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Results for “BODY TEMPERATURE REGULATION”

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At least 253 records · Page 14Linked to original sources
PubMed1987

The effects of ligation of the oesophagus on body and brain temperature in pigeons.

1. We measured brain and colonic temperatures in adult pigeons (Columba livia) with or without oesophageal ligation, and with or without simultaneous eye covering at ambient temperatures between 24 degrees C and 45 degrees C. 2. Colonic and brain temperatures rose at the higher ambient temperatures; the temperature elevations were no different in pigeons with oesophageal ligation, compared to sham-operated controls. The presence of simultaneous eye covering also had no effect on colonic or brain temperatures. 3. Oesophageal inflation decreased from a rate of 2.8 +/- 1.4 per minute (mean +/- SEM) to zero, in anaesthetized pigeons when warmed from a colonic temperature of 40.5 degrees C to 43.8 degrees C. 4. In pigeons oesophageal inflation plays no significant part in body temperature regulation or in the maintenance of a lower brain than body temperature even in hot ambient conditions.

Animals↗
PubMed2006

Melanin-concentrating hormone receptor 1 deficiency increases insulin sensitivity in obese leptin-deficient mice without affecting body weight.

The hypothalamic peptide melanin-concentrating hormone (MCH) plays important roles in energy homeostasis. Animals overexpressing MCH develop hyperphagia, obesity, and insulin resistance. In this study, mice lacking both the MCH receptor-1 (MCHr1 knockout) and leptin (ob/ob) double-null mice (MCHr1 knockout ob/ob) were generated to investigate whether the obesity and/or the insulin resistance linked to the obese phenotype of ob/ob mice was attenuated by ablation of the MCHr1 gene. In MCHr1 knockout ob/ob mice an oral glucose load resulted in a lower blood glucose response and markedly lower insulin levels compared with the ob/ob mice despite no differences in body weight, food intake, or energy expenditure. In addition, MCHr1 knockout ob/ob mice had higher locomotor activity and lean body mass, lower body fat mass, and altered body temperature regulation compared with ob/ob mice. In conclusion, MCHr1 is important for insulin sensitivity and/or secretion via a mechanism not dependent on decreased body weight.

Animals↗
PubMed1996

Relationship between drinking and increase in tail skin temperature of rats treated with L-5-hydroxytryptophan.

Administration of L-5-hydroxytryptophan (25 micrograms/kg, s.c.), the immediate precursor of serotonin, to rats induces drinking and increases tail skin temperature. Decreases in both the metabolic rate (rate of oxygen consumption) and colonic temperature also occur. These responses are similar to those observed following acute administration of angiotensin II. However, both drinking and the increase in tail skin temperature are unaffected by prior administration of the non-peptide angiotensin II, AT-1 receptor antagonist, losartan potassium, but are partially attenuated by the beta-adrenoceptor antagonist, propranolol. This suggests that the responses are independent of the angiotensin AT-1 receptor but may be mediated, in part at least, by the beta-adrenoceptor. The hypothesis is presented that when either L-5-hydroxytryptophan or angiotensin II is administered to rats, they act centrally to reduce the set-point for body temperature regulation, thus resulting in the reflex activation of mechanisms that reduce body temperature, including an increase in tail skin temperature and a decrease in metabolic rate.

5-Hydroxytryptophan↗
PubMed1989

Photoperiod and thermoregulation in vertebrates: body temperature rhythms and thermogenic acclimation.

Evidence has recently begun to accumulate that photoperiodic responses of mammals and birds may affect the control of energy balance and thermoregulation. Exposure to short photoperiod can lower the set point for body temperature regulation in birds and mammals, as well as the voluntarily selected body temperature in ectothermic lizards. This decrease is accompanied by a reorganization of circadian or ultradian rhythms of body temperature, particularly an increase in periods spent at rest with minimum body temperatures. Short photoperiod is also used as an environmental cue for induction of seasonal torpor or facilitation of hibernation. During winter, cold tolerance of small mammals is improved by an increase of nonshivering thermogenesis in brown fat. Thermogenic capacity of brown fat (respiratory enzymes, mitochondria, uncoupling protein) is enhanced in response to short photoperiod. This response is mediated via an increase in the activity of sympathetic innervation in brown fat. Moreover, an exposure to short photoperiod prior to low temperatures may act in preparing brown fat for facilitated thermogenesis during acclimation to cold. This shows that photoperiodic control not only affects energy balance indirectly via the control of reproduction or body mass, but may directly interact with central control of thermoregulation and may influence the process of acclimatization.

Activity Cycles↗
PubMed1982

Intracranial osmoreceptors control evaporation in the heat-stressed cat.

During heat stress, most mammals regulate body temperature by evaporating body water. Dehydrated mammals reduce their evaporative water losses and allow body temperature to rise. The physiological mechanism underlying this inhibition of evaporative cooling in dehydration have remained unclear. We now report that the rate of evaporation in dehydrated, heat-stressed cats is controlled by intracranial osmoreceptors and suggest that these receptors are part of a common central neural osmoreceptive mechanism regulating evaporative heat loss, renal water loss and thirst.

Animals↗
PubMed1979

Early mortality and temperature regulation in burned mice following administration of catecholamines and adrenergic receptor blocking drugs.

The effect of catecholamines and adrenergic receptor blocking drugs on mortality and body temperature was studied in mice subjected to burn, tourniquet, and endotoxin shock at an environmental temperature of 25 degrees C. Epinephrine and norepinephrine (0.5 mg/kg) injected intraperitoneally postburn increased shock mortality significantly (p less than 0.05); pretreatment with these catecholamines had no effect. Pretreatment of burn- and tourniquet-traumatized mice with propranolol (25 mg/kg) significantly decreased shock mortality, while pretreatment with dibenamine (25 mg/kg) significantly lowered early mortality after endotoxin. None of the catecholamines or their blocking drugs significantly prevented the characteristic immediate fall in core temperature after the three types of shock. At 6 days postburn, however, a combination of propranolol and dibenamine caused a marked fall in core temperature (p less than 0.05). These results indicate that beta-catecholamine agonists could play an important role in acute burn mortality and that both alpha- and beta-catecholamine agonists could significantly influence body temperature regulation and metabolic rate during the late postburn period.

Animals↗
PubMed1997

Cyclo (His-Pro) modulation of body temperature at hot ambient temperature in the desert rat (Mastomys natalensis).

Cyclo(His-Pro) (CHP) has been shown to facilitate cold-induced hypothermia in the desert rat Mastomys natalensis. In the present study, we examined the role of endogenous CHP in hyperthermia induced by hot ambient temperature (40 degrees C) in the above rodent species. The results of these studies show that housing rodents at 40 degrees C resulted in a altered distribution of CHP in the brain, with a rise in hypothalamic content accompanied by an increase in rectal temperature. While administration of exogenous CHP decreased hyperthermia, immunoneutralization of endogenous CHP increased hyperthermia. The results of these studies show that changes in endogenous CHP levels may affect body temperature regulation.

Animals↗
PubMed2001

Hypothalamic neuroactivity in specific processes and central regulation of body temperature and water intake.

The method described was designed to elucidate the role of a particular neuronal system or specific nucleus in the central nervous system (CNS) in controlling physiological and biological functions. The neurochemical aspects of the CNS regulatory mechanism and related networks remain to be further investigated. There is little information available about the relationship between neuroactivity in the specific brain nuclei and physiological or biological responses in mammals. An adequate analysis of this relationship provides valuable insight to clarify which nucleus and what types of neurons are truly involved in the excitation of physiological events and its regulation. In the present study, we used microdialysis for stimulation of the anterior hypothalamus (AH) and simultaneous analysis of cholinergic activity, and we investigated c-Fos-like immunoreactivity (Fos-IR) in the brain in the same animal following microdialysis. The nuclear protein c-Fos, the product of c-fos oncogene, has been used as a marker of neuronal activity at the cellular level in the brain. Various physiological and pharmacological stimuli have been shown to induce Fos-IR in specific neuronal populations located in various regions of the brain. However, there are few studies investigating the responses produced by c-Fos expression in specific regions in same animals. We showed the involvement of hypothalamic cholinergic mechanisms in the thermoregulatory and water regulatory processes using the above procedures.

Acetylcholine↗
PubMedDate not supplied

A system with some unique features for maintaining desired body temperature in anesthetized and/or immobilized animals.

We describe the design and unique features of a system for precisely regulating body temperature of anesthetized and/or immobilized small mammals during prolonged neurophysiological experiments. The system uses a flexible, insulated, charcoal cloth conducting blanket which can be intimately wrapped around the animal's body. The temperature of the blanket is continuously regulated by an electronic system which compares the animal's actual temperature with the desired temperature. The system can react to differences of 0.1 to 0.001 degrees C and introduces no recording artifacts. With modification the system may have clinical application.

Anesthesia, General↗
PubMed2002

Presence of alpha-1 adrenoreceptors on thermosensitive neurons in the medial preoptico-anterior hypothalamic area in rats.

Earlier microinjection studies showed that norepinephrine in the medial preoptico-anterior hypothalamic area (mPOAH) regulates body temperature and the action is mediated through alpha-1 adrenoceptors. This study was conducted to confirm if the thermosensitive neurons in the mPOAH of rats possess alpha-1 adrenoceptors. First, the thermosensitivity of mPOAH neurons was tested and then the effects of microiontophoretic application of prazosin, alpha 1 adrenoceptor antagonist, on the firing rate of both the thermosensitive as well as the insensitive neurons were recorded. Prazosin significantly inhibited the firing rate of the thermosensitive neurons suggesting that most of the cold and warm sensitive neurons in the mPOAH possess alpha-1 adrenoceptors. These results at the single neuronal level confirm our earlier hypothesis that in the mPOAH, norepinephrine regulates body temperature by acting on alpha-1 adrenoceptors. The data also suggest that sensitivity of the mPOAH neurons to norepinephrine alter with changes in body temperature. The detailed physiological significance of the results with special reference to thermoregulation at the single neuronal level has been discussed.

Adrenergic alpha-Antagonists↗