title: Strain variation in the adaptation of C57Bl6 and BALBc mice to chronic hypobaric hypoxia.
abstract: The interplay of environmental and genetic factors may lead to a spectrum of physiological and behavioral outcomes. How environmental stress factors interact with the diverse mouse genomes is still poorly understood and elucidating the underlying interactions requires specific stress models that can target integrated physiological systems. Here, we employ behavioral tests and whole-body plethysmography to examine the effects of 12 weeks of simulated high altitude (HA) exposure on two inbred mouse strains, BALBc and C57Bl6. We find that HA induced- weight loss recovers at significantly different rates in these two strains. Even at 12 weeks, however, both strains fail to reach body weight levels of controls. Performance on two motor tasks, rotarod and treadmill, improve with HA exposure but more prominently in BALBc mice. Whole-body plethysmography outcomes indicate that compensation to chronic HA includes increased respiratory frequencies and tidal volumes in both strains. However, the effects on tidal volume are significantly greater in BALBc mice and showed a biphasic course. Whole- body metabolic rates are also increased in both strains with prolonged HA exposure, but were more pronounced in BALBc mice suggestive of less successful adaptation in this strain. These adaptations occur in the absence of gross pathological changes in all major organs. Together these results indicate that chronic HA exposure results in environmental stressors that impact the specific physiological responses of BALBc more than C57Bl6 mice. Thus, these strains provide a promising platform for investigating how genetic backgrounds can differentially reinforce the effects of long-lasting environmental stressors and their potential to interact with psychological stressors.
authors: F. Edward Hébert School of Medicine, Department of Anatomy, Physiology and Genetics, Uniformed Services Univ. of the Health Sciences, Bethesda, MD, United States.
authors: Nathan P
authors: NP
authors: Cramer
authors: F. Edward Hébert School of Medicine, Department of Anatomy, Physiology and Genetics, Uniformed Services Univ. of the Health Sciences, Bethesda, MD, United States.
authors: Xiufen
authors: X
authors: Xu
authors: Division of Comparative Pathology Armed Forces Radiobiology Research Institute, Uniformed Services Univ. of the Health Sciences, Bethesda, MD, United States.
authors: Christine
authors: C
authors: Christensen
authors: Division of Physiology, Johns Hopkins University Bloomberg School of Public Health, Baltimore, MD, United States.
authors: Alexis
authors: A
authors: Bierman
authors: F. Edward Hébert School of Medicine, Department of Anatomy, Physiology and Genetics, Uniformed Services Univ. of the Health Sciences, Bethesda, MD, United States; Division of Physiology, Johns Hopkins University Bloomberg School of Public Health, Baltimore, MD, United States.
authors: Clarke G
authors: CG
authors: Tankersley
authors: F. Edward Hébert School of Medicine, Department of Anatomy, Physiology and Genetics, Uniformed Services Univ. of the Health Sciences, Bethesda, MD, United States. Electronic address: zygmunt.galdzicki@usuhs.edu.
authors: Zygmunt
authors: Z
authors: Galdzicki
mesh_terms: D000222:Adaptation, Physiological; D000532:Altitude Sickness / Q000378:metabolism* / Q000503:physiopathology* / Q000534:rehabilitation; D000818:Animals; D005080:Exercise Test; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D009043:Motor Activity; D010101:Oxygen Consumption; D010805:Physical Conditioning, Animal / Q000379:methods*; D010991:Plethysmography; D012119:Respiration; D013045:Species Specificity; D013997:Time Factors
keywords: Adaptation; High altitude; Hypobaria; Hypoxia; Mouse strains; Stress