The influence of acute and chronic alcohol treatment on brain edema, cerebral infarct volume and neurological outcome following experimental head trauma in rats.

Abstract

The aim of this study was to determine the influence of acute and chronic ethanol treatment on neurological outcome following head trauma in rats. Eight-two Sprague-Dawley rats were divided into 10 groups. Four groups received sham head trauma (surgical incision of the scalp but no trauma) and were treated with (A) nothing, (B) chronic ethanol (6% ethanol in drinking water for 40 days), (C) acute ethanol 1.5 g/kg, intraperitoneally (IP) and (D) acute ethanol 3 g/kg IP. Four groups (E-H) received the same treatment; in addition, head trauma was delivered using a weight-drop device to the left cranium (2 h after ethanol treatment in the acute ethanol groups). To assess the influence of acute plus chronic alcohol and whether the glutamate antagonist ketamine can modify the neurologic outcome following head trauma, two additional head trauma groups were studied: group I received both acute and chronic ethanol treatment and group J received acute ethanol (1.5 g/kg) IP plus ketamine (180 mg/kg). Neurologic assessment was performed at 1, 2, 4, 8, 10, and 24 hours after head trauma or sham trauma in all animals who survived the treatment (omitted in group J animals while still under the anesthetic influence of ketamine). At the end of 24 hours, or at the time of death, the animals were decapitated. Specific gravity was determined from brain tissues adjacent to the injury and the contralateral hemispheres and the volume of hemorrhagic necrosis was quantified. None of the rats in the sham trauma groups died or had neurologic deficits. Of the head trauma groups, the mortality in animals that received 3 g/kg of ethanol and the animals that received acute plus chronic ethanol treatment was 100% before the end of 24 hours. Fifty percent of the animals receiving low-dose acute ethanol treatment (1.5 g/kg) died before 24 hours. In contrast, the mortality in the other groups was only 30% (p < 0.05). The neurologic severity score was significantly higher (greater neurological deficit) in the surviving animals that received acute ethanol treatment at 10 and 24 hours than in rats receiving no ethanol or chronic ethanol treatment. Specific gravity was also lower in the acute ethanol-treated groups compared with no ethanol, chronic ethanol, and acute ethanol plus ketamine groups (p < 0.03). Based on these observations, we conclude that in this rat head trauma model acute ethanol treatment increases mortality, neurological deficit, hemorrhagic necrosis volume, and brain edema. On the other hand, chronic ethanol treatment has no apparent effect and ketamine treatment does not counteract the effect of acute ethanol treatment.