Effects Of Repeated High +Gz Exposures And Push-pull Maneuver On GFAP Expressions Of Astrocytes In Rat Brain

Brain function can be influenced by repeated durative high +Gz exposures and push-pull maneuver, which is a severe threat to the aviation safety. A few studies on the mechanisms of brain injury induced by repeated high +Gz exposures and push-pull maneuver have been reported, but most of them emphasized on the aspect of the injured nerve cells; however, ignored the roles of the glial cells in brain injury, especially the roles of astrocytes. The quantity of the glial cells is approximately 10-50 times than that of the nerve cells. In the glial cells, the number of the astrocytes ranks first and the distribution of them is considerably widespread, therefore, they play a vital role in performing the majority of the functions of the glial cells. In these past years, more and more attentions have been paid to the roles of the astrocytes in brain injury. When brain injury induced by cerebral ischemia appears, swell, degeneration, apoptosis, or necrosis will appear to some extent in nerve cells. At the same time, astrocytes can be activated due to the stimulus of cerebral ischemia, and in turn there will appear a series of physiological and biochemical reactions in astrocytes, which have certain protection to nerve cells being injuried. However, the studies on activation and effects of repeated high +Gz exposures and push-pull maneuver as two kinds of stimulus on astrocytes were scarcely reported.The astrocytes have important function in the course of generation and development of brain injury induced by repeated high +Gz exposures and push-pull maneuver possibly. We supposed that astrocytes could be activated due to brain injury induced by repeated high +Gz exposures and push-pull maneuver, and produce some protective cytokines benefiting nerve cells, but the scientific experimentation gist was scanty. The purpose of the present study was to observe the effects of repeated high +Gz exposures and push-pull maneuver on astrocytes in rat brain and the characteristics of changes of astrocytes in brain, and to offer new theoretical evidence for further elucidation of the mechanism of brain injury induced by repeated high +Gz exposures and push-pull maneuver. Male Sprague-Dawley rats offered by the Animal Center of the FourthMilitary Medical University were exposed to repeated high +Gz exposures and push-pull maneuver animal centrifuge. The exposed rats were infused and the rats'brains were removed, then made into paraffin sections. G1ial fibri11ary acidic protein(GFAP) expressions and the characteristics of changes in rat parietal cortex , hippocampus and cerebral ganglion after repeated high +Gz exposures and push-pull maneuver were determined by immunohistochemical staining.The main findings are as follows:1. repeated +10Gz/45s exposures may induce significant increase of GFAP expression in parietal cortex and hippocampus of rat.We observed the effects of repeated +10Gz/45s exposures 5 times on GFAP expression of astrocytes in rat brain. The results showed that, as compared with control group, the number of GFAP-positive cells increased significantly (P﹤0.05) in the rat parietal cortex and hippocampus 1d and 2d after repeated +Gz exposure, the most of which belonged to that of weakly positive and thin type; Compared with control group, the number of GFAP-positive cells increased further (P﹤0.01) in the rat parietal cortex and hippocampus 4d and 6d after +Gz exposure, the most of which belonged to that of medium positive, and the fat GFAP-positive cells increased.It is suggested that repeated +10Gz/45s exposures may induce significant increase of GFAP expression in parietal cortex and hippocampus of rat.2. +10Gz/ 3min exposure may induce significant increase of GFAP expression in rat parietal cortex, hippocampus and cerebral ganglion. GFAP expression increased more significantly after push-pull maneuver than after +10Gz/3min exposure. We observed the effects of push-pull maneuver on GFAP expression of astrocytes in rat brain.The rats of push-pull maneuver group were exposed -3Gz/1min firstly, with that exposed +10Gz/3min. The rats of +10Gz/3min group were exposed +10Gz/3min only. The results showed that, as compared with control group, the GFAP positive reaction was medium strength and the number of GFAP-positive cells increased significantly (P﹤0.01) in the parietal cortex ,hippocampus and cerebral ganglion 6h after +10Gz/3min exposure, the most of which belonged to that of medium positive thin type; 1d, 2d, 4d, and 6d after +10Gz exposure, the GFAP positive reaction enhanced further and the number of GFAP-positive cells increased further. Compared with +10Gz exposure group and control group, the GFAP positive reaction was stronger and the number of GFAP-positive cells increased significantly (P﹤0.01) at the same time after push-pull maneuver, The most of GFAP-positive cells belonged to strong positive fat type. It is suggested that +10Gz/3min exposure may induce significant increase of GFAP expression in rat parietal cortex, hippocampus and cerebral ganglion. GFAP expression increased more significantly after push-pull maneuver than after +10Gz exposure.In conclusion, we investigated the effects of repeated high +Gz exposures and push-pull maneuver on GFAP expressions of astrocytes in rat brain by means of animal centrifuge and immunohistochemical staining. The study has elucidated following questions: repeated +10Gz/45s exposures may induce significant increase of GFAP expression in parietal cortex and hippocampus of rat; +10Gz/3min exposure may induce significant increase of GFAP expression in rat parietal cortex, hippocampus and cerebral ganglion. GFAP expression increased more significantly after push-pull maneuver than after +10Gz exposure. Our investigation offered important gist for further elucidation of the mechanism of brain injury induced by repeated high +Gz exposures and push-pull maneuver.