GDNF and Alzheimer disease: In addition, it was reported that rearranged during transfection (RET) tyrosine kinase, which acts as a co-receptor of GDNF alongside GFRa1, was decreased in hippocampal neurons in a chronic cerebral hypoperfusion model of dementia [90]; moreover, overexpression of RET in AD neurons was related to neuronal survival [61,91].