Cyclooxygenase-2 in the hippocampus is up-regulated in Alzheimer's disease but not in variant Alzheimer's disease with cotton wool plaques in humans.

We examined neuronal expression of cyclooxygenase-2, a pro-inflammatory protein, and neuron densities in the CA1-4 of the hippocampus in three cases of Alzheimer's disease with cotton wool plaques (CWP-AD), 17 cases of typical Alzheimer's disease without CWPs (tAD), and 26 normal controls. Cyclooxygenase-2 expression was significantly increased in all of the CA1-4 in tAD, but not in any subdivision in CWP-AD, compared with controls. Cyclooxygenase-2 expression in tAD was also significantly up-regulated compared with that in CWP-AD in all subdivisions. Furthermore, neuron density in the hippocampus was not significantly reduced in CWP-AD cases compared with controls despite remarkable intra- and extraneuronal Abeta deposition. These findings suggest that unknown factors besides Abeta deposition are necessary for the cyclooxygenase-2 up-regulation and neurodegeneration in Alzheimer's disease.