A behavioral and neuroanatomical assessment of an inbred substrain of 129 mice with behavioral comparisons to C57BL/6J mice

The inbred 129 substrains have been characterized as poor learners that dis play hypoplasia of the corpus callosum. However, they are used extensively as a sourer of embryonic stem (ES) cells for creating mice carrying altered copies of a targeted gene ('knockout mice'). The present research investig ated callosal agenesis and behavior in the 129/SvEvTac substrain and compar ed their behavior to that of C57BL/6J mice. in addition, the degree to whic h callosal agenesis affected behavior was assessed. Nearly 80% of 129/SvEvT ac mice in the current sample exhibited callosal hypoplasia, although this was not subsequently found to be associated with any measure of cognition. They learned the Morris maze and a non-spatial pattern discrimination task, though at a level inferior to C57BL/6J mice. They were unable to learn shu ttlebox avoidance or the Lashley III maze. The only measure on which they p erformed better than C57BL/6J mice was a simple water escape task. Thus, 12 9/SvEvTac mice, in addition to displaying aberrant neuroanatomy, perform po orly on many behavioral tasks, resulting in potential interpretational diff iculties. (C) 1999 Elsevier Science B.V. All rights reserved.