Dynamic induction of the long pentraxin PTX3 in the CNS after limbic seizures: evidence for a protective role in seizure-induced neurodegeneration.

Pentraxin 3, a prototypic long pentraxin, is induced by proinflammatory signals in the brain. Inflammatory cytokines are rapidly induced in glia by epileptic activity. We show that pentraxin 3 immunoreactivity and mRNA are enhanced in the rat forebrain above undetectable control levels by limbic seizures with a dual pattern of induction. Within 6 h from seizure onset, pentraxin 3 immunoreactivity was increased in astrocytes. Eighteen to 48 h later, specific neuronal populations and leucocytes were strongly immunoreactive only in areas of neurodegeneration. This staining was abolished when neuronal cell loss, but not seizures, was prevented by blocking N-methyl-D-aspartate receptors. Pentraxin 3 -/- mice had a more widespread seizure-related neuronal damage in the forebrain than their wild-type littermates although both groups had similar epileptic activity. Our results provide evidence that pentraxin 3 is synthesized in brain after seizures and may exert a protective role in seizure-induced neurodegeneration.