ROLE OF F3/CONTACTIN IN SYNAPTIC PLASTICITY AND MEMORY

F3/contactin is a cell-adhesion molecule belonging to the immunoglobulin superfamily, involved in building and maintaining synapses during brain development. Here we investigated the role of F3/contactin in hippocampal synaptic plasticity and memory. We used transgenic (Tg) mice in which F3/contactin expression is driven by TAG-1 gene regulatory sequences (TAG/F3 mice) undergoing an increased expression of F3/contactin in the forebrain in late development. We analyzed reference memory by using Morris Water Maze test and the following forms of plasticity: i) paired pulse facilitation (PPF), a short-term plasticity that is thought to reflect presynaptic mechanisms; ii) long-term potentiation (LTP), a pre- and post-synaptic long-term plasticity that is thought to underlie learning and memory. We found that young TAG/F3 animals (4-6 months) showed no difference either in behavioral performance or in electrophysiology when compared with wild type littermates. On the contrary, an improvement of LTP and reference memory was observed in aged TAG/F3 homozygous mice (12-15 months), PPF remaining unchanged. Our data suggest that F3/contactin improved hippocampal synaptic plasticity and memory in aged mice. This is consistent with previous findings showing that old animals present a decrease in hippocampal F3/contactin levels probably associated with cognitive impairment.