title: [Combined simulated weightlessness and noise affect cell cycles and composition in rat thymocytes].
abstract: OBJECTIVE
  To observe the combined effects of simulated weightlessness and noise on the cell cycles of thymocytes and cell compositions of thymus in rats and to explore the possible mechanism of immune function depression in space flight.
  
  
  METHODS
  SD rats were stimulated by simulated weightlessness and/or noise. On the 3rd, 7th and 14th day, the rats were weighed and then killed. The thymuses were taken, weighed and cell suspensions were made. Cell cycles and compositions in thymocytes were analyzed by flow cytometry.
  
  
  RESULTS
  Compared with control group, the weights of rats were reduced in combined group and simulated weightlessness group, but the weights of rats increased or did not change in noise group. Rats in the three groups showed thymus atrophy. The ratio of cells increased in G0/G1 phase and decreased in S and G2/M phases. The ratios of CD4(-) CD8(-), CD4(+) CD8(-) and CD4(-) CD8(+) T lymphocytes increased and CD4(+) CD8(+) T lymphocytes decreased. However, these changes occurred at different time points in different groups.
  
  
  CONCLUSIONS
  Simulated weightlessness and noise have significant effects on thymus, but the severity are different. The combined factors have superimposed effects. Maybe this is one of the reasons for depressed functions of T lymphocytes in space flight.
authors.affiliation: Center for Special Medicine and Experimental Research, 306th Hospital of PLA, Beijing 100101, China.
authors.forename: Shaoyan
authors.initials: S
authors.lastname: Si
authors.affiliation: Center for Special Medicine and Experimental Research, 306th Hospital of PLA, Beijing 100101, China. *Corresponding authors, E-mail: yf2000412@163.com.
authors.forename: Shujun
authors.initials: S
authors.lastname: Song
authors.affiliation: Center for Special Medicine and Experimental Research, 306th Hospital of PLA, Beijing 100101, China.
authors.forename: Nan
authors.initials: N
authors.lastname: Hua
authors.affiliation: Department of Otorhinolaryngology, 306th Hospital of PLA, Beijing 100101, China.
authors.forename: Haolun
authors.initials: H
authors.lastname: Han
authors.affiliation: Center for Special Medicine and Experimental Research, 306th Hospital of PLA, Beijing 100101, China.
authors.forename: Bingxin
authors.initials: B
authors.lastname: Xu
authors.affiliation: Department of Otorhinolaryngology, 306th Hospital of PLA, Beijing 100101, China.
authors.forename: Gang
authors.initials: G
authors.lastname: Wang
authors.affiliation: Department of Otorhinolaryngology, 306th Hospital of PLA, Beijing 100101, China.
authors.forename: Chi
authors.initials: C
authors.lastname: Zhang
authors.affiliation: Department of Otorhinolaryngology, 306th Hospital of PLA, Beijing 100101, China. *Corresponding authors, E-mail: shuj80@126.com.
authors.forename: Wei
authors.initials: W
authors.lastname: Wu
mesh_terms: D000818:Animals; D001835:Body Weight / Q000502:physiology; D016516:CD4-CD8 Ratio; D002453:Cell Cycle / Q000502:physiology*; D005434:Flow Cytometry; D009622:Noise; D009929:Organ Size / Q000502:physiology; D017207:Rats, Sprague-Dawley; D016176:T-Lymphocyte Subsets / Q000166:cytology / Q000378:metabolism; D060168:Thymocytes / Q000166:cytology / Q000378:metabolism*; D013950:Thymus Gland / Q000166:cytology / Q000254:growth & development; D018474:Weightlessness Simulation / Q000379:methods*