engleski

Expression of neuroplastin is increased in hippocampal tissue affected by Alzheimer's neurodegeneration

Neuroplastin, glycoprotein found in two splice isoforms (np65, np55), is a member of immunoglobulin superfamily including different cell adhesion molecules. Brain specific localization of np65 and its association with synaptic plasticity and long-term potentiation was found in rodent brain. Distribution of np65 in adult human brain has been described, however systematic data on its expression during developmental stages, maturation, aging and neurodegeneration are surprisingly lacking. Alzheimer’s disease (AD) is characterized by up-regulated expression of plasticity molecules, particularly in hippocampus and entorhinal cortex, reflecting activation of compensatory mechanisms and reorganization of remaining cellular structures. In this study, the expression of neuroplastin (np65) was analyzed in human hippocampal tissue affected by Alzheimer’s neurodegeneration. Paraffin-embedded sections of hippocampal tissue derived from 3 AD and 3 age- and gender-matched controls were analyzed by immunohistochemistry, using primary anti-neuroplastin antibody. Neuroplastin immunoreactivity pattern and intensity was additionally analyzed using ImageJ software. Results on distribution of neuroplastin immunoreactivity confirmed its extracellular localization in both control and AD hippocampal sections. The overall intensity of neuroplastin immunoreactivity was higher in AD than in control hippocampi, and was most notably expressed in neuronal population of dentate gyrus inner molecular layer ; also, patch-like immunoreactivity was observed in stratum pyramidale of subiculum. Interestingly, unexpected intracellular localisation/accumulation of neuroplastin was detected in AD hippocampi, mostly in subiculum, which may indicate altered posttranslational modification and trafficking of neuroplastin molecule. We suggest that neuroplastin may serve as additional plasticity marker, as its expression is increased in AD neurodegeneration due to described reorganization and plasticity reactivation.

Alzheimer's disease; hippocampus; neuroplastin

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