Experimental Biology 1997 Symposium on Neurobiology of Thermoregulation: Role of Stress: EFFECT OF GENDER ON THERMOREGULATION AND SURVIVAL OF HYPOXIC RATS

Wood, Stephen C.; Stabenau, Erich K.

doi:10.1111/j.1440-1681.1998.tb02196.x

Cited by 37 publications

(7 citation statements)

References 18 publications

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“…Because gender differences have been previously reported on the adaptive responses of rats to hypoxia [41], female rats, which are more tolerant to hypoxia than males, were used in the present study. All animals were housed one per cage in a thermoneutral environment (22±2 °C) on a 12:12-h photoperiod and were provided with food and water ad libitum.…”

Section: Methodsmentioning

confidence: 99%

Ambient hypoxia enhances the loss of muscle mass after extensive injury

Chaillou

Koulmann

A³

et al. 2013

Pflugers Arch - Eur J Physiol

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Hypoxia induces a loss of skeletal muscle mass and alters myogenesis in vitro, but whether it affects muscle regeneration in vivo following injury remains to be elucidated. We hypothesized that hypoxia would impair the recovery of muscle mass during regeneration. To test this hypothesis, the soleus muscle of female rats was injured by notexin and allowed to recover for 3, 7, 14, and 28 days under normoxia or hypobaric hypoxia (5,500 m) conditions. Hypoxia impaired the formation and growth of new myofibers and enhanced the loss of muscle mass during the first 7 days of regeneration, but did not affect the final recovery of muscle mass at 28 days. The impaired regeneration under hypoxic conditions was associated with a blunted activation of mechanical target of rapamycin (mTOR) signaling as assessed by p70S6K and 4E-BP1 phosphorylation that was independent of Akt activation. The decrease in mTOR activity with hypoxia was consistent with the increase in AMP-activated protein kinase activity, but not related to the change in regulated in development and DNA response 1 protein content. Hypoxia increased the mRNA levels of the atrogene muscle ring finger-1 after 7 days of regeneration, though muscle atrophy F box transcript levels remained unchanged. The increase in MyoD and myogenin mRNA expression with regeneration was attenuated at 7 days with hypoxia. In conclusion, our results support the notion that the enhanced loss of muscle mass observed after 1 week of regeneration under hypoxic conditions could mainly result from the impaired formation and growth of new fibers resulting from a reduction in protein synthesis and satellite cell activity.

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Section: Methodsmentioning

confidence: 99%

Ambient hypoxia enhances the loss of muscle mass after extensive injury

Chaillou

Koulmann

A³

et al. 2013

Pflugers Arch - Eur J Physiol

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“…Studies conducted on the metabolic alterations induced by LHTH have been primarily conducted using male rats. However, we voluntarily designed our study using females to limit the deleterious effect of hypoxia on the energy balance (Wood and Stabenau, 1998), which is often a bias in severe and prolonged exposure of males to hypoxia. In the model used here, we observed no difference in body weight, often induced by hypoxia or training in male rats (Foright et al, 2020), limiting confounding metabolic factors due to differences in food intake.…”

Section: Strengths and Limitationsmentioning

confidence: 99%

Endurance Is Improved in Female Rats After Living High-Training High Despite Alterations in Skeletal Muscle

Malgoyre¹,

Prola²,

A³

et al. 2021

Front. Sports Act. Living

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Altitude camps are used during the preparation of endurance athletes to improve performance based on the stimulation of erythropoiesis by living at high altitude. In addition to such whole-body adaptations, studies have suggested that high-altitude training increases mitochondrial mass, but this has been challenged by later studies. Here, we hypothesized that living and training at high altitude (LHTH) improves mitochondrial efficiency and/or substrate utilization. Female rats were exposed and trained in hypoxia (simulated 3,200 m) for 5 weeks (LHTH) and compared to sedentary rats living in hypoxia (LH) or normoxia (LL) or those that trained in normoxia (LLTL). Maximal aerobic velocity (MAV) improved with training, independently of hypoxia, whereas the time to exhaustion, performed at 65% of MAV, increased both with training (P = 0.009) and hypoxia (P = 0.015), with an additive effect of the two conditions. The distance run was 7.98 ± 0.57 km in LHTH vs. 6.94 ± 0.51 in LLTL (+15%, ns). The hematocrit increased >20% with hypoxia (P < 0.001). The increases in mitochondrial mass and maximal oxidative capacity with endurance training were blunted by combination with hypoxia (−30% for citrate synthase, P < 0.01, and −23% for Vmax glut−succ, P < 0.001 between LHTH and LLTL). A similar reduction between the LHTH and LLTL groups was found for maximal respiration with pyruvate (−29%, P < 0.001), for acceptor-control ratio (−36%, hypoxia effect, P < 0.001), and for creatine kinase efficiency (−48%, P < 0.01). 3-hydroxyl acyl coenzyme A dehydrogenase was not altered by hypoxia, whereas maximal respiration with Palmitoyl-CoA specifically decreased. Overall, our results show that mitochondrial adaptations are not involved in the improvement of submaximal aerobic performance after LHTH, suggesting that the benefits of altitude camps in females relies essentially on other factors, such as the transitory elevation of hematocrit, and should be planned a few weeks before competition and not several months.

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“…Thermoregulation is an energetically demanding process in small mammals and many such species reduce T b to facilitate metabolic savings in hypoxia ( Barros et al, 2001 ; Wood and Gonzales, 1996 ; Wood and Stabenau, 1998 ). Therefore, we also measured T b to gain insight into the regulation of thermogenesis in hypoxia and hypercapnia.…”

Section: Resultsmentioning

confidence: 99%

Physiological responses to hypoxia are constrained by environmental temperature in heterothermic tenrecs

Devereaux

Rubio

Breukelen

et al. 2023

Journal of Experimental Biology

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Malagasy tenrecs are placental hibernating mammals who seal the entrances to their burrows and hibernate either singly or in groups for 8-9 months, which is likely to create a hypoxic and hypercapnic burrow environment. Therefore, we hypothesized that tenrecs are tolerant to environmental hypoxia and hypercapnia. Many hypoxia- and hypercapnia-tolerant fossorial mammals respond to hypoxia by decreasing metabolic rate and thermogenesis and have blunted ventilatory responses to both environmental hypoxia and hypercapnia. However, tenrecs exhibit extreme metabolic and thermoregulatory plasticity, which exceeds that of most heterothermic mammals and approaches that of ectothermic reptiles. Thus, we predicted that tenrecs would have abnormal physiological responses to hypoxia and hypercapnia relative to other fossorial mammals. To test this, we exposed common tenrecs (Tenrec ecaudatus) to moderate and severe hypoxia (9 and 4% O2) or hypercapnia (5 and 10% CO2) in either 28 or 16°C while non-invasively measuring metabolic rate, thermogenesis, and ventilation. We found that tenrecs exhibit robust metabolic decreases in both hypoxia and hypercapnia. Furthermore, tenrecs have blunted ventilatory responses to both hypoxia and hypercapnia, and these responses are highly temperature sensitive such that they are reduced or absent in 16°C. Thermoregulation was highly variable in 16°C but constrained in 28°C across all treatment conditions and was not impacted by hypoxia or hypercapnia, unlike in other heterothermic mammals. Taken together, our results indicate that physiological responses to hypoxia and hypercapnia in tenrecs are highly dependent on environmental temperature and differ from other mammalian heterotherms.

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Experimental Biology 1997 Symposium on Neurobiology of Thermoregulation: Role of Stress: EFFECT OF GENDER ON THERMOREGULATION AND SURVIVAL OF HYPOXIC RATS

Cited by 37 publications

References 18 publications

Ambient hypoxia enhances the loss of muscle mass after extensive injury

Ambient hypoxia enhances the loss of muscle mass after extensive injury

Endurance Is Improved in Female Rats After Living High-Training High Despite Alterations in Skeletal Muscle

Physiological responses to hypoxia are constrained by environmental temperature in heterothermic tenrecs

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