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

Radiation-induced hypothermia was examined in guinea pigs. Exposure to the head alone or whole-body irradiation induced hypothermia, whereas exposure of the body alone produced a small insignificant response. Systemic injection of disodium cromoglycate (a mast cell stabilizer) and cimetidine (H2-receptor antagonist) had no effect on radiation-induced hypothermia, whereas systemic and central administration of mepyramine (H1-receptor antagonist) or central administration of disodium cromoglycate or cimetidine attenuated it, indicating the involvement of central histamine through both H1 and H2 receptors in this response. Serotonin is not involved, since the serotonin antagonist methysergide had no effect on radiation-induced hypothermia. These results indicate that central histaminergic systems may be involved in radiation-induced hypothermia.
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PMID:Involvement of histamine H1 and H2 receptors in hypothermia induced by ionizing radiation in guinea pigs. 312 32

The potent, centrally acting 5-HT receptor agonist 8-OH-DPAT was shown to induce a clearcut hypothermic response in naive and PCPA-pretreated conscious rats, maintained at 22 degrees C. PCPA pretreatment decreased the threshold dose of 8-OH-DPAT required to cause hypothermia, indicating that a sensitisation of 5-HT-receptor dependent mechanisms was involved. The results are discussed with reference to recent 5-HT receptor subclassification. It is suggested that body temperature measurements in the rat might provide a simple in vivo physiological means of studying central serotoninergic mechanisms, including 5-HT receptor sensitivity modification.
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PMID:Hypothermia in the rat induced by the potent serotoninergic agent 8-OH-DPAT. 315 65

The hypothermia elicited in mice by intracerebroventricular injection (i.c.v.) of serotonin (5-HT) was studied. The 5-HT-induced hypothermia was attenuated by methysergide and pindolol, although ketanserin and p-chlorophenylalanine were without effect. These results suggest that 5-HT-induced hypothermia is produced by the direct activation of the 5-HT1 receptor. In addition, haloperidol, pimozide and alpha-MT inhibited 5-HT-induced hypothermia, which indicates that the dopaminergic systems are also involved in 5-HT-induced hypothermia in mice.
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PMID:The involvement of serotonergic and dopaminergic systems in hypothermia induced in mice by intracerebroventricular injection of serotonin. 319 3

The study investigated the possible interrelationship between changes in sleep-wakefulness and body temperature, primarily induced by manipulation of the noradrenergic system in the medial preoptic area. Saline, norepinephrine, and its alpha- and beta-blockers were injected in the medial preoptic area and in some control areas of rats, during their sleeping and active periods. 5-Hydroxytryptamine was injected in the medial preoptic area in another group of animals. Simultaneous changes in sleep-wakefulness and the body temperature were continuously recorded. Norepinephrine produced hypothermia and arousal, whereas alpha-adrenergic blockers induced hyperthermia and sleep. These changes in body temperature and in sleep-wakefulness did not follow an identical time course. 5-Hydroxytryptamine induced hyperthermia without affecting sleep-wakefulness. It is suggested that there are different neuronal mechanisms in the medial preoptic area that bring about the drug-induced changes in temperature and sleep-wakefulness.
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PMID:Interrelationship of thermal and sleep-wakefulness changes elicited from the medial preoptic area in rats. 335 96

The circumscribed effect of ethyl alcohol on the local efflux of serotonin (5-HT) within the thermosensitive region of the anterior hypothalamic, pre-optic area (AH/POA) of the unrestrained rat was examined in relation to core temperature. A single guide cannula for push-pull perfusion was implanted stereotaxically in the AH/POA within coronal planes AP 7.0-8.2. Following 3-4 push-pull perfusions with control artificial CSF of a site identified as reactive to 5-HT, ethanol in a concentration of 2.75 (471 mM) or 5.5 (942 mM) percent was perfused at the same locus over a 5-10 min interval. Successive samples of perfusate were assayed for their content of 5-HT by high performance liquid chromatography using electrochemical detection (HPLC-EC). Within a circumscribed region of the AH/POA of the rat maintained at an ambient temperature of 22 degrees C, ethanol induced either an immediate or delayed hypothermia of short latency or a transient decline followed by an immediate increase in core temperature. In each case, the shift in temperature depended on the anatomical site of push-pull perfusion. Overall, the fall in core temperature was accompanied by an inhibition in the efflux of 5-HT. However, the consequent rise in the rat's core temperature was associated with an enhanced release of 5-HT in the samples of perfusate collected from the AH/POA. These results suggest that serotonergic synapses within the AH/POA are apparently involved in the thermolytic effects of ethanol as well as in the thermogenesis following the interval of heat loss.
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PMID:Temperature-related release of serotonin from unrestrained rats' pre-optic area perfused with ethanol. 341 63

We have investigated the ability of three hyperthermic stimuli (PGE2, 5-HT and ACh) to elicit hyperthermia in the Helium-Cold (He-Cold) hypothermic hamster. Hamsters in these conditions are poikilothermic and will passively follow room temperature in a regulated cold room. Animals were injected centrally at AH/POA sites via an indwelling guide tube at body temperatures maintained between 9-12 degrees C. Active sites in the AH/POA were determined prior to the experiment by PGE2 injection. PGE2 injection at an effective AH/POA site immediately reversed the anesthetic induced hypothermia in warm air. Hamsters were induced into hypothermia by the He-Cold induction method and body temperatures were maintained in a 9 degrees C cold room. Colonic temperatures were monitored at 5 minute intervals by a YSI thermistor probe and telethermometer. Central injections of 5-HT (2 micrograms/microliter) and ACh (50 micrograms/microliter) at effective AH/POA sites evoked significant increases in colonic temperature in He-Cold hamsters. PGE2 injections were not different from saline control injections and did not elicit pronounced temperature changes in these animals. Specific blockade of the 5-HT and ACh temperature increases was demonstrated with specific antagonist injections. The results suggest that the central organization of heat-gain mechanisms in the AH/POA is the same as normothermic animals even at temperatures well below those previously investigated.
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PMID:Organization of central hyperthermic mechanisms in helium-cold hypothermic hamsters. 346 74

The involvement of serotonin2 (5-HT2) receptors in the expression of opiate withdrawal was examined using a behavioral test for acute morphine dependence. The 5-HT2 antagonists, ketanserin and pirenperone, injected shortly before naloxone, attenuated the naloxone-induced suppression of an autoshaped lever-touch response in rats treated 4 h earlier with a moderate dose of morphine. A low dose of pirenperone was also effective in blocking withdrawal-induced hypothermia. These data support the hypothesis that 5-HT is involved in the expression of opiate withdrawal.
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PMID:Ketanserin and pirenperone attenuate acute morphine withdrawal in rats. 381 79

Hamsters in deep experimentally induced hypothermia, at body temperatures between 7 degrees C and 11.5 degrees C, were microinjected with 5-HT and ACh at brain sites in the anterior-preoptic area of the hypothalamus (AH/POA). ACh or 5-HT was injected into an AH/POA site at different starting core temperatures in different groups of hypothermic hamsters. Colonic temperatures (Tc) were maintained, following He-Cold induction, in a temperature controlled environmental chamber and measured with a YSI thermister probe and YSI telethermometer. Injections of either 5-HT or ACh at Tc's between 7.0 degrees C and 9.0 degrees C elicited only modest increases in Tc i.e., 0.3 degrees C--0.6 degrees C, respectively. As Tc increased, however, to ranges between 9.1 degrees C--10.0 degrees C and in different animals to greater than 10 degrees C both ACh and 5-HT at the same sites elicited significant increases in Tc, 1.5 degrees C for 5-HT and 2.2 degrees C for ACh compared to saline injections. These data suggest that at the lowest Tc's we are observing a "cold block" of temperature sensitive sites in the AH/POA. Increasing the starting Tc beyond 9.0 degrees C however, evokes significant increases in heat-gain following AH/POA injection of either ACh or 5-HT. These data are consistent with Myers' observations concerning the organization of heat-gain mechanisms at AH/POA sites. In addition, they suggest that both the afferent limb of the heat-gain circuit (5-HT) and the efferent limb of the circuit (ACh) are functionally impaired when Tc is close to the physiological limit in the He-Cold hypothermic hamster.
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PMID:ACh and 5-HT stimulated thermogenesis at different core temperatures in the He-Cold hypothermic hamster. 386 62

The results of studies of condensation of 1-(4,4-dimethyl-2-piperidon-6-yl)-4-phenyl-3-buten-2-one and its derivatives substituted in the benzene ring (R = 4-CH3 and R = 4-Cl) with hydrazine and its methyl or phenyl derivative are described. Compounds 2a, 2c and 2g were tested for their possible action on the central nervous system. Two drugs: 2c and 2g decreased locomotor activity. None of the examined compounds inhibited the reserpine-induced hypothermia, 5-HT syndrome and convulsions induced by pentetrazole in mice. Compound 2c injected only intraperitoneally depressed the number of the writhing episodes induced by p-phenylbenzoquinone.
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PMID:Synthesis of 3-(4,4-dimethyl-2-piperidon-6-yl)methyl-2-pyrazoline derivatives. 387 37

Norepinephrine, serotonin, and bombesin administered intrahypothalamically affected thermoregulation in the deermouse, Peromyscus maniculatus. At a Ta of 22 degrees C, doses of 3 micrograms and 6 micrograms of NE resulted in transient hypothermia (maximum drop of 1.6 +/- 1.0 degrees C and 4.3 +/- 2.3 degrees C, respectively). A 1.5 microgram dose of 5-HT induced a persistent hyperthermia (maximum increase of 1.8 +/- 0.8 degrees C) which persisted for more than 2 h. A 6 microgram dose of 5-HT did not produce any significant effects. At a Ta of 22 degrees C, doses of 1 ng and 10 ng of bombesin produced a transient hyperthermia (maximum increase of 1.8 +/- 0.3 degree C and 2.1 +/- 1.2 degrees C, respectively) immediately postinjection. At a Ta of 5 degrees C, a 1 ng dose of bombesin resulted in a prolonged hypothermia (maximum decrease of 2.0 +/- 0.4 degrees C), while a 10 ng dose of bombesin produced a hyperthermic response (maximum increase of 1.3 +/- 0.8 degree C) at 2 h postinjection.
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PMID:Effects of intrahypothalamically administered norepinephrine, serotonin and bombesin on thermoregulation in the deermouse (Peromyscus maniculatus). 394 67


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