title: [Effects of low gravity preconditioning on rat learning and memory impairment induced by high gravity exposure].
abstract: OBJECTIVE
  To study the protective effects of low gravity preconditioning against learning and memory function impairment induced by high gravity exposure in rats.
  
  
  METHODS
  Twenty-four male SD rats were randomized equally into control group, high gravity exposure group (+10 Gz/3 min) and low gravity preconditioning group (LGP group, preconditioned by a daily exposure to +4 Gz/3 min for 3 days before +10 Gz/3 min exposure). Both the learning and memory abilities of the rats in the 3 groups were examined after +10 Gz/3 min exposure.
  
  
  RESULTS
  In open field test, the rats exposed to +10 Gz/3 min, in comparison with the control rats, exhibited significantly declined total square-crossing and rearing (SCR) on days 0 and 2 (P<0.05), with also significantly prolonged stay in the central square at 0 d(P<0.01). In the low gravity preconditioned rats, SCR declined and length of stay in the central square increased significantly on day 0 (P<0.01). Compared with the rats in +10 Gz/3 min group, the rats in the LGP group showed decreased length of stay in the central square on day 2, and such changes was statistically significant on day 6 (P<0.05), but there was no difference in SCR at all time points. In Y-maze test, the number of times of right reaction (RR) decreased and the reaction time (RT) increased significantly in +10 Gz/3min group compared with those of the control group (P<0.01), whereas no significant differences were found between the control group and LGP group. Compared with +10 Gz/3 min group, the RR was increased (P<0.01) and RT shortened significantly (P<0.01) in LGP group. In the step-through test, the latent time (LT) increased (P<0.05) on day 0 but was then shortened significantly on day 6 in + 10 Gz/3min group (P<0.01), and no difference was found between LGP group and the control group. LT on day 6 increased significantly (P<0.01) in LGP group as compared with the +10 Gz/3 min group.
  
  
  CONCLUSIONS
  High gravity exposure-induced rat learning and memory impairment can be markedly improved by lower gravity preconditioning.
authors.affiliation: Department of Aerospace Biodynamics, Fourth Military Medical University, Xi'an 710032, China. caoxinsheng@163.net
authors.forename: Xin-Sheng
authors.initials: XS
authors.lastname: Cao
authors.forename: Xing-Yu
authors.initials: XY
authors.lastname: Wu
authors.forename: Xi-Qing
authors.initials: XQ
authors.lastname: Sun
authors.forename: Ting-Song
authors.initials: TS
authors.lastname: Liu
mesh_terms: D000054:Acceleration / Q000009:adverse effects*; D000818:Animals; D018471:Hypergravity / Q000009:adverse effects; D002534:Hypoxia, Brain / Q000473:pathology / Q000503:physiopathology*; D019194:Ischemic Preconditioning; D007858:Learning / Q000502:physiology*; D008297:Male; D018782:Maze Learning / Q000502:physiology; D008568:Memory / Q000502:physiology*; D011897:Random Allocation; D051381:Rats; D017207:Rats, Sprague-Dawley