Role of amyloid beta (25-35) neurotoxicity in the ferroptosis and necroptosis as modalities of regulated cell death in Alzheimer's disease

Neuronal cell death as a prominent pathological feature contributes to cognitive decline and memory loss in Alzheimer's disease. We investigated the role of two forms of cell death pathways, ferroptosis and necroptosis, and their interactions following entorhinal cortex (EC) amyloidopathy. The A beta 25-35 was bilaterally injected into the rat's EC, and Morris Water Maze was applied to determine spatial performance one week after A beta injection. For evaluation of ferroptosis and necroptosis involvement in A beta induced pathology, ferroptosis inhibitor, Fer-rostatin (Fer-1), and necroptosis inhibitor, Necrostatin (Nec-1), were injected into the EC during training days of behavioral test. Our behavioral and histological assessment showed spatial learning and memory impairment, along with neuropathology changes such as cell survival and intracellular A beta deposits in response to EC amy-loidopathy, which were ameliorated by treatment with Fer-1 or Nec-1. The expression of ferroptosis key factors GPX4 and SLC7A11 were decreased and the level of TfR was increased following A beta toxicity. Also, Necroptosis pathway related factors RIP1, RIP3, and MLKL were modulated by A beta neurotoxicity. However, application of Fer-1 or Nec-1 could inhibit the hippocampal ferroptosis and necroptosis pathways due to EC amyloidopathy. Our data also demonstrated that A beta-induced necroptosis suppressed by Fer-1, although Nec-1 had no effect on fer-roptosis, indicating that ferroptosis pathway is upstream of necroptosis process in the A beta neurotoxicity. More-over, A beta induced hippocampal mGLUR5 overexpression and reduced level of STIM1/2 recovered by Fer-1 or Nec-1. According to our findings ferroptosis and necroptosis pathways are involved in A beta neurotoxicity through modulation of mGLUR5 and STIM1/2 signaling.