Differential alterations of neocortical GluN receptor subunits in patients with mixed subcortical ischemic vascular dementia and Alzheimer's disease.

BACKGROUND

Glutamatergic deficits are well-established neurochemical findings in Alzheimer's disease (AD) and are thought to underlie both cognitive and behavioral symptoms of the disease. However, it is unclear whether subcortical ischemic vascular dementia (SIVD) and mixed SIVD/AD (MixD) manifest similar changes in the glutamatergic system.

OBJECTIVE

To measure the immunoreactivities of NMDA receptor GluN1, GluN2A, and GluN2B subunits in SIVD and MixD.

METHODS

Postmortem neocortical tissues from a cohort of well-characterized, longitudinally followed-up patients with SIVD and MixD, together with age-matched controls, were processed for immunoblotting with GluN subunit-specific antibodies.

RESULTS

There was a significant reduction of GluN1 only in MixD, while significant increases of GluN2A and GluN2B were found only in SIVD. Furthermore, GluN1 loss and GluN2A/2B upregulation was associated respectively with higher Braak stages and lacunar infarct scores.

CONCLUSIONS

Our data suggest that the differential alterations of GluN subunits in SIVD and MixD may result from separate, interacting disease processes, and point to the potential utility of glutamatergic approaches for pharmacotherapy.