Few studies have compared the processing of endogenous human amyloid precursor protein (APP) in younger and older neurons. Here, we characterized LUHMES cells as a human model to study Alzheimer’s disease-related processes during neuronal maturation and aging. Differentiated LUHMES expressed and spontaneously processed APP via the secretase pathways, and they secreted amyloid (beta) (A(beta) ) peptide. This was inhibited by cholesterol depletion or secretase inhibition, but not by block of tau phosphorylation. In vitro aged cells increased A (beta) secretion without upregulation of APP or secretases. We identified the medium constituent glial cell line-derived neurotrophic factor (GDNF) as responsible for this effect. GDNF-triggered A (beta) release was associated with rapid upregulation of the GDNF coreceptor "rearranged during transfection" (RET). Other direct (neurturin) or indirect (nerve growth factor) RET activators also increased A(beta) , whereas different neurotrophins were ineffective. Downstream of RET, we found activation of protein kinase B (AKT) to be involved. Accordingly, inhibitors of the AKT regulator phosphatidylinositol-3-kinase completely blocked GDNF-triggered AKT phosphorylation and A (beta) increase. This suggests that RET signaling affects A(beta) release from aging neurons.