A new model of diffuse brain injury in rats

Abstract

This report describes the development of an experimental head injury model capable of producing diffuse brain injury in the rodent. A total of 161 anesthetized adult rats were injured utilizing a simple weight-drop device consisting of a segmented brass weight free-falling through a Plexiglas guide tube. Skull fracture was prevented by cementing a small stainless-steel disc on the calvaria. Two groups of rats were tested: Group 1, consisting of 54 rats, to establish fracture threshold; and Group 2, consisting of 107 animals, to determine the primary cause of death at severe injury levels. Data from Group 1 animals showed that a 450-gm weight falling from a 2-m height (0.9 kg-m) resulted in a mortality rate of 44% with a low incidence (12.5%) of skull fracture. Impact was followed by apnea, convulsions, and moderate hypertension. The surviving rats developed decortication flexion deformity of the forelimbs, with behavioral depression and loss of muscle tone. Data from Group 2 animals suggested that the cause of death was due to central respiratory depression; the mortality rate decreased markedly in animals mechanically ventilated during the impact. Analysis of mathematical models showed that this mass-height combination resulted in a brain acceleration of 900 G and a brain compression gradient of 0.28 mm. It is concluded that this simple model is capable of producing a graded brain injury in the rodent without a massive hypertensive surge or excessive brain-stem damage.

Severity of experimental traumatic brain injury modulates changes in concentrations of cerebral free amino acids

“…injection. Since we were interested in a type of trauma producing a diffuse axonal injury, graded TBI (mTBI or sTBI) was induced according to the weight drop impact acceleration model characterized by causing diffuse axonal damage 37. After anaesthesia, a metal disk was fixed onto the central portion of the skull, between the coronal and lambdoid sutures, to prevent skull fracture and to homogenously distribute the force acting at the time of impact.…”

“…After anaesthesia, a metal disk was fixed onto the central portion of the skull, between the coronal and lambdoid sutures, to prevent skull fracture and to homogenously distribute the force acting at the time of impact. Mild or severe TBI were induced by dropping a cumulative weight of 450 g from 1 or 2 m height and knowing to cause, respectively, a mTBI or a sTBI either histopathologically or biochemically 34, 35, 36, 37, 38. At 6, 12, 24, 48 and 120 hrs from injury, rats were again anaesthetized ( n = 6 for each time‐point in both groups of injured animals) and then immediately killed.…”

Histopathological changes in the choroid plexus after traumatic brain injury in the rats: a histologic and immunohistochemical study

“…A rectal probe was inserted, and the animals were positioned on a heating pad that maintained the body temperature at 37 °C. The widely used diffuse brain injury model described by Marmarou et al was used (17). Briefly, a trauma device which works by dropping a constant weight from a specific height through a tube was used.…”

Detecting diffuse axonal injury in rat brainstems by diffusion tensor imaging and AQP4 expression

“…Rats were anesthetized with an intraperitoneal chloral hydrate injection (0.3 ml/kg i.p.). A total of 40 anesthetized adult rats were injured using the impact-acceleration model of Marmarou [1]. To deliver DAI, animals were placed on a 20 cm thick sponge bed in a prone position.…”

“…In a series of experiments on human test subjects proved that the major component contributing to traumatic brain swelling and increased intracranial pressure (ICP) was not vascular engorgement, but rather a decreased CBF [1]. Thus, swelling and increased ICP relates to diffuse cytotoxic brain edema.…”