Evaluation of marble-burying behavior as a model of anxiety.

On individual placement in a cage with 20 evenly spaced glass marbles, female MF1 mice buried 7.8 +/- 0.2 marbles. Olfactory stimuli from experimenters hands and sex of mice had no influence on number buried, but most marbles were buried when they were evenly spaced. There was no habituation to these novel objects on serial testing or prehousing with marbles and, in a two-compartment box, mice did not avoid marbles, spending half their time on the marble side. In the pharmacological experiments, locomotor activity was measured separately to indicate the possibility of nonspecific effects. The anxiogenic agents yohimbine and ethyl-beta-carboline-3-carboxylate (beta-CCE) did not enhance burying, yohimbine decreased burying at doses also reducing locomotor activity. Diazepam effects depended on dose: 0.1 mg/kg increased burying, 0.25 mg/kg had no effect and 1.0-5.0 mg/kg reduced it. Diazepam increased locomotor activity from 0.1-2.5 mg/kg and had no effect at 5.0 mg/kg. Zimeldine, 10.0 mg/kg, reduced burying but not locomotor activity. Inhibition of marble burying may be a correlational model for detection of anxiolytics rather than an isomorphic model of anxiety.