Effect of glucose administration on contusion volume after moderate cortical impact injury in rats

Previous studies had shown that pre- and postinjury glucose administration increased brain injury caused by a mild cortical impact injury only when th e traumatic injury was complicated by a secondary ischemic insult. The purp ose of this study was to examine the effect of pre- and postinjury glucose administration on a more severe cortical impact injury, where primary ische mia occurs at the site of the impact, Long Evans rats who were fasted overn ight and anesthetized with isoflurane were subjected to a 5-m/sec, 2.5-mm i mpact injury. The animals were randomly assigned one of the following treat ments: (1) 2.2 g/kg glucose in 4 mi of saline, 20 min prior to injury; (2) 2.0 g/kg glucose in 4 mi of saline, 20 min after injury; or (3) 4 mi of sal ine either 20 min before injury or 20 min after the injury, At 2 weeks, the animals were sacrificed and the brains were examined for contusion volume and for neuronal loss in CA1 and CA3 regions of the hippocampus. Contusion volume was increased from a median value of 23 mm(3) in the saline-infused animals to 34 mm(3) in the preimpact glucose infusion animals (p = 0.005), Postimpact glucose infusion had no effect on contusion volume, Neuron densi ty in CA1 and CA3 regions of the hippocampus was similar in all three treat ment groups. These studies support the hypothesis that glucose administrati on adversely affects experimental traumatic brain injury in those circumsta nces where the trauma is complicated by primary cerebral ischemia, such as around cortical contusions.