INS and Alzheimer disease: STZ produces brain insulin resistance or impaired insulin receptor in the brain which leads to Aβ accumulation forming senile plaques and increased tau-phosphorylation forming neurofibrillary tangles by increasing the activity of GSK-3β that results in neuronal and synaptic dysfunction, memory impairment which further leads to AD like pathology (Shingo et al., 2012; Stöhr et al., 2013).