Arc Expression in the Dentate Gyrus of F344 Rats Across the Sleep-Wake Cycle.

The Arc gene is rapidly expressed in the dentate gyrus of the hippocampus during learning and is essential for long-term memory formation. Although memory consolidation, which occurs predominantly during sleep, depends on Arc, previous studies have reported conflicting findings regarding whether Arc expression changes across the sleep-wake cycle. As an initial step toward addressing these discrepancies, we established a baseline comparison of Arc expression in the dentate gyrus of naïve Fischer (CDF) rats (n = 44) across four timepoints spanning sleep and wake periods. Arc⁺ cell density remained remarkably stable across all timepoints.