Indomethacin impairs LPS-induced behavioral fever in toads

2002 ◽  
Vol 93 (2) ◽  
pp. 512-516 ◽  
Author(s):  
K. C. Bicego ◽  
A. A. Steiner ◽  
J. Antunes-Rodrigues ◽  
L. G. S. Branco
Keyword(s):  
Body Temperature ◽  
Thermal Gradient ◽  
Behavioral Thermoregulation ◽  
Cyclooxygenase Inhibitor ◽  
Set Point ◽  
Behavioral Fever ◽  
Preferred Body Temperature ◽  
Baseline Values ◽  
Toad Bufo

We tested the hypothesis that PGs mediate lipopolysaccharide (LPS)-induced behavioral fever in the toad Bufo paracnemis. Measurements of preferred body temperature (Tb) were performed with a thermal gradient. Toads were injected intraperitoneally with the cyclooxygenase inhibitor indomethacin (5 mg/kg), which inhibits PG biosynthesis, or its vehicle (Tris) followed 30 min later by LPS (0.2 and 2 mg/kg) into the lymph sac. LPS at the dose of 0.2 mg/kg caused a significant increase in Tb from 7 to 10 h after injection, and then Tb returned toward baseline values. LPS at the dose of 2 mg/kg produced a different pattern of response, with a longer latency to the onset of fever (10th h) and a longer duration (until the end of the experiment at the 15th h). Tris significantly attenuated the fever induced by LPS at 0.2 mg/kg, but not at 2 mg/kg. Moreover, indomethacin completely blocked the fever evoked by LPS (2 mg/kg). These results indicate that the behavioral fever induced by LPS in toads requires the activation of the COX pathway, suggesting that the involvement of PG in fever has an ancient phylogenetic history and that endogenous PGs raise the thermoregulatory set point to produce fever, because behavioral thermoregulation seems to be related to changes in the thermoregulatory set point.

Antipyretic effect of arginine vasotocin in toads

2000 ◽  
Vol 278 (6) ◽  
pp. R1408-R1414 ◽  
Author(s):  
K. C. Bicego-Nahas ◽  
A. A. Steiner ◽  
E. C. Carnio ◽  
J. Antunes-Rodrigues ◽  
L. G. S. Branco
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Body Temperature ◽  
Thermal Gradient ◽  
Arginine Vasotocin ◽  
Antipyretic Effect ◽  
The Central Nervous System ◽  
Preferred Body Temperature ◽  
Toad Bufo

Arginine vasotocin (AVT) is a nonmammalian analog of the mammalian hormone arginine vasopressin (AVP). These peptides are known for their antidiuretic and pressor effects. More recently, AVP has been recognized as an important antipyretic molecule in mammals. However, no information exists about the role of AVT in febrile ectotherms. We tested the hypothesis that AVT is an antipyretic molecule in the toad Bufo paracnemis. Toads equipped with a temperature probe were placed in a thermal gradient, and preferred body temperature was recorded continuously. A behavioral fever was observed after lipopolysaccharide (LPS) was injected systemically (200 μg/kg). Systemically injected AVT (300 pmol/kg) alone caused no significant change in body temperature, but abolished LPS-induced fever. Moreover, a smaller dose of AVT (10 pmol/kg), which did not affect LPS-induced fever when injected peripherally, abolished fever when injected intracerebroventricularly. We therefore conclude that AVT plays an antipyretic role in the central nervous system, by means of behavior, in an ectotherm, a fact consistent with the notion that AVT/AVP elicits antipyresis by reducing the thermoregulatory set point.

scholarly journals Behavioral thermoregulation in obese and lean Zucker rats in a thermal gradient

2001 ◽  
Vol 281 (5) ◽  
pp. R1675-R1680 ◽  
Author(s):  
Michael Maskrey ◽  
Paul R. Wiggins ◽  
Peter B. Frappell
Keyword(s):  
Thermal Gradient ◽  
Activity Cycle ◽  
Body Core Temperature ◽  
Zucker Rats ◽  
Behavioral Thermoregulation ◽  
Dark Cycle ◽  
Set Point ◽  
Open Flow ◽  
Radio Transmitter ◽  
Body Core

Genetically obese Zucker (Z) rats have been reported to display a body core temperature (Tb) that is consistently below that of their lean littermates. We asked the question whether the lower Tb was a result of deficits in thermoregulation or a downward resetting of the set point for Tb. For a period of 45 consecutive hours, lean and obese Z rats were free to move within a thermal gradient with an ambient temperature (Ta) range of 15–35°C, while subjected to a 12:12-h light-dark cycle. Tb was measured using a miniature radio transmitter implanted within the peritoneal cavity. Oxygen consumption (V˙o 2) was measured using an open flow technique. Movements and most frequently occupied position in the gradient (preferred Ta) were recorded using a series of infrared phototransmitters. Obese Z rats were compared with lean Z rats matched for either age (A) or body mass (M). Our results show that obese Z rats have a lower Tb[37.1 ± 0.1°C (SD) vs. 37.3 ± 0.1°C, P< 0.001] and a lower V˙o 2 (25.3 ± 1.9 ml · kg−1 · h−1) than lean controls [33.1 ± 3.7 (A) and 33.9 ± 3.9 (M) ml · kg−1 · h−1, P < 0.001]. Also, the obese Z rats consistently chose to occupy a cooler Ta [20.9 ± 0.6°C vs. 22.7 ± 0.6°C (A) and 22.5 ± 0.7°C (M), P < 0.001] in the thermal gradient. This suggests a lower set point for Tb in the obese Z rat, as they refused the option to select a warmer Ta that might allow them to counteract any thermoregulatory deficiency that could lead to a low Tb. Although all rats followed a definite circadian rhythm for both Tb and V˙o 2, there was no discernible circadian pattern for preferred Ta in either obese or lean rats. Obese Z rats tended to show a far less definite light-dark activity cycle compared with lean rats.

Pyrogens fail to produce fever in a cordylid lizard

1981 ◽  
Vol 241 (3) ◽  
pp. R198-R202 ◽  
Author(s):  
H. P. Laburn ◽  
D. Mitchell ◽  
E. Kenedi ◽  
G. N. Louw
Keyword(s):  
Body Temperature ◽  
Ambient Temperature ◽  
Aeromonas Hydrophila ◽  
Thermal Gradient ◽  
Negative Bacterium ◽  
Gram Negative ◽  
Sterile Saline ◽  
Rabbit Blood ◽  
Preferred Body Temperature

We investigated the effects on body temperature of the lizard Cordylus cataphractus of intracardiac injections of leucocyte pyrogen (LP) synthesized from rabbit blood and of killed Aeromonas hydrophila, a gram-negative bacterium reputed to be pathogenic in lizards. Lizards were placed in a photothermal gradient that allowed them to select a preferred body temperature following the injections. Neither injection of 0.5 ml rabbit LP nor of 4 X 10(9) organisms of A. hydrophila in 0.2 ml sterile saline caused body temperature of lizards to differ from that of control lizards injected with sterile saline. Following injection of these solutions in the lizards placed in a thermal gradient where ambient temperature ranged from 20-88 degrees C, body temperature was maintained between 32 and 34 degrees C. Pyrogens failed to elevate body temperature even when body temperature was elevated artificially to 36 degrees C before injection. We conclude that C. cataphractus does not respond with fever to either rabbit LP or A. hydrophila. Fever may not be ubiquitous even among lizards.

scholarly journals Fever and behavioral thermoregulation in young and old rats

2001 ◽  
Vol 280 (5) ◽  
pp. R1457-R1461 ◽  
Author(s):  
Maria Florez-Duquet ◽  
Elizabeth Peloso ◽  
Evelyn Satinoff
Keyword(s):  
Thermal Gradient ◽  
Behavioral Thermoregulation ◽  
Standard Laboratory ◽  
Set Point ◽  
Ambient Temperatures ◽  
The Third ◽  
Young Rats ◽  
Old Rats

At standard laboratory ambient temperatures (Ta) of 20–24°C, peripheral injections of lipopolysaccharide (LPS) reliably produce fever in young rats. In contrast, old rats may show a blunted fever, no fever, or even hypothermia after LPS. In the present study we hypothesized that old rats might use behavioral thermoregulation to help them develop a fever. Young and old rats were implanted with temperature transmitters. At least 1 wk postoperatively they were placed in a thermally graded alleyway (Ta10–40°C). On the third and sixth day they were taken out of the gradient, placed at an Taof 23°C, injected intraperitoneally with LPS or saline, and left at 23°C for 3 h. At the end of that time, all young rats had become febrile, whereas the old rats had not. When the rats were replaced in the thermal gradient, the young animals continued to develop a fever that was similar to fever in young rats left at 23°C. The old animals chose significantly warmer positions in the thermal gradient than did the young animals and only then became febrile. Although there was a tendency for the young rats to prefer higher Taafter LPS than after saline, these differences were not significant. However, the differences in the old rats were significant. These results suggest that the LPS had increased the thermal set point in the old rats, but they could develop febrile responses only at the warm Tathey selected.

Melatonin and thermoregulation in ectothermic vertebrates: a review

2003 ◽  
Vol 81 (1) ◽  
pp. 1-13 ◽  
Author(s):  
Deborah I Lutterschmidt ◽  
William I Lutterschmidt ◽  
Victor H Hutchison
Keyword(s):  
Body Temperature ◽  
Pineal Gland ◽  
Behavioral Thermoregulation ◽  
Review Of The Literature ◽  
Thermoregulatory Behavior ◽  
Pineal Complex ◽  
Set Point ◽  
Environmental Stimuli ◽  
Interspecific Differences

Precise behavioral thermoregulation is well documented in many ectothermic vertebrates. However, many complexities involving the influence of the pineal gland and melatonin (MEL) on thermoregulatory behavior, and thus body temperature (Tb), remain unresolved. Although MEL is commonly considered to decrease Tb in both endotherms and ectotherms, several ectothermic species do not modulate Tb in response to MEL. Furthermore, it is not yet clear how MEL integrates thermoregulatory behavior with environmental stimuli or how it modulates Tb. Some inferences about MEL action in endotherms are not applicable to ectotherms. Changes in ectothermic Tb are mediated primarily through behavioral modulation (not physiological modulation as in endotherms). Thus, the most likely mechanism underlying MEL's actions on ectothermic Tb is adjustment of the temperature set point in the hypothalamus. We provide a review of the literature addressing the effects of MEL on thermoregulatory behavior in ectothermic vertebrates. We also discuss mechanisms underlying MEL's influence on physiological and behavioral processes in ectotherms and hypotheses regarding interspecific differences in pineal complex and MEL function.

Effect of hematocrit on behavioral thermoregulation of the toad Bufo marinus

1990 ◽  
Vol 258 (4) ◽  
pp. R848-R851 ◽  
Author(s):  
S. C. Wood
Keyword(s):  
Thermal Gradient ◽  
Bufo Marinus ◽  
The Body ◽  
Behavioral Thermoregulation ◽  
Blood Doping ◽  
Cross Sectional ◽  
Oxygen Capacity ◽  
The Mean ◽  
Sectional Analysis ◽  
Toad Bufo

This study tested the hypothesis that the oxygen capacity of blood, indexed by hematocrit, affects the body temperature (Tb) selected by toads (Bufo marinus) in a thermal gradient. Anesthetized toads (Brevital sodium; 40 mg/kg im) were fitted with a cloacal thermistor and femoral artery cannula. After recovery, they were placed in a thermal gradient ranging from approximately 10 to 40 degrees C. Tb was measured for 24 h. Then 1-2 ml blood were withdrawn and replaced with an equal volume of either 0.66% saline or packed red cells from donor toads. Selected Tb was measured for the next 24 h. The mean Tb selected by B. marinus (n = 33) was 24.9 degrees C. Cross-sectional analysis showed no correlation between selected Tb and hematocrit. However, each toad rendered anemic showed a reduction of selected Tb (mean = 22.9 degrees C). The degree of Tb reduction was correlated with the hematocrit reduction, (r = 0.86; P = 0.013). Blood doping did not have a significant effect on selected Tb. The reduction of Tb could be adaptive by reducing oxygen consumption.

24-hour control of body temperature in rats. I. Integration of behavioral and autonomic effectors

1994 ◽  
Vol 267 (1) ◽  
pp. R71-R77 ◽  
Author(s):  
C. J. Gordon
Keyword(s):  
Heart Rate ◽  
Body Temperature ◽  
Behavioral Thermoregulation ◽  
Gradient System ◽  
Dark Phase ◽  
Light Phase ◽  
Set Point ◽  
Selection Of ◽  
Dark Transition

Some studies suggest that the nocturnal elevation in core temperature (Tc) of the rat is mediated by an elevation in the set point. The role of set point can be assessed if behavioral effectors are measured simultaneously with other thermoregulatory effectors and Tc over a 24-h period. Selected ambient temperature (STa) and motor activity (MA) were measured in rats housed in a temperature gradient system with a 12:12-h photoperiod (lights on 0600 h). Tc and heart rate (HR) were monitored by telemetry. During the light phase, STa, Tc, HR, and MA were relatively stable with values 29.0 degrees C, 37.1 degrees C, 310 beats/min, and 1-2 m/h, respectively. During the light-to-dark transition there were abrupt elevations in Tc, HR, and MA but no change in STa. STa decreased during the dark phase and reached a nadir of 23 degrees C at 0500 h. All variables recovered to basal levels within 3-4 h after the onset of the light phase. Overall, autonomic effectors control the elevation in Tc during the onset of the dark phase while behavioral effectors have little if any role. Behavioral thermoregulation is important in two ways: 1) the selection of cooler Ta values at night to prevent an excess elevation in Tc and 2) a preference for cooler Ta values before the light phase to facilitate the recovery of Tc.

Comparative effects of hypoxia on behavioral thermoregulation in rats, hamsters, and mice

1991 ◽  
Vol 260 (1) ◽  
pp. R120-R125 ◽  
Author(s):  
C. J. Gordon ◽  
L. Fogelson
Keyword(s):  
Statistical Analysis ◽  
Body Temperature ◽  
Temperature Gradient ◽  
Sample Size ◽  
Oxygen Content ◽  
Rodent Species ◽  
Behavioral Thermoregulation ◽  
Body Temperatures ◽  
Set Point ◽  
Deep Body

Recent studies using reptiles and other ectothermic species have shown that hypoxia lowers the set point for the control of body temperature. This is characterized by a preference for cooler ambient (Ta) and deep body temperatures (Tb) when placed in a temperature gradient. To elucidate the presence of this effect in mammals, the selected Ta and Tb of three rodent species (mouse, hamster, and rat) were measured while subjected to graded hypoxia in a temperature gradient. Individual animals were placed in the gradient for 30 min. Oxygen content of air entering the gradient was then reduced to a constant level for a period of 60 min by dilution with nitrogen. Tb was significantly reduced in all species at %O2 levels of 5.5-10%. Selected Ta was significantly reduced in the mouse at %O2 levels of 5.5 and 7.3%. Selected Ta of the hamster and rat were reduced slightly at %O2 levels of 5.8 and 7.4%, respectively; however, the effect was not statistically significant. To clarify the effects of hypoxia in these two species, the sample size of rat and hamster was increased to strengthen statistical analysis, and the animals were exposed for 60 min to %O2 levels of 7.4 and 6.7%, respectively. Both species exhibited a significant reduction in selected Ta during hypoxia concomitant with hypothermia. These data support the hypothesis that hypoxia lowers the set point for the control of body temperature in rodents.

Discrete electrolytic lesion of the preoptic area prevents LPS-induced behavioral fever in toads

2002 ◽  
Vol 205 (22) ◽  
pp. 3513-3518
Author(s):  
Kenia C. Bicego ◽  
Luiz G. S. Branco
Keyword(s):  
Thermal Gradient ◽  
Preoptic Area ◽  
Electrolytic Lesion ◽  
Behavioral Fever ◽  
Electrolytic Lesions ◽  
The Central Nervous System ◽  
Toad Bufo ◽  
Important Site ◽  
Control Sham

SUMMARY The preoptic area (POA) plays an important role in fever in mammals, but the role of this region in fever in ectothermic vertebrates has never been assessed. Toads, like all ectotherms, regulate their body temperature(Tb) primarily by behavior and develop behavioral fever when injected with lipopolysaccharide (LPS). Therefore, we tested the hypothesis that the POA plays a role in the behavioral fever induced by LPS in the toad Bufo paracnemis. We made electrolytic lesions in the POA of toads (0.3 mA, 8 s) and measured preferred Tb using a thermal gradient. After a period of 24h inside the gradient chamber, control,sham-operated and lesioned toads were systemically injected with LPS (200μg kg-1) or pyrogen-free saline. There was no significant effect of POA lesion in animals at their normal preferred Tb. LPS caused a significant increase in preferred Tb of control and sham-operated toads, but lesions in the POA abolished this response. These results indicate that the POA is an important site in the central nervous system of toads, and perhaps of all vertebrates, involved in the development of fever.

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