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This study examined the effects of 4 weeks of binge ethanol administration (BEAn) on the behavioral outcome in rats after lateral fluid percussion (FP) brain injury. Rats were intragastrically given 7.5 mL/kg of either 40% ethanol in 5% glucose solution (3 g ethanol/kg; binge ethanol group), or 5% glucose solution (vehicle group), twice on Thursday and Friday of 3 consecutive weeks. Then rats from both groups were subjected to either lateral FP brain injury of moderate severity (1.8 atm) or to sham operation. Postinjury behavioral measurements revealed that brain injury caused significant spatial learning disability in both groups. There were no significant differences in mean search latencies in the sham animals between the vehicle and binge ethanol groups. On the other hand, the mean search latency of the binge ethanol group was significantly higher than that of the vehicle group in trial blocks 2 and 4. There were no significant differences in the target visits (expressed as mean zone difference [MZD]) during the probe trial between the injured animals of binge ethanol and vehicle groups. However, there was only a minor trend towards worsened MZD score in the binge-injured animals. Histologic analysis of injured animals from both injured ethanol and vehicle groups revealed similar extents of ipsilateral cortical and observable hippocampal damage. These results suggest that 4 weeks of binge ethanol treatment followed by ethanol intoxication at the time of injury worsens some aspects of the spatial learning ability of rats. This worsening is probably caused by subtle, undetectable morphologic damage by binge ethanol administration.

This study examined the effects of 3 months of chronic ethanol administration (CEAn) on the behavioral outcome in rats after lateral fluid percussion (FP) brain injury. Rats were given either an ethanol liquid diet (ethanol diet groups) or a pair-fed isocaloric sucrose control diet (control diet groups) for 3 months. Then, rats from both diet groups were subjected to either lateral FP brain injury of moderate severity (1.8 atm) or to sham operation. Postinjury behavioral measurements revealed that brain injury caused significant spatial learning disability in both diet groups. There were no significant differences in spatial learning ability in the sham or brain-injured animals between the control and ethanol diets. However, a trend towards cognitive impairment in the sham animals and a trend towards reduced deficits in the brain-injured animals were observed in the ethanol diet group. Histologic analysis of injured animals from both diet groups revealed similar extents of ipsilateral cortical and hippocampal CA3 damage. These results, in general, suggest that 3 months of CEAn does not significantly alter the behavioral and morphologic outcome of experimental brain injury.

This study examined the effects of 6 weeks of chronic ethanol administration on the behavioral outcome in rats after lateral fluid percussion (FP) brain injury. Rats were given either an ethanol liquid diet (ethanol diet-groups) or a pair-fed isocaloric sucrose control diet (control diet groups) for 6 weeks. After 6 weeks, the ethanol diet was discontinued for the ethanol diet rats and they were then given the control sucrose diet for 2 days. During those 2 days, the rats were trained to perform a beam-walking task and subjected to either lateral FP brain injury of low to moderate severity (1.8 atm) or to sham operation. In both the control diet and the ethanol diet groups, lateral FP brain injury caused beam-walking impairment on days 1 and 2 and spatial learning disability on days 7 and 8 after brain injury. There were no significant differences in beam-walking performance and spatial learning disability between brain injured animals from the control and ethanol diet groups. However, a trend towards greater behavioral deficits was observed in brain injured animals in the ethanol diet group. Histologic analysis of both diet groups after behavioral assessment revealed comparable ipsilateral cortical damage and observable CA3 neuronal loss in the ipsilateral hippocampus. These results only suggest that chronic ethanol administration, longer than six weeks of administration, may worsen behavioral outcome following lateral FP brain injury. For more significant behavioral and/or morphological change to occur, we would suggest that the duration of chronic ethanol administration must be increased.

The effects of 6 weeks of chronic ethanol administration on the lateral fluid percussion (FP) brain injury-induced regional accumulation of lactate and on the levels of total high-energy phosphates were examined in rats. In both the chronic ethanol diet (ethanol diet) and pair-fed isocaloric sucrose control diet (control diet) groups, tissue concentrations of lactate were elevated in the cortices and hippocampi of both the ipsilateral and contralateral hemispheres at 5 min after brain injury. In both diet groups, concentrations of lactate were elevated only in the injured left cortex and the ipsilateral hippocampus at 20 min after FP brain injury. No significant differences were found in the levels of lactate in the cortices and hippocampi of sham animals and brain-injured animals between the ethanol and control diet groups at 5 min and 20 min after injury. In the ethanol and control diet groups, tissue concentrations of total high-energy phosphates (ATP + PCr) were not affected in the cortices and hippocampi at 5 min and 20 min after lateral FP brain injury. No significant differences were found in the levels of total high-energy phosphates in the cortices and hippocampi of the sham and brain-injured animals between the ethanol and control diet groups at 5 min and 20 min after injury. Histologic studies revealed a similar extent of damage in the cortex and in the CA3 region of the ipsilateral hippocampus in both diet groups at 14 days after lateral FP brain injury. These findings suggest that 6 weeks of chronic ethanol administration does not alter brain injury-induced accumulation of lactate, levels of total high energy phosphates, and extent of morphological damage.