Aβ25–35 (Sigma, St Louis, MO, USA) was dissolved in physiological saline to a final concentration of 2.5 g/L, and incubated for one week at 37 °C to reach a state of aggregation. CNTF antibodies (ab190985) and GDNF antibodies (ab18956) were obtained from Abcam (Cambridge, England). BDNF (sc-546) was purchased from Santa Cruz Biotechnologies (Santa Cruz, CA, USA). TUNEL kits (In Situ Cell Death Detection Kit and POD) were purchased from Roche (Switzerland).