Effect of Brain Cooling on Brain Ischemia and Damage Markers After Fluid Percussion Brain Injury in Rats

Abstract

Although systemic cooling had recently been reported as effective in improving the neurological outcome after traumatic brain injury, several problems are associated with whole-body cooling. The present study was conducted to test the effectiveness of brain cooling without interference with the core temperature in rats after fluid percussion traumatic brain injury (TBI). Brain dialysates ischemia (e.g., glutamate and lactate-to-pyruvate ratio) and injury (e.g., glycerol) markers before and after TBI were measured in rats with mild brain cooling (33 degrees C) and in the sham control group. Brain cooling was accomplished by infusion of 5 mL cold saline via the external jugular vein under general anesthesia. The weight loss was determined by the difference between the first and third day of body weight after TBI. The maximum grip angle in an inclined plane was measured to determine motor performance, whereas the percentage of maximal possible effect was used to measure blockade of proprioception. The triphenyltetrazolium chloride staining procedures were used for cerebral infarction assay. As compared with those of the sham-operated controls, the animals with TBI had higher values of extracellular levels of glutamate, lactate-to-pyruvate ratio, and glycerol in brain and intracranial pressure, but lower values of cerebral perfusion pressure. Brain cooling adopted immediately after TBI significantly attenuated the TBI-induced increased cerebral ischemia and injury markers, intracranial hypertension, and cerebral hypoperfusion. In addition, the TBI-induced cerebral infarction, motor and proprioception deficits, and body weight loss evaluated 3 days after TBI were significantly attenuated by brain cooling. We successfully demonstrate that brain cooling causes attenuation of TBI in rats by reducing cerebral ischemia and injury resulting from intracranial hypertension and cerebral hypoperfusion. Because jugular venipuncture is an easy procedure frequently used in the emergency department, for preservation of brain function, jugular infusion of cold saline may be useful in resuscitation for trauma patients.

Induced Normothermia Attenuates Cerebral Metabolic Distress in Patients With Aneurysmal Subarachnoid Hemorrhage and Refractory Fever

“…7 In brain-injured patients, however, it has not been clearly demonstrated that normothermia attenuates brain damage, and the exact mechanisms by which this may occur are only beginning to be elucidated. Although treatment of fever is routine in neurocritical care, proof of principle and clinical benefit have yet to be demonstrated.…”

An inclined plane system with microcontroller to determine limb motor function of laboratory animals

“…of 8 rats per group. cerebral infarct and motor dysfunction were found to be associated with both an increase in intracranial pressure and a decrease in cerebral perfusion pressure during traumatic brain injury (Chio et al, 2007). The decrease in cerebral perfusion pressure (=mean arterial pressure − intracranial pressure) is due to an increase in intracranial pressure because an appropriate level of mean arterial pressure is maintained after traumatic brain injury.…”

Defeating Normal Thermoregulatory Defenses

“…There is in vitro 2 and overwhelming animal 4 evidence that mild hypothermia provides substantial protection against tissue ischemia. Although the amount of protection varies with the model, several degrees of hypothermia typically provide factor-of-three benefits.…”

“…The first is in asphyxiated neonates. 4,5 It is easy to cool infants-in fact, the difficulty is usually preventing hypothermia. Mild hypothermia is thus rapidly being adapted as the therapeutic choice for asphyxiated neonates.…”