COMPUTERIZED MEASUREMENT OF MK-801-ELICITED POPPING AND HYPERACTIVITYIN MICE

MK-801, a high-affinity phencyclidine (PCP) analogue, is a non-competi tive antagonist of the N-methyl-D-aspartate (NMDA) subclass of glutama te receptor that elicits hyperactivity, stereotypic behaviors, and ''p opping,'' an explosive episodic jumping behavior, in mice. The schizop hreniform psychosis precipitated by PCP in humans has stimulated inter est in studying MK-801-elicited mouse behaviors for their potential de velopment as animal models of idiopathic psychosis. We describe a comp uterized method for measuring popping and hyperactivity elicited by MK -801 in mice, based on vertical displacements of a platform. This comp uterized procedure allows for the automatic measurement of discrete '' pops'' per individual episode of popping behavior, the force of each o ne of the explosive jumps, and the duration of discrete episodes of po pping; these latter measures could not be easily ascertained by visual inspection alone. Moreover, the computerized measurements facilitate quantitative evaluation of the effects of pharmacological manipulation s on MK-801-elicited popping, For example, the antipsychotic haloperid ol was shown to reduce significantly both MK-801-induced popping and h yperactivity. Ideally, MK-801-elicited mouse popping and hyperactivity will serve as a useful preclinical screening paradigm for potential a ntipsychotic medications. Additionally, it is hoped that the use of th is automated system will contribute to a greater understanding of the mechanisms of MK-801-induced popping and hyperactivity.