Objective To study the relationship between the expression ratio of induced nitric oxide synthase (iNOS) over glial fibrillary acidic protein (GFAP) and the time of injury after brain concussion in rat, in order to acquire a new visual angle for determining injury time of cerebral concussion. Methods Eighty-five healthy Sprague-Dawley rats were divided into three groups randomly: model group (n=25), experimental group (n=55), and control group (n=5). The rats in the model group were used to confirm the attack hight to make the model of brain concussion; according to the time of execution, rats in the experimental group were then subdivided into 11 groups with 5 rats in each subgroup, and their execution time was respectively hour 0.5, 1, 3, 6, 12, 24, 48, 96, 168, 240, and 336; the rats in the control group were executed after fed for 24 hours. After the model of cerebral concussion was established through freefalling dart method, hematoxylin-eosin staining and immunohistochemistry staining of iNOS and GFAP were conducted for the brain of the rats. All related experimental results were studied by using microscope with image analytical system and homologous statistics. Results The ratio of positive expression of iNOS over that of GFAP increased gradually during hour 0.5- 3 after injury in brain (from 5.03 to 10.47). At the same time, the positive expression of iNOS increased significantly (from 14.61% to 37.45%). However, the increase of the positive expression of GFAP was not obvious. Between hour 3 and 12, the ratio began to decline to 4.98, which was still at a high level, and during the same time period, the positive expressions of iNOS and GFAP also experienced the same change pattern. Later, the ratio began to decline between hour 12 and 336 after injury (from 4.98 to 0.95). All ratios at this time were lower than those between hour 0.5 and 12. The positive expression of iNOS and GFAP both increased to a climax before declining. Conclusions The ratio of positive expression of iNOS over GFAP and the respective change pattern of iNOS and GFAP can be used as the evidence of estimating the injury time of cerebral concussion. We can use the ratio of two or more markers to provide a new visual angle for concluding the concussion injury time.
Objective To study the relationship between the expression ratio of heat shock protein (HSP) 70 to C-fos in organs outside the brain after brain concussion and the time of injury in rats, in order to provide a new visual angle for determining injury time of brain concussion. Methods The model of brain concussion was established through free falling method. Then the rats were executed at 30 minutes, 1 hour, and 3, 6, 12, 24, 48, 96, 168, 240, 336 hours after injury. Immunohistochemistry staining of C-fos and HSP70 were used in the materials from the main organs including heart, liver, spleen, lung and kidney. All related experiment results were studied by using a microscope with image analytical system and homologous statistics. Results From 30 minutes to 6 hours after injury, the proportion of HSP70 immuno-positive cells increased slowly, while the proportion of C-fos immuno-positive cells increased rapidly, and the ratio of HSP70/C-fos positive cells was on the decline. From 6 to 12 hours after injury, the proportion of HSP70 immuno-positive cells rose continuously, while the proportion of C-fos immuno-positive cells started to decrease, and the HSP70/C-fos ratio showed a rising tendency. From 12 to 336 hours after injury, the proportion of HSP70 immuno-positive cells decreased slowly, while the proportion of C-fos immuno-positive cells decreased rapidly, and the HSP70/C-fos ratio was still on the rise. Conclusions The proportion of positive cells and ratio of the two markers in the main organs including heart, liver, spleen, lung and kidney are similar to those in the brain of rats after brain concussion. Observing the proportion of positive cells of the two markers together with their ratio in the main organs outside the brain may provide a reference for the determination of injury time after brain concussion.