Anxiety and sensitivity to ethanol and pentobarbital in alcohol withdrawal seizure-prone and withdrawal seizure-resistant mice

BACKGROUND: Withdrawal Seizure-Prone (WSP) and Withdrawal Seizure-Resistant (WSR) mice were selectively bred for high and low handling-induced convulsions, respectively, after chronic ethanol treatment. Withdrawal severity is one factor that may contribute to the development of alcoholism and/or substance abuse, and anxiety is another. We sought to explore whether these factors are genetically related. METHODS: WSP and WSR mice of two replicate pairs of selected lines were tested for anxiety-related behaviors on the canopy stretched-attend-posture apparatus 20 min after intraperitoneal injection of ethanol (2 g/kg, 20% v/v), pentobarbital (20 mg/kg), or an equivalent volume of saline. Dependent measures of anxiety included number of stretched attend postures (SAP) and time spent in the exposed area of the apparatus. Number of line crossings, which measures overall activity, was also scored. RESULTS: WSP mice given saline exhibited more SAP than WSR mice given saline, which indicated greater baseline anxiety. Ethanol and pentobarbital both reduced SAP and increased time spent in the exposed area of the apparatus, which indicated that both drugs exerted an anxiolytic effect. Despite baseline differences in SAP between selected lines, both anxiolytic drugs reduced SAP to similar levels in WSP and WSR mice. CONCLUSIONS: These results support the hypothesis that WSP mice are more sensitive than WSR mice to the anxiety-reducing effects of ethanol and pentobarbital. Some genes that influence this difference are likely to be the same as those that influence ethanol withdrawal severity. Thus, higher basal anxiety and greater genetic sensitivity to anxiolytic drug effects may relate to a greater genetic predisposition to the development of severe alcohol withdrawal signs.