Experience-dependent gene expression in the rat hippocampus after spatial learning: a comparison of the immediate-early genes Arc, c-fos, and zif268.
Neuronal immediate-early gene (IEG) expression is regulated by synaptic activity and plays an important role in the neuroplastic mechanisms critical to memory consolidation. IEGs can be divided into two functional classes: (1) regulatory transcription factors (RTFs), which can broadly influence cell function depending on the "downstream" genes they regulate, and (2) "effector" proteins, which may directly modulate specific cellular functions. The objective of the current study was to determine whether the expression of an effector IEG (Arc) was similar to, or different from, that of two well characterized RTF IEGs (c-fos and zif268) after learning. IEG RNA levels from rats trained in spatial and nonspatial water tasks were determined using RNase protection assays and in situ hybridization. Overall, the regulation of the three IEGs was similar in the hippocampus and the entorhinal and primary visual cortices. Consequently, IEG RNA levels were positively correlated within a structure. By contrast, Arc and zif268 RNA levels were not correlated or only weakly correlated across structures, although c-fos RNA levels were moderately correlated across structures. Arc RNA expression differed from that of zif268 and c-fos in two regards: (1) hippocampal Arc RNA levels were correlated with learning of the hippocampal-dependent spatial, but not hippocampal-independent cued response, water task, and (2) Arc RNA levels in the hippocampus and entorhinal cortex increased after spatial reversal learning relative to an asymptotic performance group. Thus, although the expression of Arc, zif268, and c-fos exhibited many similarities, Arc was most responsive to differences in behavioral task demands.
Guzowski
J F
JF
Arizona Research Laboratories, Division of Neural Systems, Memory and Aging, University of Arizona, Tucson, Arizona 85724-5115, USA. john@nsma.arizona.edu
Setlow
B
B
Wagner
E K
EK
McGaugh
J L
JL
D000818:Animals; D003463:Cues; D003598:Cytoskeletal Proteins / Q000235:genetics / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D018891:Dentate Gyrus / Q000166:cytology / Q000378:metabolism; D051766:Early Growth Response Protein 1; D018728:Entorhinal Cortex / Q000378:metabolism; D015870:Gene Expression / Q000502:physiology*; D005786:Gene Expression Regulation; D017781:Genes, Immediate-Early; D006624:Hippocampus / Q000166:cytology / Q000378:metabolism*; D017874:Immediate-Early Proteins; D017404:In Situ Hybridization, Fluorescence; D007858:Learning / Q000502:physiology*; D008297:Male; D018782:Maze Learning / Q000502:physiology*; D008568:Memory / Q000502:physiology; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism*; D016760:Proto-Oncogene Proteins c-fos / Q000235:genetics / Q000378:metabolism*; D017966:Pyramidal Cells / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*
D003598:Cytoskeletal Proteins; D004268:DNA-Binding Proteins; D051766:Early Growth Response Protein 1; C486110:Egr1 protein, rat; D017874:Immediate-Early Proteins; D009419:Nerve Tissue Proteins; D016760:Proto-Oncogene Proteins c-fos; D012333:RNA, Messenger; D014157:Transcription Factors; C092069:activity regulated cytoskeletal-associated protein