Title:Glutamate Receptors in Human Caudate Nucleus in Normal Aging and Alzheimer’s Disease
Volume: 10
Issue: 5
Author(s): Konstantinos I. Tsamis, Dimitrios G. Mytilinaios, Samuel N. Njau and Stavros J. Baloyannis
Affiliation:
Keywords:
Dementia, GluR2, mGluR5, neostriatum, neurotransmission, NMDAR1.
Abstract: Neostriatum is one of the brain areas that are not primarily affected in Alzheimer’s disease, according to classic
regard of the disease. However, recent data emphasize the involvement of neostriatum, especially the head of the caudate
nucleus, in the emergence of characteristic symptoms of the disease. Glutamatergic neurotransmission is a key component
of striatal pathways. The present study is focused on glutamate receptors of striatal neurons on human caudate nucleus in
normal aging and Alzheimer’s disease. Immunohistochemical studies were carried out for N-methyl-D-aspartate receptor
subunit 1 (NMDAR1), α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor subunit 2 (GluR2) and
metabotropic glutamate receptor 5 (mGluR5). Ionotropic receptors (NMDAR1 and GluR2) were found to be expressed by
82% - 93% of striatal neurons with no significant alterations in aging and Alzheimer’s disease. On the other hand, metabotropic
receptor mGluR5 was found to be expressed by just 40% of striatal neurons in young individuals, with significant
intensity variations among the neurons. This percent was increased in elderly individuals and Alzheimer’s disease patients
to 80% and 92% of striatal neurons, respectively. The up-regulation of mGluR5 both in normal aging and Alzheimer’s
disease is possibly associated with reorganization of neuronal connections, indicates the complexity of this receptor
function and renders quite unpredictable the intervention and treatment of dementia with mGluR5 inhibitors or
modulators.
