Calretinin is an EF-hand calcium-binding protein involved in calcium signaling . Calretinin is expressed in hilar mossy cells and in widely distributed subsets of GABAergic interneurons in the normal mouse hippocampus . Calretinin maintains appropriate calcium ion concentration in cells and participates in the modulation of neuronal activity and synaptic plasticity . Knockout mice lacking calretinin show no alteration in basal synaptic transmission but impaired LTP in the dentate gyrus . These findings indicate that the decreased expression of calretinin might be involved in diabetes-induced dementia.