As shown in our previous studies, progression of the signs of AD in OXYS rats is accompanied by downregulation of the Gsk3b gene's mRNA in the cortex and increased mRNA expression of genes Cdk5, Casp9, and Capn1; these changes may also be triggered by the toxic forms of amyloid-β from neurodegenerative processes [38]. Here, CDK5 is linked to Alzheimer disease.