Circuit-Specific Alterations in Hippocampal Synaptophysin Immunoreactivity Predict Spatial Learning Impairment in Aged Rats

• DOI: 10.1523/jneurosci.20-17-06587.2000
• Publication Date: 2018-04-13T22:25:12Z
• Authors: Thressa D. Smith; Michelle M. Adams; Michela Gallagher; John H. Morrison; Peter R. Rapp
• Keywords: Synaptophysin; Entorhinal cortex

The present study examined the long-standing concept that changes in hippocampal circuitry contribute to age-related learning impairment. Individual differences spatial were documented young and aged Long-Evans rats by using a hippocampal-dependent version of Morris water maze. Postmortem analysis used confocal laser-scanning microscopy method quantify immunofluorescence staining for presynaptic vesicle glycoprotein, synaptophysin (SYN), principal relays circuitry. Comparisons based on chronological age alone failed reveal reliable difference intensity SYN any region was examined. In contrast, subjects with deficits displayed significant reductions immunoreactivity CA3 lacunosum-moleculare (LM) relative either controls or age-matched preserved learning. values latter groups indistinguishable. addition, individual capacity among correlated levels selectively three regions: outer middle portions dentate gyrus molecular layer CA3-LM. cross-sectional area labeling, comparison, not reliably affected relation cognitive status. These findings are first demonstrate circuit-specific pattern variability connectional organization hippocampus is coupled outcome normal aging. regional specificity these effects suggests decline fidelity input from entorhinal cortex may play critical role.