Effects of high-altitude environment on cognitive function and ultrastructure in CA1 region of hippocampus of rats after sleep deprivation

Abstract

Objective To investigate the effects of high-altitude environment on cognitive function and ultrastructure in CA1 region of the hippocampus of Wistar rats in sleep deprivation (SD).  Methods SD was induced in Wistar rats by employing "flower pot" technique. Sixty-four rats were randomly divided into 2 groups: Lanzhou group (at an altitude of 1520 m) and Kekexili group (at an altitude of 4767 m), and each group was further divided into 4 subgroups according to the time of SD (0, 1, 3 and 5 d). The behaviors of rats were studied by Morris water maze test at given time points. The ultrastructure of hippocampal neurons was observed by transmission electron microscope (TEM).  Results 1) Compared with Lanzhou group, rat behavior of Kekexili group presented excitement-irritation-suppression changes with the extension of SD time, but the extent was weakened gradually, and time of sleepiness increased obviously. 2) Compared with Lanzhou group, neurons in CA1 region of hippocampus showed enlarged cell body, disappeared nuclear membrane, shrunken nuclei and decreased organelle. End-feet of glia cells sticking to capillaries swelled and ruptured, and the typical synaptic structure disappeared. 3) Morris water maze test: as compared with Lanzhou group, the escape latency of Kekexili group prolonged (P < 0.05, for all), the ability of distance exploration increased (P < 0.05, for all), and the times across plot decreased (P < 0.05, for all) in 1, 3 and 5 d of SD.  Conclusions High-altitude environment may significantly influence the cognitive function of rats in SD, and there was close correlation between the cognitive disorders and the changes in the ultrastructure of hippocampal CA1 region.

doi: 10.3969/j.issn.1672-6731.2014.04.012