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Scariot PPM, Papoti M, Polisel EEC, Orsi JB, Van Ginkel PR, Prolla TA, Manchado-Gobatto FB, Gobatto CA. Living high - training low model applied to C57BL/6J mice: Effects on physiological parameters related to aerobic fitness and acid-base balance. Life Sci 2023; 317:121443. [PMID: 36709910 DOI: 10.1016/j.lfs.2023.121443] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2022] [Revised: 01/17/2023] [Accepted: 01/23/2023] [Indexed: 01/27/2023]
Abstract
There is a scarcity of data regarding the acclimation to high altitude (hypoxic environment) accompanied by training at low altitude (normoxic conditions), the so-called "living high-training low" (LHTL) model in rodents. We aimed to investigate the effects of aerobic training on C57BL/6J mice living in normoxic (NOR) or hypoxic (HYP) environments on several parameters, including critical velocity (CV), a parameter regarded as a measure of aerobic capacity, on monocarboxylate transporters (MCTs) in muscles and hypothalamus, as well as on hematological parameters and body temperature. In each environment, mice were divided into non-trained (N) and trained (T). Forty rodents were distributed into the following experimental groups (N-NOR; T-NOR; N-HYP and T-HYP). HYP groups were in a normobaric tent where oxygen-depleted air was pumped from a hypoxia generator set an inspired oxygen fraction [FiO2] of 14.5 %. The HYP-groups were kept (18 h per day) in a normobaric tent for consecutive 8-weeks. Training sessions were conducted in normoxic conditions ([FiO2] = 19.5 %), 5 times per week (40 min per session) at intensity equivalent to 80 % of CV. In summary, eight weeks of LHTL did not promote a greater improvement in the CV, protein expression of MCTs in different tissues when compared to the application of training alone. The LHTL model increased red blood cells count, but reduced hemoglobin per erythrocyte was found in mice exposed to LHTL. Although the LHTL did not have a major effect on thermographic records, exercise-induced hyperthermia (in the head) was attenuated in HYP groups when compared to NOR groups.
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Affiliation(s)
- Pedro Paulo Menezes Scariot
- Laboratory of Applied Sport Physiology, School of Applied Sciences, University of Campinas, Limeira, SP, Brazil
| | - Marcelo Papoti
- School of Physical Education and Sport of Ribeirão Preto, University of São Paulo, SP, Brazil
| | | | - Juan Bordon Orsi
- Laboratory of Applied Sport Physiology, School of Applied Sciences, University of Campinas, Limeira, SP, Brazil
| | - Paul R Van Ginkel
- Department of Genetics & Medical Genetics, University of Wisconsin, Madison, WI, USA
| | - Tomas A Prolla
- Department of Genetics & Medical Genetics, University of Wisconsin, Madison, WI, USA
| | | | - Claudio Alexandre Gobatto
- Laboratory of Applied Sport Physiology, School of Applied Sciences, University of Campinas, Limeira, SP, Brazil.
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Madelaire CB, Klink AC, Israelsen WJ, Hindle AG. Fibroblasts as an experimental model system for the study of comparative physiology. Comp Biochem Physiol B Biochem Mol Biol 2022; 260:110735. [PMID: 35321853 DOI: 10.1016/j.cbpb.2022.110735] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2021] [Revised: 03/15/2022] [Accepted: 03/17/2022] [Indexed: 10/18/2022]
Abstract
Mechanistic evaluations of processes that underlie organism-level physiology often require reductionist approaches. Dermal fibroblasts offer one such approach. These cells are easily obtained from minimally invasive skin biopsy, making them appropriate for the study of protected and/or logistically challenging species. Cell culture approaches permit extensive and fine-scale sampling regimes as well as gene manipulation techniques that are not feasible in vivo. Fibroblast isolation and culture protocols are outlined here for primary cells, and the benefits and drawbacks of immortalization are discussed. We show examples of physiological metrics that can be used to characterize primary cells (oxygen consumption, translation, proliferation) and readouts that can be informative in understanding cell-level responses to environmental stress (lactate production, heat shock protein induction). Importantly, fibroblasts may display fidelity to whole animal physiological phenotypes, facilitating their study. Fibroblasts from Antarctic Weddell seals show greater resilience to low temperatures and hypoxia exposure than fibroblasts from humans or rats. Fibroblast oxygen consumption rates are not affected by temperature stress in the heat-tolerant camel, whereas similar temperature exposures depress mitochondrial metabolism in fibroblasts from rhinoceros. Finally, dermal fibroblasts from a hibernator, the meadow jumping mouse, better resist experimental cooling than a fibroblast line from the laboratory mouse, with the hibernator demonstrating a greater maintenance of homeostatic processes such as protein translation. These results exemplify the parallels that can be drawn between fibroblast physiology and expectations in vivo, and provide evidence for the power of fibroblasts as a model system to understand comparative physiology and biomedicine.
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Affiliation(s)
- Carla B Madelaire
- School of Life Sciences, University of Nevada Las Vegas, Las Vegas, NV, USA
| | - Amy C Klink
- School of Life Sciences, University of Nevada Las Vegas, Las Vegas, NV, USA
| | - William J Israelsen
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX, USA; Skroot Laboratory, Inc., Ames, IA, USA
| | - Allyson G Hindle
- School of Life Sciences, University of Nevada Las Vegas, Las Vegas, NV, USA.
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3
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Yao Z, Huang K, Qi Y. Post-exercise Hypothermia Varies Between High- and Low-Altitude Populations in the Asiatic Toad (Bufo gargarizans). Front Ecol Evol 2022. [DOI: 10.3389/fevo.2022.846663] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Whether and how poikilothermic animals change their thermal performance to cope with global warming are crucial questions to predict the future of biodiversity. Intraspecific comparison among populations that occur in different climatic zones can provide insight into how poikilotherms may alter their thermal performance under a particular climatic event. We compared populations of the Asiatic toad (Bufo gargarizans) from two altitudinal zones (3239 and 926 m above sea level) to explore variations of post-exercise hypothermia, which can lead to lower temperature preference than normal conditions. Common garden experiment was also employed to test plasticity of hypothermic performance in adult toads. As results, exhaustive exercise induced measurable reduction in body temperature for both populations. Furthermore, high-altitude population experienced larger reduction in body temperature than low-altitude conspecifics in both original habitat and common garden conditions. Therefore, low-altitude toads may to enhance their hypothermic reaction if they shift their ranges to higher altitudes to survive warming climate; However, the relatively limited plasticity of hypothermic performance may constraint their adaptative process.
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Correlation between convection requirement and carotid body responses to hypoxia and hemoglobin affinity: comparison between two rat strains. J Comp Physiol B 2021; 191:1031-1045. [PMID: 33970341 DOI: 10.1007/s00360-021-01377-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2020] [Revised: 03/31/2021] [Accepted: 04/13/2021] [Indexed: 02/06/2023]
Abstract
We tested the hypothesis that differences in ventilatory ([Formula: see text]) or convection requirement ([Formula: see text]/[Formula: see text]O2) response to hypoxia would be correlated with differences in hemoglobin (Hb) oxygen affinity between two strains of rats, as they have been shown to be among several species of mammals, birds and reptiles. Brown Norway (BN) rats reduce metabolism more than they increase ventilation in response to hypoxia and both the ventilatory and convection requirement responses to hypoxia are lower in the BN than the Sprague-Dawley (SD) rat. The lower threshold of the ventilation/convection requirement responses of the BN to hypoxia are associated with a higher affinity Hb than the SD rats, (P50 values of 32.4 (± 0.6) versus 34.4 (± 0.5), respectively (P < 0.05), and P75 values of 46.1 (± 0.5) for BN versus 50.7 (± 0.8) for SD (P < 0.001). This significant difference, particularly near the inflection point of the dissociation curve, supported our hypothesis. A reduced sensitivity of BN compared to SD carotid bodies was found. BN carotid bodies (from 36 20-60-day-olds) had a mean estimated volume of 26.64 ± 1.47 × 106 μm3, significantly (P < 0.0001) smaller than SD carotid bodies (from 46 16-40-day-olds) at 50.66 ± 3.41 × 106 μm3. Both genetic and epigenetic/developmental mechanisms may account for the observed inter-strain differences.
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Claunch NM, Nix E, Royal AE, Burgos LP, Corn M, DuBois PM, Ivey KN, King EC, Rucker KA, Shea TK, Stepanek J, Vansdadia S, Taylor EN. Body size impacts critical thermal maximum measurements in lizards. JOURNAL OF EXPERIMENTAL ZOOLOGY PART 2020; 335:96-107. [PMID: 32851814 DOI: 10.1002/jez.2410] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Revised: 08/10/2020] [Accepted: 08/13/2020] [Indexed: 12/18/2022]
Abstract
Understanding the mechanisms behind critical thermal maxima (CTmax; the high body temperature at which neuromuscular coordination is lost) of organisms is central to understanding ectotherm thermal tolerance. Body size is an often overlooked variable that may affect interpretation of CTmax, and consequently, how CTmax is used to evaluate mechanistic hypotheses of thermal tolerance. We tested the hypothesis that body size affects CTmax and its interpretation in two experimental contexts. First, in four Sceloporus species, we examined how inter- and intraspecific variation in body size affected CTmax at normoxic and experimentally induced hypoxic conditions, and cloacal heating rate under normoxic conditions. Negative relationships between body size and CTmax were exaggerated in larger species, and hypoxia-related reductions in CTmax were unaffected by body size. Smaller individuals had faster cloacal heating rates and higher CTmax, and variation in cloacal heating rate affected CTmax in the largest species. Second, we examined how body size interacted with the location of body temperature measurements (i.e., cloaca vs. brain) in Sceloporus occidentalis, then compared this in living and deceased lizards. Brain temperatures were consistently lower than cloacal temperatures. Smaller lizards had larger brain-cloacal temperature differences than larger lizards, due to a slower cloacal heating rate in large lizards. Both live and dead lizards had lower brain than cloacal temperatures, suggesting living lizards do not actively maintain lower brain temperatures when they cannot pant. Thermal inertia influences CTmax data in complex ways, and body size should therefore be considered in studies involving CTmax data on species with variable sizes.
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Affiliation(s)
- Natalie M Claunch
- Biological Sciences, California Polytechnic State University, San Luis Obispo, California
| | - Emmeleia Nix
- Biological Sciences, California Polytechnic State University, San Luis Obispo, California
| | - Averil E Royal
- Biological Sciences, California Polytechnic State University, San Luis Obispo, California
| | - Luis P Burgos
- Biological Sciences, California Polytechnic State University, San Luis Obispo, California
| | - Megan Corn
- Biological Sciences, California Polytechnic State University, San Luis Obispo, California
| | - P Mason DuBois
- Biological Sciences, California Polytechnic State University, San Luis Obispo, California
| | - Kathleen N Ivey
- Biological Sciences, California Polytechnic State University, San Luis Obispo, California
| | - Elina C King
- Biological Sciences, California Polytechnic State University, San Luis Obispo, California
| | - Kiley A Rucker
- Biological Sciences, California Polytechnic State University, San Luis Obispo, California
| | - Tanner K Shea
- Biological Sciences, California Polytechnic State University, San Luis Obispo, California
| | - John Stepanek
- Biological Sciences, California Polytechnic State University, San Luis Obispo, California
| | - Sunny Vansdadia
- Biological Sciences, California Polytechnic State University, San Luis Obispo, California
| | - Emily N Taylor
- Biological Sciences, California Polytechnic State University, San Luis Obispo, California
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Dzal YA, Milsom WK. Hypoxia alters the thermogenic response to cold in adult homeothermic and heterothermic rodents. J Physiol 2019; 597:4809-4829. [PMID: 31365126 DOI: 10.1113/jp277183] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2018] [Accepted: 07/26/2019] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS For small mammals living in a cold, hypoxic environment, supplying enough O2 to sustain thermogenesis can be challenging. While heterothermic mammals are generally more tolerant of cold and hypoxia than homeothermic mammals, how they regulate O2 supply and demand during progressive cooling in hypoxia is largely unknown. We show that as ambient temperature is reduced in hypoxia, body temperature falls in both homeotherms and heterotherms. In the homeothermic rat, a decrease in O2 consumption rate and lung O2 extraction accompany this fall in body temperature, despite a relative hyperventilation. Paradoxically, in heterothermic mice, hamsters and ground squirrels, body temperature decreases more than in the homeothermic rat, even though they maintain ventilation, increase lung O2 extraction and maintain or elevate their O2 consumption rates. Variation in cold and hypoxia tolerance among homeotherms and heterotherms reflects divergent strategies in how O2 supply and demand are regulated under thermal and hypoxic challenges. ABSTRACT Compared to homeothermic mammals, heterothermic mammals are reported to be exceptionally tolerant of cold and hypoxia. We hypothesised that this variation in tolerance stems from divergent strategies in how homeotherms and heterotherms regulate O2 supply versus O2 demand when exposed to hypoxia during progressive cooling. To test this hypothesis, we exposed adult rodents ranging in their degree of heterothermic expression (homeotherm: rats, facultative heterotherms: mice and hamsters, and obligate heterotherm: ground squirrels) to either normoxia (21% O2 ) or environmental hypoxia (7% O2 ), while reducing ambient temperature from 38 to 5°C. We found that when ambient temperature was reduced in normoxia, all species increased their O2 consumption rate and ventilation in parallel, maintaining a constant ventilatory equivalent and level of lung O2 extraction. Surprisingly, body temperature fell in all species, significantly so in the heterotherms. When ambient temperature was reduced in hypoxia, however, the homeothermic rat decreased their O2 consumption rate and lung O2 extraction despite an increase in their ventilatory equivalent, indicative of a relative hyperventilation. Heterotherms (mice, hamsters and ground squirrels), on the other hand, decreased their ventilatory equivalent, but increased lung O2 extraction and maintained or elevated their O2 consumption rates, yet their body temperature fell even more than in the rat. These results are consistent with the idea that homeotherms and heterotherms diverge in the strategies they use to match O2 supply and O2 demand, and that enhanced cold and hypoxia tolerance in heterotherms may stem from an improved ability to extract O2 from the inspired air.
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Affiliation(s)
- Yvonne A Dzal
- Department of Biology and Centre for Forest Interdisciplinary Research, University of Winnipeg, Winnipeg, Manitoba, Canada
| | - William K Milsom
- Department of Zoology, University of British Columbia, Vancouver, British Columbia, Canada
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Landry JP, Hawkins C, Lee A, Coté A, Balaban E, Pompeiano M. Chick embryos have the same pattern of hypoxic lower-brain activation as fetal mammals. Dev Neurobiol 2015; 76:64-74. [DOI: 10.1002/dneu.22299] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2014] [Revised: 04/01/2015] [Accepted: 05/06/2015] [Indexed: 11/06/2022]
Affiliation(s)
- Jeremy P. Landry
- Department of Psychology; McGill University; Montreal Quebec Canada H3A 1B1
| | - Connor Hawkins
- Department of Psychology; McGill University; Montreal Quebec Canada H3A 1B1
| | - Aaron Lee
- Department of Psychology; McGill University; Montreal Quebec Canada H3A 1B1
| | - Alexandra Coté
- Department of Psychology; McGill University; Montreal Quebec Canada H3A 1B1
| | - Evan Balaban
- Department of Psychology; McGill University; Montreal Quebec Canada H3A 1B1
| | - Maria Pompeiano
- Department of Psychology; McGill University; Montreal Quebec Canada H3A 1B1
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8
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Wrotek S, Rosochowicz T, Nowakowska A, Kozak W. Thermal and motor behavior in experimental autoimmune encephalitis in Lewis rats. Autoimmunity 2014; 47:334-40. [PMID: 24625014 DOI: 10.3109/08916934.2014.897332] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Thermoregulation in patients, who suffer from multiple sclerosis (MS) is impaired and may result in either increases or decreases in body temperature. Disturbances in body temperature correlate with acute relapses, and for this reason, it is an important issue in everyday life of those who suffer from MS. Although rat experimental autoimmune encephalitis (EAE) appeared useful for the examination of current therapies against MS, it has not been thoroughly investigated in terms of body temperature. The purpose of this study was to examine the effect of EAE induction on thermal and motor behavior in the rats. Subcutaneous injection of encephalitogenic emulsion into both pads of hind feet of the Lewis rats provoked symptoms of EAE. Body temperature (T(b)) and motor activity of rats were measured using biotelemetry system. We report a significant increase in body temperature within 24 h prior to the EAE manifestation (12 h average of T(b) for EAE induced animals was higher by 1.07 ± 0.06 °C during day-time and by 0.5 ± 0.05 °C during night time in comparison to the control rats). On the other hand, the onset of EAE symptoms was associated with gradual decrease of body temperature, and during the first night-time T(b) was lower by 1.03 ± 0.08 °C in comparison to the control rats. The inhibition of the motor activity started from the night time, 2 days before EAE onset. On the basis of our data, we concluded that the pattern of body temperature changes after EAE induction may be considered as useful symptom (prodrom) to predict precisely the time of EAE onset. Furthermore, we suggest that EAE in rats may be a suitable model to study mechanism of body temperature alternations observed in MS patients.
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Garina DV, Smirnov AK, Kuz'mina V. The long-term effect of serotonin on the thermoregulatory behavior in juvenile cyprinidae (Cyprinus carpio and Carassius auratus). FISH PHYSIOLOGY AND BIOCHEMISTRY 2013; 39:1373-1376. [PMID: 23515758 DOI: 10.1007/s10695-013-9791-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/12/2012] [Accepted: 03/12/2013] [Indexed: 06/01/2023]
Abstract
The effect of serotonin after intracerebroventricular (ICV) injections in dosage of 0.3 and 0.15 μg/g of the body weight on the thermoregulatory behavior in juvenile carp Cyprinus carpio L. and goldfish Carassius auratus (L.) has been studied in two experiments of 10- to 11-day duration. It has been found that ICV injection of serotonin in dosage of 0.3 μg/g caused the initial decrease in preferred temperatures (PT) (2-3 days) followed by their further increase (4-8 days after the administration) in carp. ICV injection of serotonin in dosage of 0.15 μg/g caused more durable initial decrease in PT (2-8 days) followed by the increase of once (9-11 days of observation) in goldfish. The values of the ultimate preferred temperature in fish of the experimental group exceeded that in control specimens by 4.1 °C at the first experiment and by 3.1 °C in the second experiment. The data for the first time demonstrated long-term effect of a single ICV injection of serotonin on the thermoregulatory behavior in two closely related species of teleosts.
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Affiliation(s)
- D V Garina
- I.D. Papanin Institute for Biology of Inland Waters, Russian Academy of Sciences, Borok, Yaroslavl, Russia,
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He J, Xiu M, Tang X, Wang N, Xin Y, Li W, Chen Q. Thermoregulatory and metabolic responses to hypoxia in the oviparous lizard, Phrynocephalus przewalskii. Comp Biochem Physiol A Mol Integr Physiol 2013; 165:207-13. [PMID: 23500623 DOI: 10.1016/j.cbpa.2013.03.007] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2012] [Revised: 02/08/2013] [Accepted: 03/05/2013] [Indexed: 11/25/2022]
Abstract
The effects of hypoxia on behavioral thermoregulation, rate of heating and cooling, hysteresis of heart rate, and standard metabolic rate (SMR) were investigated in Phrynocephalus przewalskii, a small size toad headed lizard. Preferred temperature (T(b)) descended when lizards were exposed to severe hypoxia (8% O(2) and 6% O(2)) for 22 h, and lizards were able to maintain preferred T(b) after one week at 12% and 8% O(2) respectively. The period of heating increased after being treated with hypoxia (12% and 8% O(2)) for one week. Hysteresis of heart rate appeared at any given body temperature and oxygen level except at 39 °C and 40 °C at 8% O(2). SMR significantly increased after one-week acclimatization to 12% and 8% O(2) when ambient temperature (T(a)) was 25 °C, however, it did not change at 35 °C. Thus, we suggest that P. przewalskii has special thermoregulatory and metabolic mechanisms to acclimatize to the hypoxic environment.
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Affiliation(s)
- Jianzheng He
- Institute of Biochemistry and Molecular Biology, School of Life Sciences, Lanzhou University, 222 Tianshui South Road, Lanzhou, 730000, PR China
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11
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Baze MM, Schlauch K, Hayes JP. Gene expression of the liver in response to chronic hypoxia. Physiol Genomics 2010; 41:275-88. [PMID: 20103700 DOI: 10.1152/physiolgenomics.00075.2009] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Hypoxia is an important ecological, evolutionary, and biomedical stressor. While physiological acclimatization of mammals to hypoxia is well studied, the variation in gene expression that underlies acclimatization is not well studied. We acclimatized inbred mice for 32 days to hypoxic conditions that simulated altitudes of 1400, 3000, and 4500 m. We used oligonucleotide microarrays to measure changes in steady-state abundance of mRNA in the livers of these mice. Mice exposed to more severe hypoxia (simulated altitude of 4500 m) were smaller in mass and had higher hematocrit than mice exposed to less severe hypoxia. ANOVA and false discovery rate tests indicated that 580 genes were significantly differentially expressed in response to chronic hypoxia. Few of these 580 genes have previously been reported to respond to hypoxia. In contrast, many of these 580 genes belonged to same functional groups typically respond to acute hypoxia. That is, both chronic and acute hypoxia elicit changes in transcript abundance for genes involved in angiogenesis, glycolysis, lipid metabolism, carbohydrate metabolism, and protein amino acid phosphorylation, but the particular genes affected by the two types of hypoxia were mostly different. Numerous genes affecting the immune system were differentially expressed in response to chronic hypoxia, which supports recently proposed hypotheses that link immune function and hypoxia. Furthermore, our results discovered novel elevated mRNA abundance of genes involved in hematopoiesis and oxygen transport not reported previously, but consistent with extreme hematocrits found in hypoxic mice.
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Affiliation(s)
- Monica M Baze
- Program in Ecology, Evolution and Conservation Biology and Department of Biology, and
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12
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Levesque DL, Tattersall GJ. Seasonal changes in thermoregulatory responses to hypoxia in the Eastern chipmunk (Tamias striatus). ACTA ACUST UNITED AC 2009; 212:1801-10. [PMID: 19482997 DOI: 10.1242/jeb.027094] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Mammalian heterotherms are known to be more tolerant of low oxygen levels than homeotherms. However, heterotherms demonstrate extreme seasonality in daily heterothermy and torpor expression. Because hypoxia depresses body temperature (T(b)) and metabolism in mammals, it was of interest to see if seasonal comparisons of normothermic animals of a species capable of hibernation produce changes in their responses to hypoxia that would reflect a seasonal change in hypoxia tolerance. The species studied, the Eastern chipmunk (Tamias striatus, Linnaeus 1758), is known to enter into torpor exclusively in the winter. To test for seasonal differences in the metabolic and thermoregulatory responses to hypoxia (9.9 kPa), flow-through respirometry was used to compare oxygen consumption, minimum thermal conductance and T(b) under fixed ambient temperature (T(a)) conditions whereas a thermal gradient was used to assess selected T(a) and T(b) in response to hypoxia, in both summer- and winter-acclimated animals. No differences were observed between seasons in resting metabolism or thermal conductance in normoxic, normothermic animals. Providing the animals with a choice of T(a) in hypoxia attenuated the hypoxic drop in T(b) in both seasons, suggesting that the reported fall in T(b) in hypoxia is not fully manifested in the behavioural pathways responsible for thermoregulation in chipmunks. Instead, T(b) in hypoxia tends to be more variable and dependent on both T(a) and season. Although T(b) dropped in hypoxia in both seasons, the decrease was less in the winter with no corresponding decrease in metabolism, indicating that winter chipmunks are more tolerant to hypoxia than summer animals.
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Affiliation(s)
- Danielle L Levesque
- Department of Biological Sciences, Brock University, St Catharines, ON, Canada, L2S 3A1
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13
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Role of brain nitric oxide in the thermoregulation of broiler chicks. Comp Biochem Physiol A Mol Integr Physiol 2009; 154:204-10. [DOI: 10.1016/j.cbpa.2009.06.005] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2008] [Revised: 06/06/2009] [Accepted: 06/07/2009] [Indexed: 12/11/2022]
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14
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Role of preoptic opioid receptors in the body temperature reduction during hypoxia. Brain Res 2009; 1286:66-74. [DOI: 10.1016/j.brainres.2009.06.039] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2009] [Revised: 06/10/2009] [Accepted: 06/13/2009] [Indexed: 11/16/2022]
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15
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Guerra AR, Gargaglioni LH, Noronha-De-Souza CR, Abe AS, Branco LG, Bícego KC. Role of central nitric oxide in behavioral thermoregulation of toads during hypoxia. Physiol Behav 2008; 95:101-7. [DOI: 10.1016/j.physbeh.2008.05.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2008] [Accepted: 05/05/2008] [Indexed: 10/22/2022]
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16
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Atchley DS, Foster JA, Bavis RW. Thermoregulatory and metabolic responses of Japanese quail to hypoxia. Comp Biochem Physiol A Mol Integr Physiol 2008; 151:641-50. [PMID: 18727957 DOI: 10.1016/j.cbpa.2008.08.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2008] [Revised: 08/04/2008] [Accepted: 08/05/2008] [Indexed: 10/21/2022]
Abstract
Common responses to hypoxia include decreased body temperature (Tb) and decreased energy metabolism. In this study, the effects of hypoxia and hypercapnia on Tb and metabolic oxygen consumption (VO2) were investigated in Japanese quail (Coturnix japonica). When exposed to hypoxia (15, 13, 11 and 9% O2), Tb decreased only at 11% and 9% O2 compared to normoxia; quail were better able to maintain Tb during acute hypoxia after a one-week acclimation to 10% O2. VO2 also decreased during hypoxia, but at 9% O2 this was partially offset by increased anaerobic metabolism. Tb and VO2 responses to 9% O2 were exaggerated at lower ambient temperature (Ta), reflecting a decreased lower critical temperature during hypoxia. Conversely, hypoxia had little effect on T(b) or VO2 at higher Ta (36 degrees C). We conclude that Japanese quail respond to hypoxia in much the same way as mammals, by reducing both Tb and VO2. No relationship was found between the magnitudes of decreases in Tb and VO2 during 9% O2, however. Since metabolism is the source of heat generation, this suggests that Japanese quail increase thermolysis to reduce Tb. During hypercapnia (3, 6 and 9% CO2), Tb was reduced only at 9% CO2 while VO2 was unchanged.
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Affiliation(s)
- Dylan S Atchley
- Department of Biology, Bates College, Lewiston, ME 04240 USA
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Lefter R, Doan VD, Joseph V. Contrasting effects of estradiol and progesterone on respiratory pattern and hypoxic ventilatory response in newborn male rats. Respir Physiol Neurobiol 2008; 164:312-8. [PMID: 18760385 DOI: 10.1016/j.resp.2008.07.026] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2008] [Revised: 07/29/2008] [Accepted: 07/30/2008] [Indexed: 11/28/2022]
Abstract
We tested the hypothesis that postnatal exposure to progesterone or estradiol exerts distinct effects on respiratory control, apnea frequency, and on hypoxic ventilatory response (HVR). To this aim, we assessed breathing pattern using whole body plethysmography in normoxia and during a sustained hypoxic exposure (10% O(2)-30min) in 10-day-old male rats raised by dams implanted with osmotic minipumps delivering either estradiol (E(2), 7.0microgday(-1)), estradiol+progesterone (E(2)+P, 7.0+70microgday(-1)) or vehicle (propylene glycol) at a regular flow rate throughout postnatal days 1-14. Compared to vehicle, E(2) and E(2)+P pups had a reduced ventilation, metabolic rate and rectal temperature. HVR was specifically increased in E(2)+P pups compared to controls and E(2) pups. On the contrary, both E(2) and E(2)+P pups did not reduced metabolism as much as controls during hypoxic exposure, and the decrease in rectal temperature was abolished. Surprisingly, E(2)+P pups showed a dramatic elevation of sigh frequency, while progesterone (in E(2)+P compared to E(2) and Veh pups) reduced apnea frequency. These findings are relevant to better understand the role of placental steroids on respiratory and metabolic control during early development in rats, and could ultimately contribute to a better understanding of specific respiratory control disorders in preterm neonates, which are chronically deprived from placental steroids exposure.
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Affiliation(s)
- Raluca Lefter
- Department of Pediatrics, Laval University, Centre de Recherche (D0-711), Hôpital St-François d'Assise, 10 rue de l'Espinay, Quebec G1L 3L5, Canada
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Heydarnejad MS. Survival of Paramecium caudatum at various pH values and under normoxic and hypoxic conditions. Pak J Biol Sci 2008; 11:392-397. [PMID: 18817161 DOI: 10.3923/pjbs.2008.392.397] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
The objective of this study was to determine the survival of Paramecium caudatum, a protozoan ciliate, with different pH under normoxic and hypoxic conditions. P. caudatum was exposed to 18 treatments (in triplicate) of varying pH (4, 4.7, 5.7, 6.7, 7.7, 8.7, 9.7, 10.7 and 11.7) with two different conditions of normoxic and hypoxic. Survival was examined every second day for three weeks. P. caudatum mortality was 100% immediately when exposed to pH 4, 10.7 and 11.7 either in normoxic or hypoxic conditions, whereas at other pH values tested this ciliate could survive mostly under hypoxic conditions. The results suggest that under hypoxic condition, 4.7-6.7 is the best pH range for survival of this species.
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Affiliation(s)
- M Saeed Heydarnejad
- Laboratory of Protozoology, Department of Biology, Shahrekord University, Shahrekord-88186, P.O. Box 115, Iran
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19
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Baig MS, Joseph V. Age specific effect of MK-801 on hypoxic body temperature regulation in rats. Respir Physiol Neurobiol 2007; 160:181-6. [PMID: 17964229 DOI: 10.1016/j.resp.2007.09.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2007] [Revised: 09/14/2007] [Accepted: 09/17/2007] [Indexed: 10/22/2022]
Abstract
Hypoxic exposure produces a consistent decrease of rectal temperature (Tb), which is recognized as a potent protective response. While some of the neural mechanisms underlying this response have recently been described, it remains poorly known how these mechanisms evolve during post-natal development. We recently reported that in rat pups NMDA glutamate receptor limits Tb drop upon hypoxic exposure, an effect that has not been reported by others in adult rats. Accordingly, we tested the hypothesis that the implication of NMDA receptors on temperature control during hypoxic exposure evolves during development. To this aim, we evaluated the hypoxic (30 min - 12% O(2)) responses of Tb, metabolic rate, and ventilation in rats after injection of vehicle, or the NMDA receptor antagonist MK-801, at different ages (post-natal days 4, 10, 20 and 2-3 month-old - P4, P10, P20 and P60). MK-801 amplified the magnitude of the hypoxic-induced Tb drop in P4, P10 and P20 rats, but this effect was not apparent in adults. In P20 rats MK-801 tripled the hypoxic induced Tb drop, which was 0.5 degrees C in control and 1.4 degrees C in treated rats (p<0.0001). This effect was specific to temperature regulation, and was not accompanied by similar changes of other recorded parameters. MK-801 induced a significant decrease of the hypoxic ventilatory response in adults only. We conclude that NMDA glutamate receptor acts as a counter-regulatory factor that limits the hypoxic-induced drop of rectal temperature during post-natal development in rats.
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Affiliation(s)
- Mirza Shafiulla Baig
- Department of Pediatrics, Laval University, Centre de Recherche CHUQ, Hôpital St-François d'Assise, Local D0-711, 10 Rue de l'Espinay, Quebec, QC G1L 3L5, Canada
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Bicego KC, Barros RCH, Branco LGS. Physiology of temperature regulation: comparative aspects. Comp Biochem Physiol A Mol Integr Physiol 2006; 147:616-639. [PMID: 16950637 DOI: 10.1016/j.cbpa.2006.06.032] [Citation(s) in RCA: 156] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2005] [Revised: 05/28/2006] [Accepted: 06/16/2006] [Indexed: 10/24/2022]
Abstract
Few environmental factors have a larger influence on animal energetics than temperature, a fact that makes thermoregulation a very important process for survival. In general, endothermic species, i.e., mammals and birds, maintain a constant body temperature (Tb) in fluctuating environmental temperatures using autonomic and behavioural mechanisms. Most of the knowledge on thermoregulatory physiology has emerged from studies using mammalian species, particularly rats. However, studies with all vertebrate groups are essential for a more complete understanding of the mechanisms involved in the regulation of Tb. Ectothermic vertebrates-fish, amphibians and reptiles-thermoregulate essentially by behavioural mechanisms. With few exceptions, both endotherms and ectotherms develop fever (a regulated increase in Tb) in response to exogenous pyrogens, and regulated hypothermia (anapyrexia) in response to hypoxia. This review focuses on the mechanisms, particularly neuromediators and regions in the central nervous system, involved in thermoregulation in vertebrates, in conditions of euthermia, fever and anapyrexia.
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Affiliation(s)
- Kênia C Bicego
- Department of Animal Physiology and Morfology, College of Agricultural and Veterinarian Sciences, Sao Paulo State University, Jaboticabal, São Paulo, Brazil.
| | - Renata C H Barros
- Department of General and Specialized Nursing, Nursing School of Ribeirão Preto, University of São Paulo, 14040-904, Ribeirão Preto, São Paulo, Brazil
| | - Luiz G S Branco
- Department of Morphology, Estomatology and Physiology, Dental School of Ribeirão Preto, University of São Paulo, 14040-904, Ribeirão Preto, São Paulo, Brazil
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