NGF and Cognitive impairment: Rats early develop characteristic mild cognitive impairment, associated with neuronal sufferance29 and dysregulation in the metabolism of protein markers of neurodegeneration, as protein tau and nerve growth factor (NGF) molecular systems.27,28 Saline, MWCNTs 1 or a-MWCNTs 2 were intranasally delivered to healthy and diabetic rats for one or three consecutive days, and then the animals were euthanized.