Effects of binge ethanol administration on the behavioral outcome of rats after lateral fluid percussion brain injury

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% et hanol in 5% glucose solution (3 g ethanol/kg; binge ethanol group), or 5% g lucose solution (vehicle group), twice on Thursday and Friday of 3 consecut ive weeks. Then rats from both groups were subjected to either lateral FP b rain injury of moderate severity (1.8 atm) or to sham operation. Postinjury behavioral measurements revealed that brain injury caused significant spat ial learning disability in both groups. There were no significant differenc es in mean search latencies in the sham animals between the vehicle and bin ge 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 tr ial blocks 2 and 4. There were no significant differences in the target vis its (expressed as mean zone difference [MZD]) during the probe trial betwee n the injured animals of binge ethanol and vehicle groups. However, there w as only a minor trend towards worsened MZD score in the binge-injured anima ls. Histologic analysis of injured animals from both injured ethanol and ve hicle groups revealed similar extents of ipsilateral cortical and observabl e hippocampal damage. These results suggest that 4 weeks of binge ethanol t reatment followed by ethanol intoxication at the time of injury worsens som e aspects of the spatial learning ability of rats. This worsening is probab ly caused by subtle, undetectable morphologic damage by binge ethanol admin istration.