Experience-dependent expression of rat hippocampal Arc and Homer 1a after spatial learning on 8-arm and 12-arm radial...

The expression of Arc and Homer 1a (H1a) depends on neural activity. This study was designed to determine hippocampal Arc and H1a mRNA expression levels after spatial learning with differing behavioral task demands. Forty-four male rats were distributed into 11 groups of four. One group received no training or trial sessions. Of the ten remaining groups, three were tested on the 8-arm maze, three on the 12-arm maze, two on the 8-arm maze and then the 12-arm maze, and two on the 12-arm maze and then the 8-arm maze. Each animal was sacrificed 30 min after the last session of maze testing and its hippocampus was immediately dissected and stored at -80°C. The level of mRNA expression at different stages of maze learning was determined using real-time reverse-transcription polymerase chain reaction (qRT-PCR). Significantly elevated expression of both Arc and H1a was observed. The orchestrated expression levels of both genes were correlated with the behavioral task demand level and behavioral performance.