Neurobehavioral studies, in transgenic F3/CONTACTIN (C57BL/6J ◊ CBA) mice, on cognitive and anxiety aspects during late-adolescential period

OBJECTIVE : Besides than in the control of developmental events, axonal adhe - sive glycoproteins may be also involved in func - tions requiring fine organization and connectivi - ty of the nervous tissue. We previously demon - strated morphological alterations and functional cerebellar deficits in transgenic mice (TAG/F3 mice) ectopically expressing the F3/Contactin axonal glycoprotein under the control of a se - lected regulatory region from the Transient Ax - onal Glycoprotein (TAG-1) gene. In the present study, the hippocampal function was explored by evaluating the ability of TAG/F3 mice to en - code spatial and non-spatial relationships be - tween discrete stimuli and to analyze an anxiety- related behavior. MATERIALS AND METHODS: To the first end, mice were placed in an "open-Field" containing five objects and, after three sessions of habitua - tion (S2-S4), their reactivity to objects displace - ment (S5-S4) and object substitution (S7-S6) was examined.To the second end, mice were placed in the "elevated zero maze", a standard test to ex - plore the anxiety-related behavior, in order to study, in transgenic mice, the effects of F3 misex - pression on emotional reactivity by measuring the avoidance of the unsheltered open sectors. RESULTS: Statistical evaluations of reactivity to object novelty, TAG-F3 mice showed a lower DO exploration with respect to wild-type mice and, regarding DOs,TAG/F3 mice interacted less than wild-type mice, showing an impaired spatial change response. Furthermore, the number of HDIPS in transgenicTAG/F3 mice resulted signif - icantly lower with respect to the controls (wild type). CONCLUSIONS: These results indicate that the coordinated expression of axonal adhesive glycoproteins may be relevant for the functional maturation of the hippocampus.