Learning-induced arg 3.1/arc mRNA expression in the mouse brain.
The effector immediate-early gene (IEG) arg 3.1, also called arc, encodes a protein interacting with the neuronal cytoskeleton. The selective localization of arg 3.1/arc mRNA in activated dendritic segments suggests that the arg 3.1/arc protein may be synthesized at activated post-synaptic sites and that arg 3.1/arc could participate in structural and functional modifications underlying cognitive processes like memory formation. To analyze whether learning itself is sufficient to trigger expression of arg 3.1/arc, we developed a one-trial learning paradigm in which mice learned to enter a dark compartment to escape from an aversively illuminated area. Arg 3.1/arc mRNA expression was analyzed by in situ hybridization in three groups of mice as follows: a control group with no access to the dark compartment, a learning group having access to the dark compartment for one trial, and a retrieval group having access to the dark compartment for two trials on consecutive days. All animals from the learning and retrieval groups escaped the illuminated area, and those tested 24 h later (retrieval group) showed a strongly reduced latency to enter the dark compartment, demonstrating the validity of our learning paradigm to induce long-term memory. Our results show that acquisition of a simple task results in a brain area-specific biphasic increase in arg 3.1/arc mRNA expression 15 min and 4.5 h post-training. This increase was detected specifically in the learning group but neither in the control nor in the retrieval groups. The pattern of arg 3.1/arc mRNA expression corresponds temporally to the two mRNA- and protein-synthesis-dependent periods of long-term memory formation. Our study provides the first unequivocal evidence that arg 3.1/arc expression is induced by a learning task and strongly suggests a role of arg 3.1/arc mRNA in the early and late cellular mechanisms underlying the stabilization of the memory trace.
Montag-Sallaz
Monique
M
Neurogenetics Research Group, Leibniz Institute for Neurobiology, D-39118 Magdeburg, Germany. sallaz@ifn-magdeburg.de
Montag
Dirk
D
D000818:Animals; D001921:Brain / Q000378:metabolism* / Q000502:physiology; D001931:Brain Mapping; D003598:Cytoskeletal Proteins / Q000378:metabolism* / Q000502:physiology; D005786:Gene Expression Regulation; D017403:In Situ Hybridization; D007858:Learning; D008297:Male; D008568:Memory; D051379:Mice; D008810:Mice, Inbred C57BL; D009419:Nerve Tissue Proteins / Q000378:metabolism* / Q000502:physiology; D009474:Neurons / Q000378:metabolism / Q000502:physiology; D012333:RNA, Messenger / Q000378:metabolism
D003598:Cytoskeletal Proteins; D009419:Nerve Tissue Proteins; D012333:RNA, Messenger; C092069:activity regulated cytoskeletal-associated protein