Enriched environmental conditions reverse age-dependent gliosis and losses of neurofilaments and extracellular matrix components but do not alter lipofuscin accumulation in the hindlimb area of the aging rat brain.

We provide a description of a correlation of lipofuscin accumulation and expression of glial fibrillary acidic protein in the cerebral cortex of aged rats. Glial fibrillary acidic protein showed a complementary distribution pattern to perineuronal nets, visualized with Wisteria floribunda agglutinin. With progressing age (12-36 months), a strong increase of lipofuscin and gliosis occurred in functionally characterized cortical areas, whereas a concomitant, area-specific loss of perineuronal nets was found in the cortical somatosensory representation of the hindlimbs. In contrast to lipofuscin accumulation and increased gliosis, the loss of perineuronal nets and the reduction of non-phosphorylated neurofilament H were in part reduced or prevented by housing the animals under enriched environmental conditions between 33 and 36 months of age. Especially the reduction of astrocytosis by 20% which coincided with a reduction in the loss of extracellular matrix components involved in forming the glia-neuron-interface demonstrates, that the aging cortex retains its potential for functional plasticity.