The experiments were performed following the recommendations of the Declarations of Helsinki and Tokyo and to the Guidelines for the Use of Experimental Animals of the European Community. The experiments were approved by the Animal Care Committee of Ben-Gurion University of the Negev.
1. Preparing rats for the experimental procedure
NOTE: Select adult male Sprague-Dawley rats weighing 300-350 g.
2. Induction of diffuse axonal injury
NOTE: The device consists of the following components: 1) transparent plastic cylinder, 2) iron weight (1308 g), 3) rotation mechanism consisting of a cylindrical tube, two bearings upon which the axis rotate and a head fixation (for ear pins); 4) horizontal platform on which are fixed two bearings.
3. Measurement of rotational Kinematics/Biomechanical parameters.
4. Evaluation of Neurological Severity Score after 48 hours
NOTE: Neurological deficits were assessed and graded using a Neurological Severity Score, as previously described17,18,19. Alterations in motor function and behavior are assessed by a point-system such that a maximum score of 24 represents severe neurological dysfunction. A score of 0 indicates intact neurological status. The following behavioral functions are assessed.
5. Brain collection for histological examination after 48 hours
6. Immunochemical staining and examination
Table 1 illustrates the protocol timeline. The mortality rate in this model of DAI was 0%. A Mann-Whitney test indicated that neurological deficit was significantly greater for the 15 DAI rats compared to the 15 sham rats at 48 hours following intervention (Mdn = 1 vs. 0), U = 22.5, p < 0.001, r = 0.78 (see Table 2). The data are measured in counts and are presented as median and 25–75 percentile range.
Representative photomicrographs of thalamic sections of brain tissue are shown in Figure 1. Photomicrographs revealed axonal and neuronal βAPP immunoreactivities following isolated DAI in rats 48 hours post injury compared to the control group (67.46 ± 30 vs. 0 ± 0), U = 0, p < 1.1E-06, r = 0.92. The data are measured as counts and presented as mean ± SD.
Groups | Time | Procedures |
DAI (15 rats) | 0 h | Induction Diffuse Axonal Injury |
Sham (15 rats) | 48 h | Neurological Severity Score Assessment, |
DAI (15 rats) | Immunochemical staining of BAPP. |
Table 1: Demonstration of the protocol timeline. The various groups of rats at different times are shown: DAI = Diffuse axonal brain injury at the beginning of the experiment; At 48 hours, a Neurological Severity Score was determined and immunochemical staining of βAPP was performed in both groups.
NSS values of the various groups at 48 hours | ||
Animal Group | N | NSS 48 hours after DAI |
Sham | 15 | 0 (0-0) |
DAI | 15 | 1 (1-1)* |
Table 2: Neurological severity score. Neurological deficit 48 hours following DAI for 2 study groups. A Mann-Whitney test indicated that neurological deficit was significantly greater for the 15 DAI rats compared to the 15 sham rats at 48 hours following intervention (Mdn = 1 vs. 0), U = 22.5, p < 0.001, r = 0.78. The data are measured in counts and are presented as median and 25–75 percentile range.
Figure 1: Immunochemical examination. Representative photomicrographs of thalamic sections of brain tissue revealed axonal and neuronal immunoreactivities following isolated DAI in rats (B) 48 hours post injury compared to the control group (A). βAPP immunoreactivity was detected in the region of interest in all 15 DAI rats, and not at all in any of the sham-operated rats. Mann-Whitney test indicated that number of βAPP -positive axons was significantly greater for 15 DAI rats than for sham-injured animals at 48h following DAI (67.46 ± 30 vs. 0 ± 0), U = 0, p < 1.1E-06, r = 0.92. Images are at the original magnification * 200. The data are measured as counts and presented as mean ± SD. Please click here to view a larger version of this figure.
0.01 M sodium citrate | SIGMA – ALDRICH | ||
2.5% normal horse serum | SIGMA – ALDRICH | H0146 | Liquid |
4 % buffered formaldehyde solution | |||
Anti-Amyloid Precursor Protein, C – terminal antibodyproduced in rabbit | SIGMA – ALDRICH | Lot 056M4867V | |
biotinylated secondary antibody | Vector | BA-1000-1.5 | 10 mM sodium phosphate, pH 7.8, 0.15 M NaCl, 0.08% sodium azide, 3 mg/ml bovine serum albumin |
bone-cutting forceps | |||
DAB Peroxidase (HRP) Substrate Kit (with Nickel), 3,3’-diaminobenzidine | vector laboratory | ||
embedding cassettes | |||
ethanol 99.9 % | ROMICAL | Flammable Liquid | |
guillotine | |||
Hematoxylin | SIGMA – ALDRICH | H3136-25G | |
Hydrogen peroxide solution | Millipore | 88597-100ML-F | |
Isofluran, USP 100% | Piramamal Critical Care, Inc | ||
Olympus BX 40 microscope | Olympus | ||
paraffine | paraplast plus leica biosystem | Tissue embedding medium | |
phosphate-buffered saline (PBS) | SIGMA – ALDRICH | P5368-10PAK | Contents of one pouch, when dissolved in one liter of distilled or deionized water, will yield 0.01 M phosphate buffered saline (NaCl 0.138 M; KCl – 0.0027 M); pH 7.4, at 25 °C. |
Streptavidin HRP | ABCAM | ab64269 | Streptavidin-HRP for use with biotinylated secondary antibodies during IHC / immunohistochemistry. |
xylene |
Traumatic brain injury (TBI) is a major cause of death and disability. Diffuse axonal injury (DAI) is the predominant mechanism of injury in a large percentage of TBI patients requiring hospitalization. DAI involves widespread axonal damage from shaking, rotation or blast injury, leading to rapid axonal stretch injury and secondary axonal changes that are associated with a long-lasting impact on functional recovery. Historically, experimental models of DAI without focal injury have been difficult to design. Here we validate a simple, reproducible and reliable rodent model of DAI that causes widespread white matter damage without skull fractures or contusions.
Traumatic brain injury (TBI) is a major cause of death and disability. Diffuse axonal injury (DAI) is the predominant mechanism of injury in a large percentage of TBI patients requiring hospitalization. DAI involves widespread axonal damage from shaking, rotation or blast injury, leading to rapid axonal stretch injury and secondary axonal changes that are associated with a long-lasting impact on functional recovery. Historically, experimental models of DAI without focal injury have been difficult to design. Here we validate a simple, reproducible and reliable rodent model of DAI that causes widespread white matter damage without skull fractures or contusions.
Traumatic brain injury (TBI) is a major cause of death and disability. Diffuse axonal injury (DAI) is the predominant mechanism of injury in a large percentage of TBI patients requiring hospitalization. DAI involves widespread axonal damage from shaking, rotation or blast injury, leading to rapid axonal stretch injury and secondary axonal changes that are associated with a long-lasting impact on functional recovery. Historically, experimental models of DAI without focal injury have been difficult to design. Here we validate a simple, reproducible and reliable rodent model of DAI that causes widespread white matter damage without skull fractures or contusions.