GLUL and Alzheimer disease: In the triple transgenic AD mouse model (3xTg-AD), astrocytic glutamine synthetase expression was found to be decreased in the hippocampus, suggesting a critical role of astrocytes in AD-related disruption of glutamate homeostasis, which may affect the efficiency of glutamatergic transmission, contributing to the cognitive deficits of the disease (Olabarria et al., 2011).