title: Telomeres are elongated in rats exposed to moderate altitude.
abstract: BACKGROUND
  Leukocyte telomere length has been shown to be associated with life span. Hypoxia-associated changes of telomere length have been detected in cell cultures, but no in vivo studies have reported the changes of telomere length under different hypoxic conditions. This study aimed to evaluate the effects of altitude on telomere length in rat leukocytes.
  
  
  METHODS
  One hundred and ten male Wistar rats were randomized into 3 groups and maintained at sea-level (altitude of 10 m) (SL group, n=10), moderate altitude (2,260 m) (MA group, n=50), or simulated high altitude (5,000 m (SHA group, n=50). The last two groups were further divided into 5 subgroups and exposed to hypoxia for 1, 3, 7, 15, or 30 days (n=10). The leukocyte telomere length, hemoglobin concentration, red blood cell count, hematocrit, and plasma levels of telomerase reverse transcriptase (TERT), hypoxia-inducible factor 1α (HIF-1α), malondialdehyde (MDA) and superoxide dismutase (SOD) were measured.
  
  
  RESULTS
  Leukocyte telomere length was significantly longer in the MA group than in the SL or SHA groups, and the TERT expression changed in a similar manner as the leukocyte telomere length. However, HIF-1α level was significantly higher in both MA and SHA groups than the SL group. SOD level was decreased and MDA level was elevated in SHA group.
  
  
  CONCLUSIONS
  The telomere length of blood leukocytes is elongated at a moderate altitude, but not at a high altitude. A mild hypoxic state may increase telomere length.
authors.forename: Yaping
authors.initials: Y
authors.lastname: Wang
authors.forename: Wen-di
authors.initials: WD
authors.lastname: Zhou
authors.forename: Yingzhong
authors.initials: Y
authors.lastname: Yang
authors.forename: Lan
authors.initials: L
authors.lastname: Ma
authors.forename: Yanxia
authors.initials: Y
authors.lastname: Zhao
authors.forename: Zhenzhong
authors.initials: Z
authors.lastname: Bai
authors.affiliation: Research Center for High Altitude Medical Sciences, University School of Medicine, 810001 Xining, Qinghai, China. geriligao@hotmail.com.
authors.forename: Ri-Li
authors.initials: RL
authors.lastname: Ge
mesh_terms: D000531:Altitude; D000818:Animals; D000860:Hypoxia / Q000097:blood*; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000097:blood; D007962:Leukocytes / Q000737:chemistry / Q000502:physiology; D008297:Male; D008315:Malondialdehyde / Q000097:blood; D051381:Rats; D017208:Rats, Wistar; D013482:Superoxide Dismutase / Q000097:blood; D019098:Telomerase / Q000097:blood; D016615:Telomere / Q000737:chemistry*
chemical_list: D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D008315:Malondialdehyde; D013482:Superoxide Dismutase; D019098:Telomerase