Phosphorylation of the tau protein sequence 199-205 in the hippocampal CA3 region of Syrian hamsters in adulthood and during aging.

Paired helical filaments formed by the abnormally phosphorylated microtubule-associated tau are a main sign of Alzheimer's disease and other neurodegenerative disorders. The hippocampal CA3 region, a brain region with a high degree of synaptic plasticity, is known to be strongly involved in tau hyperphosphorylation in several neurodegenerative diseases. In addition, reversible tau phosphorylation was observed during hibernation in European ground squirrels. The present study provides data on the tau phosphorylation status in the hippocampus of euthermic Syrian hamsters (Mesocricetus auratus), laboratory animals potentially prone to hibernation. Mossy fibers in the CA3 region of all investigated hamsters were immunostained using an antiserum detecting phospho-serine 199 of tau. A similar staining pattern was obtained with CP-13 detecting phospho-serine 202. In contrast, the monoclonal antibody AT8, recognizing both phosphorylated serine 202 and threonine 205, stained the CA3 region only in old hamsters. These findings implicate an additional link between aging, tau phosphorylation and synaptic plasticity. Furthermore, the presented data allow analyses whether tau phosphorylation is reversible in these facultative hibernators and versatile laboratory animal as it was recently shown for the hibernation cycle of European ground squirrels.