scholarly journals Effects of Laboratory Housing Conditions on Core Temperature and Locomotor Activity in Mice

2021 ◽  
Author(s):  
Lauren N Russell ◽  
William S Hyatt ◽  
Brenda M Gannon ◽  
Christy M Simecka ◽  
Mildred M Randolph ◽  
...  
Keyword(s):  
Locomotor Activity ◽  
Ambient Temperature ◽  
Core Temperature ◽  
Wheel Running ◽  
Housing Conditions ◽  
Ambient Temperatures ◽  
Adult Mice ◽  
Circadian Distribution ◽  
Nesting Material ◽  
Nih Swiss

Drug developers worldwide assess compound safety and efficacy using measures that include mouse core temperature andlocomotor activity. Subtle differences in animal housing conditions between institutions can alter these values, impacting scientific rigor and reproducibility. In these studies, adult male NIH Swiss mice were surgically implanted with radiotelemetry probes that simultaneously monitored core temperature and locomotor activity across various housing conditions. In the first study, ambient temperature was varied between 20 °C and 28 °C in groups of singly housed mice. Additional studies held the mice at a constant ambient temperature and examined the effects of cage density (housing animals singly or in groups of 3 or 6), bedding change and provision of nesting material, and the availability of a running wheel on core temperature and locomotor activity. Mice overwhelmingly maintained species-typical core temperatures across all ambient temperatures,across all housing conditions, when bedding was fresh or old, and with or without the provision of cotton squares as nesting material. However, engaging in wheel running and the combination of fresh bedding and cotton squares transiently increased core temperatures beyond the species-typical range. Similarly, the circadian distribution of locomotor activity was significantly disrupted by placing animals in cages with fresh bedding or nesting material, or by performing both of these manipulations concurrently during the light period. These findings suggest that standard husbandry practices and common housing conditions may transiently affect core temperature in adult mice. Furthermore, these practices may have profound and relatively long-lasting effects on motor activity and the regulation of circadian rhythms.

scholarly journals Collective thermoregulation in bee clusters

2014 ◽  
Vol 11 (91) ◽  
pp. 20131033 ◽  
Author(s):  
Samuel A. Ocko ◽  
L. Mahadevan
Keyword(s):  
Ambient Temperature ◽  
Core Temperature ◽  
Continuum Model ◽  
External Temperature ◽  
Ambient Temperatures ◽  
Advection Diffusion ◽  
Central Controller ◽  
Buoyancy Driven Flows ◽  
Dense Cluster

Swarming is an essential part of honeybee behaviour, wherein thousands of bees cling onto each other to form a dense cluster that may be exposed to the environment for several days. This cluster has the ability to maintain its core temperature actively without a central controller. We suggest that the swarm cluster is akin to an active porous structure whose functional requirement is to adjust to outside conditions by varying its porosity to control its core temperature. Using a continuum model that takes the form of a set of advection–diffusion equations for heat transfer in a mobile porous medium, we show that the equalization of an effective ‘behavioural pressure’, which propagates information about the ambient temperature through variations in density, leads to effective thermoregulation. Our model extends and generalizes previous models by focusing the question of mechanism on the form and role of the behavioural pressure, and allows us to explain the vertical asymmetry of the cluster (as a consequence of buoyancy-driven flows), the ability of the cluster to overpack at low ambient temperatures without breaking up at high ambient temperatures, and the relative insensitivity to large variations in the ambient temperature. Our theory also makes testable hypotheses for the response of the cluster to external temperature inhomogeneities and suggests strategies for biomimetic thermoregulation.

Photoperiodic effects on body size and energetics of the collared lemming, Dicrostonyx groenlandicus

1988 ◽  
Vol 66 (4) ◽  
pp. 835-841 ◽  
Author(s):  
P. S. Reynolds ◽  
D. M. Lavigne
Keyword(s):  
Body Size ◽  
Ambient Temperature ◽  
Core Temperature ◽  
Thermal Conductance ◽  
Seasonal Patterns ◽  
Metabolic Rates ◽  
Ambient Temperatures ◽  
Thermoneutral Zone ◽  
Dicrostonyx Groenlandicus ◽  
Phylogenetic Adaptation

Resting metabolic rates of adult collared lemmings, Dicrostonyx groenlandicus, acclimated from weaning to either long, "summer" (22L:2D) or short, "winter" (2L:22D) photoperiod at 15 °C were examined as a function of ambient temperature. Winter morphs were significantly heavier than summer morphs (73.8 ± 7.7 (SD) and 54.5 ± 7.2 (SD) g, respectively). However, there were no differences in mass-specific metabolic rates between treatments at 15 and 20 °C. At low ambient temperatures (0 and −10 °C), metabolic rates of summer morphs were significantly higher than those of winter morphs, indicating a shift in the thermoneutral zone with photoperiod acclimation. There were no significant differences in core temperature between morphs at any ambient temperature. Thermal conductance of winter morphs was significantly lower (0.05 mL O2 (g∙h∙°C)−1) than that of summer morphs (0.09 mL O2 (g∙h∙°C)−1). Comparisons with other myomorph rodents do not support the contention that lemmings have unusually high metabolic rates. However, minimal thermal conductances of lemmings were much lower than expected on the basis of body size. These data suggest that although lemmings may differ in seasonal patterns of energetics from other microtines, there is little evidence to support the assertion that high rates of metabolism are characteristic of all microtines, or that observed basal rates represent a phylogenetic adaptation to cold.

Sleep-waking pattern and body temperature in hypoxia at selected ambient temperatures

1984 ◽  
Vol 57 (5) ◽  
pp. 1564-1568 ◽  
Author(s):  
B. Hale ◽  
D. Megirian ◽  
M. J. Pollard
Keyword(s):  
Body Temperature ◽  
Ambient Temperature ◽  
Core Temperature ◽  
Ambient Temperatures ◽  
State Changes ◽  
Maximum Minimum ◽  
Mild Hypoxia ◽  
Low Ambient Temperature

We studied the effect of mild hypoxia (15% O2) and low ambient temperature (Ta = 15 degrees C) on the rat's sleep-waking pattern (SWP) and maximum-minimum core temperature (max-min Tb). Mild hypoxia at neutral Ta (29 degrees C) disrupted the SWP in the same way as low Ta during normoxia: both affected the pattern of frequency of state changes (P less than 0.01), not the pattern of epoch durations. Mild hypoxia and low Ta together caused a degree of disruption of the SWP which was the sum of each alone, i.e., additive. Although both mild hypoxia and low Ta significantly depressed max-min Tb, low Ta exerted a greater effect than mild hypoxia. Together they further depressed max-min Tb in an additive way. We conclude that mild hypoxia disrupts the rat's SWP independent of central thermoregulatory mechanisms at neutral Ta, that the effects of mild hypoxia and low Ta on the SWP are additive at the stimulus levels used, and that Ta, not inspired O2, determines Tb.

Effects of Ambient Temperature and Forced-air Warming on Intraoperative Core Temperature

2018 ◽  
Vol 128 (5) ◽  
pp. 903-911 ◽  
Author(s):  
Lijian Pei ◽  
Yuguang Huang ◽  
Yiyao Xu ◽  
Yongchang Zheng ◽  
Xinting Sang ◽  
...  
Keyword(s):  
Ambient Temperature ◽  
Temperature Change ◽  
Core Temperature ◽  
Negative Slope ◽  
Anesthesia Induction ◽  
Temperature Changes ◽  
Ambient Temperatures ◽  
Forced Air Warming ◽  
Factorial Trial ◽  
Forced Air

Abstract Background The effect of ambient temperature, with and without active warming, on intraoperative core temperature remains poorly characterized. The authors determined the effect of ambient temperature on core temperature changes with and without forced-air warming. Methods In this unblinded three-by-two factorial trial, 292 adults were randomized to ambient temperatures 19°, 21°, or 23°C, and to passive insulation or forced-air warming. The primary outcome was core temperature change between 1 and 3 h after induction. Linear mixed-effects models assessed the effects of ambient temperature, warming method, and their interaction. Results A 1°C increase in ambient temperature attenuated the negative slope of core temperature change 1 to 3 h after anesthesia induction by 0.03 (98.3% CI, 0.01 to 0.06) °Ccore/(h.°Cambient) (P < 0.001), for patients who received passive insulation, but not for those warmed with forced-air (–0.01 [98.3% CI, –0.03 to 0.01] °Ccore/[h.°Cambient]; P = 0.40). Final core temperature at the end of surgery increased 0.13°C (98.3% CI, 0.07 to 0.20; P < 0.01) per degree increase in ambient temperature with passive insulation, but was unaffected by ambient temperature during forced-air warming (0.02 [98.3% CI, –0.04 to 0.09] °Ccore/°Cambient; P = 0.40). After an average of 3.4 h of surgery, core temperature was 36.3° ± 0.5°C in each of the forced-air groups, and ranged from 35.6° to 36.1°C in passively insulated patients. Conclusions Ambient intraoperative temperature has a negligible effect on core temperature when patients are warmed with forced air. The effect is larger when patients are passively insulated, but the magnitude remains small. Ambient temperature can thus be set to comfortable levels for staff in patients who are actively warmed.

scholarly journals Cognitive Performance During Night Work in the Cold

2021 ◽  
Vol 12 ◽  
Author(s):  
Hilde Færevik ◽  
Jakob Hønborg Hansen ◽  
Øystein Wiggen ◽  
Mariann Sandsund
Keyword(s):  
Reaction Time ◽  
Ambient Temperature ◽  
Cognitive Performance ◽  
Core Temperature ◽  
Short Term Memory ◽  
Night Work ◽  
Short Term ◽  
Term Memory ◽  
Ambient Temperatures ◽  
Cortisol Levels

Objective: The objective of this study was to investigate how night work at low ambient temperatures affects cognitive performance (short-term memory and reaction time), skin- and core temperature, thermal comfort, sleepiness, and cortisol. We hypothesized that cognitive performance is reduced at night compared with daytime and worsened when exposed to low ambient temperatures.Method: Eleven male subjects were recruited to perform three tests in a climatic chamber at night and daytime: Night –2°C, Night 23°C and Day 23°C. Each test lasted 6 h. Cognitive performance (short-term memory and reaction time), skin- and core temperature, thermal sensation and comfort, cortisol levels and sleepiness were measured during the tests.Results: A lower mean skin temperature and corresponding lower thermal sensation were observed at Night –2°C compared to Day 23°C and Night 23°C. Night work caused increased sleepiness and lower cortisol levels, but was not affected by changes in ambient temperatures, thermal comfort, or skin temperatures. There was no effect of either day/night work nor ambient temperature on the short-term memory or reaction time test.Conclusion: Lower skin- and core temperature were observed at night when exposed to low ambient temperature (–2°C), but there was no effect on short-term memory or reaction time. Increased sleepiness and lower cortisol levels were observed at night compared to daytime and was not influenced by low ambient temperature at night. The result from this study suggests that cognitive performance (short-term memory and reaction time) is not adversely affected by night work when exposed to low ambient temperatures if adequate protective clothing is worn.

scholarly journals Behavioral and Thermoregulatory Responses to Changes in Ambient Temperature and Wheel Running Availability in Octodon degus

2021 ◽  
Vol 15 ◽  
Author(s):  
Beatriz Bano-Otalora ◽  
Maria Angeles Rol ◽  
Juan Antonio Madrid
Keyword(s):  
Body Temperature ◽  
Ambient Temperature ◽  
Wheel Running ◽  
Behavioral Activity ◽  
Dark Phase ◽  
Octodon Degus ◽  
Ambient Temperatures ◽  
Temperature Rhythms ◽  
Running Wheels ◽  
The Relationship

Octodon degus is primarily a diurnal species, however, in laboratory conditions, it can switch from diurnal to nocturnal in response to wheel running availability. It has been proposed that this activity inversion obeys thermoregulatory constraints induced by vigorous physical exercise. Thus, its activity shifts to the night as the ambient temperature is lower.Here, we investigate the relationship between thermoregulation and the activity phase-inversion in response to wheel-running in this species. We measured behavioral activity and body temperature rhythms in diurnal naïve animals under 12 h light: 12 h dark cycles at four different ambient temperatures (spanning from ~26°C to 32°C), and following access to running wheels while maintained under high ambient temperature.Our results show that naïve degus do not shift their diurnal activity and body temperature rhythms to a nocturnal phase when subjected to sequential increases in ambient temperature. However, when they were provided with wheels under constant high-temperature conditions, all animals inverted their diurnal phase preference becoming nocturnal. Both, negative masking by light and entrainment to the dark phase appeared involved in the nocturnalism of these animals. Analysis of the thermoregulatory response to wheel running revealed some differences between masked and entrained nocturnal chronotypes.These data highlight the importance of the coupling between wheel running availability and ambient temperature in the nocturnalism of the degus. The results support the view that an innate “protective” pre-program mechanism (associating darkness and lower ambient temperature) may change the timing of behavioral activity in this species to reduce the potential risk of hyperthermia.

The telemetric monitoring of heart rate, locomotor activity, and body temperature in mice and voles (Microtus arvalis) during ambient temperature changes

1996 ◽  
Vol 30 (1) ◽  
pp. 7-12 ◽  
Author(s):  
K. Ishii ◽  
M. Kuwahara ◽  
H. Tsubone ◽  
S. Sugano
Keyword(s):  
Heart Rate ◽  
Locomotor Activity ◽  
Body Temperature ◽  
Ambient Temperature ◽  
Cold Exposure ◽  
Heat Exposure ◽  
Small Rodents ◽  
Temperature Changes ◽  
Ambient Temperatures ◽  
Behavioural Responses

We have studied the physiological and behavioural responses in small rodents to ambient alterations. For this purpose, voles and mice were exposed to relatively low (12°C) and high (35°C) ambient temperatures, and heart rate (HR), locomotor activity (LA) and body temperature (BT) were recorded using telemetry system. The control HR (at 24°C) of voles was lower than that of mice. The 'heat exposure' decreased HR to 85.0±3.3% in voles, and to 78.0±3.2% in mice compared with the mean HR of the same time in the control day. The 'cold exposure' increased the HR to 131.9±8.8% in voles, and 119±10.9% in mice. The decreasing rate of HR in heat exposure was smaller in voles than mice, and in cold exposure the increased rate was larger in voles than mice. Cold exposure decreased BT in both species; 96.1±0.5% in voles and 93.7±1.0% in mice. The LA was not changed significantly by heat exposure in either species, but was partially increased by cold exposure. These results demonstrate that telemetry was helpful for qualitative and quantitative behavioural studies in small rodents, and confirmed that the physiological and behavioural responses to ambient temperature changes differed between these animals.

scholarly journals Activation of Neurokinin 3 Receptors in the Median Preoptic Nucleus Decreases Core Temperature in the Rat

Endocrinology ◽  
2011 ◽  
Vol 152 (12) ◽  
pp. 4894-4905 ◽  
Author(s):  
Penny A. Dacks ◽  
Sally J. Krajewski ◽  
Naomi E. Rance
Keyword(s):  
Body Temperature ◽  
Ambient Temperature ◽  
Core Temperature ◽  
Ovariectomized Rats ◽  
Dependent Manner ◽  
Preoptic Nucleus ◽  
Ambient Temperatures ◽  
Median Preoptic Nucleus ◽  
Estrogen Withdrawal ◽  
Neurokinin 3 Receptor

Estrogens have pronounced effects on thermoregulation, as illustrated by the occurrence of hot flushes secondary to estrogen withdrawal in menopausal women. Because neurokinin B (NKB) gene expression is markedly increased in the infundibular (arcuate) nucleus of postmenopausal women, and is modulated by estrogen withdrawal and replacement in multiple species, we have hypothesized that NKB neurons could play a role in the generation of flushes. There is no information, however, on whether the primary NKB receptor [neurokinin 3 receptor (NK3R)] modulates body temperature in any species. Here, we determine the effects of microinfusion of a selective NK3R agonist (senktide) into the rat median preoptic nucleus (MnPO), an important site in the heat-defense pathway. Senktide microinfusion into the rat MnPO decreased core temperature in a dose-dependent manner. The hypothermia induced by senktide was similar in ovariectomized rats with and without 17β-estradiol replacement. The hypothermic effect of senktide was prolonged in rats exposed to an ambient temperature of 29.0 C, compared with 21.5 C. Senktide microinfusion also altered tail skin vasomotion in rats exposed to an ambient temperature of 29.0 but not 21.5 C. Comparisons of the effects of senktide at different ambient temperatures indicated that the hypothermia was not secondary to thermoregulatory failure or a reduction in cold-induced thermogenesis. Other than a very mild increase in drinking, senktide microinfusion did not affect behavior. Terminal fluorescent dextran microinfusion showed targeting of the MnPO and adjacent septum, and immunohistochemical studies revealed that senktide induced a marked increase in Fos-activation in the MnPO. Because MnPO neurons expressed NK3R-immunoreactivity, the induction of MnPO Fos by senktide is likely a direct effect. By demonstrating that NK3R activation in the MnPO modulates body temperature, these studies support the hypothesis that hypothalamic NKB neurons could be involved in the generation of menopausal flushes.

scholarly journals Influence of Ambient Temperature on Radiative and Convective Heat Dissipation Ratio in Polymer Heat Sinks

Polymers ◽  
2021 ◽  
Vol 13 (14) ◽  
pp. 2286
Author(s):  
Jan Kominek ◽  
Martin Zachar ◽  
Michal Guzej ◽  
Erik Bartuli ◽  
Petr Kotrbacek
Keyword(s):  
Heat Transfer ◽  
Ambient Temperature ◽  
Convective Heat ◽  
Heat Dissipation ◽  
High Surface ◽  
Heat Sinks ◽  
Fourth Power ◽  
Molding Process ◽  
Ambient Temperatures ◽  
University Of Technology

Miniaturization of electronic devices leads to new heat dissipation challenges and traditional cooling methods need to be replaced by new better ones. Polymer heat sinks may, thanks to their unique properties, replace standardly used heat sink materials in certain applications, especially in applications with high ambient temperature. Polymers natively dispose of high surface emissivity in comparison with glossy metals. This high emissivity allows a larger amount of heat to be dissipated to the ambient with the fourth power of its absolute surface temperature. This paper shows the change in radiative and convective heat transfer from polymer heat sinks used in different ambient temperatures. Furthermore, the observed polymer heat sinks have differently oriented graphite filler caused by their molding process differences, therefore their thermal conductivity anisotropies and overall cooling efficiencies also differ. Furthermore, it is also shown that a high radiative heat transfer leads to minimizing these cooling efficiency differences between these polymer heat sinks of the same geometry. The measurements were conducted at HEATLAB, Brno University of Technology.

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