Loss of calretinin and parvalbumin positive interneurones in the hippocampal CA1 of aged Alzheimer's disease mice.

Neuronal degeneration associated with Alzheimer's disease (AD), is linked to impaired calcium homeostasis and to changes in calcium-binding proteins (CBPs). The AD-related modification of neuronal CBPs remains controversial. Here we analysed the presence and expression of calretinin (CR) and parvalbumin (PV) in the hippocampal CA1 neurones of 18 months old 3xTg-AD mice compared to non-Tg animals. We found a layer specific decrease in number of interneurones expressing CR and PV (by 33.7% and 52%, respectively). Expression of PV decreased (by 13.8%) in PV-positive neurones, whereas expression of CR did not change in CR positive cells. The loss of specific subpopulations of Ca2+-binding proteins expressing interneurones (CR and PV) together with the decrease of PV in the surviving cells may be linked to their vulnerability to AD pathology. Specific loss of inhibitory interneurones with age could contribute to overall increase in the network excitability associated with AD.