligands upon core temperature. Administered s.c., 8-hydroxy-(2-di-n-propylamino)tetralin hydrobromide (8-OH-DPAT), an agonist at both pre- and postsynaptic 5-HT1A receptors, elicited pronounced hypothermia. In contrast, BMY 7378, which shows low efficacy at postsynaptic 5-HT1A receptors but high efficacy at presynaptic 5-HT1A receptors, elicited only mild hypothermia. Similarly, 8-OH-DPAT was more efficacious than BMY 7378 in eliciting corticosterone secretion, a response mediated by postsynaptic 5-HT1A receptors, whereas BMY 7378 was as efficacious as 8-OH-DPAT in inhibiting striatal accumulation of 5-hydroxytryptophan, a response mediated by presynaptic 5-HT1A receptors. These data suggest, by analogy, that postsynaptic 5-HT1A receptors mediate hypothermia, an interpretation supported by the observation that destruction of central 5-HT neurons with 5,7-dihydroxytryptamine failed to reduce 8-OH-DPAT-induced hypothermia (DIH). Agonists at 5-HT1B, 5-HT1C, 5-HT2 and/or 5-HT3 receptors did not elicit hypothermia, and drugs releasing 5-HT elicited hyperthermia. In contrast, DIH was fully mimicked by the novel 5-HT1A receptors agonists, eltoprazine, WY 48,723, MDL 72832, tandospirone, S 14671, S 14506 and WY 50,324, whereas the novel partial agonist, zalospirone, was less efficacious. DIH was blocked by (-)-alprenolol, (+/-)-pindolol and the novel beta-blocker, (-)-tertatolol, which also has high affinity for 5-HT1A receptors; in distinction, betaxolol and ICI 118,551, antagonists at beta-1 and beta-2 adrenoceptors, respectively, were inactive. Spiperone, NAN-190 and BMY 7378 also inhibited DIH whereas ritanserin, SCH 39166, raclopride and prazosin, antagonists at 5-HT2 receptors, D1 and D2 dopamine receptors and alpha-1 adrenoceptors, respectively, were inactive. The novel 5-HT1A antagonists, WAY 100,135, MDL 73005 EF and (very potently) SDZ 216-525 all blocked DIH. Potency for induction of hypothermia and inhibition of DIH correlated well with affinity for 5-HT1A binding sites. In conclusion, hypothermia is a highly specific and sensitive response to activation of postsynaptic 5-HT1A receptors. Furthermore, DIH is inhibited by their selective blockade. At postsynaptic 5-HT1A receptors mediating hypothermia, eltoprazine, WY 48,723, MDL 72832 and tandospirone are agonists, zalospirone is a partial agonist and (-)-tertatolol, WAY 100,135, MDL 73005 EF and SDZ 216-525 are antagonists.
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PMID:Induction of hypothermia as a model of 5-hydroxytryptamine1A receptor-mediated activity in the rat: a pharmacological characterization of the actions of novel agonists and antagonists. 845 Apr 71

1. The 5-hydroxytryptamine (5-HT)1A agonist 8-hydroxy-2-(dipropylamino)tetralin (8-OH-DPAT) has been evaluated in a mouse model for detecting potential antidepressants (Porsolt test). The effects of various receptor antagonists, lesions of brain monoaminergic neurones and chronic drug treatments on this 8-OH-DPAT-induced response have also been determined. 2. 8-OH-DPAT (0.3-10.0 mg kg-1, s.c.) dose-dependently increased the mobility of mice in the Porsolt test. Other selective 5-HT1A receptor ligands (0.3-30 mg kg-1, s.c.) either mimicked the 8-OH-DPAT response (ipsapirone, at 10 and 30 mg kg-1, s.c.) or were inactive (buspirone and gepirone). However, each of these compounds (< or = 100 mg kg-1, p.o.) inhibited the response to 8-OH-DPAT (3 mg kg-1, s.c.) when given concurrently. 3. The putative 5-HT1A antagonists, spiroxatrine (1-30 mg kg-1, p.o.), (+/-)-pindolol (30 mg kg-1, p.o.) and methiothepin (3-10 mg kg-1, p.o.), each attenuated the 8-OH-DPAT (3 mg kg-1, s.c.)-induced increase in mobility. 4. The dopamine D1 receptor antagonist, SCH 23390 (3-10 mg kg-1, p.o.), weakly reversed the 8-OH-DPAT response. Antagonists at 5-HTlc/5-HT2 receptors (ketanserin; 0.1-3.0 mg kg-1, p.o.),5-HT3 receptors (ondansetron; 0.03-10mg kg-1, p.o.), at-adrenoceptors (prazosin; 1-3mgkg-1, p.o.),alpha2 -adrenoceptors (idazoxan; 3-30mg kg-1, p.o.), alpha 1-adrenoceptors (metoprolol; 1-30mgkg-1, p.o.),beta 2-adrenoceptors (ICI 118,551; 1-30 mg kg-1, p.o.), dopamine D2 receptors (sulpiride; 10-300mg kg-',p.o.) and opiate receptors (naloxone; 3-100 mg kg-', p.o.) had no effect on the 8-OH-DPAT response.5. Selective destruction of 5-HT neurones with 5,7-dihydroxytryptamine or inhibition of 5-HT synthesis with p-chlorophenylalanine did not change the 8-OH-DPAT response in the Porsolt test. This response was also unaltered by pretreatment with the noradrenergic neurotoxin, DSP-4.6. Administration of 8-OH-DPAT (3 mg kg-1, s.c.) twice-daily for 10 days attenuated the hypothermia,but not the increased mobility, induced by 8-OH-DPAT (3 mg kg-1, s.c.). Similarly, repeated administration of amitriptyline (3-30 mg kg-1), desipramine (3-30 mg kg-1) or dothiepin (10-100 mg kg-1) also attenuated the former, but not the latter, response.7. We conclude that 8-OH-DPAT produces an antidepressant-like effect in the Porsolt test which is mediated via postsynaptic 5-HT1A receptors.
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PMID:Mediation of the antidepressant-like effect of 8-OH-DPAT in mice by postsynaptic 5-HT1A receptors. 846 55

(+/-)3,4-methylenedioxymethamphetamine (MDMA; "Ecstasy"), an increasingly popular recreational drug, is known to damage brain serotonin (5-hydroxytryptamine [5-HT]) neurons, whilst also having a less pronounced effect on the dopaminergic system. Treatment with MDMA results in an increased locomotor activity, elevated basal serum corticosterone concentrations, decreased exploratory activity, and changes in body temperature. The aim of this study was to examine the dose related effects of subacute administration of MDMA (5, 10, and 20 mg/kg IP twice daily for 4 days) on home cage locomotor activity, "open field" and "step-down passive avoidance" behaviours, changes due to an 8-hydroxy-2-(di-n-propylamino)-tetralin (8-OH-DPAT) challenge, and on plasma corticosterone and brain neurotransmitter concentrations. Total locomotor activity counts were significantly increased by both 10 and 20 mg/kg MDMA for the 4 days of drug administration. There were no significant differences seen in the "open field" or "step down passive avoidance" behaviour, in the 8-OH-DPAT induced hypothermia, or in basal serum corticosterone concentrations. MDMA caused a significant depletion of both 5-HT and 5-hydroxyindoleacetic acid (5-HIAA) in the frontal cortex and amygdala and a significant elevation of dopamine and noradrenaline in the hippocampus. Apart from the increase in locomotor activity following subacute administration, the observed behaviour of the MDMA treated rats would not appear to reflect the substantial changes in brain biogenic amine neurotransmitters.
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PMID:Some behavioural and neurochemical aspects of subacute (+/-)3,4-methylenedioxymethamphetamine administration in rats. 854 62


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