Inhibition of ACE Retards Tau Hyperphosphorylation and Signs of Neuronal Degeneration in Aged Rats Subjected to Chronic Mild Stress

Figure 1

Chronic unpredictable mild stress induced upregulation of hippocampal Ace protein and gene expression. (a) Immunohistological localization of Ace in a brain vessel of a stressed rat. Nuclei were stained with hematoxylin (HE); bar: 20 μm. (b) Immunofluorescence localization of Ace (red) and the pericyte marker Ng2 (green) in a brain vessel of a stressed rat. Ace was detected with affinity-purified rabbit anti-Ace antibodies followed by F(ab)₂ fragments of Alexa Fluor 546-labeled (red) secondary antibodies, and Ng2 was detected with affinity-purified murine anti-NG2 antibody followed by F(ab)₂ fragments of Alexa Fluor 488-labeled (green) secondary antibodies. Nuclei were stained with DAPI (bar: 20 μm). (c) Immunohistological localization of Ace in hippocampal CA3 neurons of a stressed rat (left) relative to a nonstressed control (right). Nuclei were stained with hematoxylin (HE); bar: 20 μm. Histological experiments are representative of 4 rats/group (a–c). (d) Hippocampal Ace gene expression was determined by qRT-PCR and is presented as the ratio of Ace/Gapdh expression (±s.d.; ; ). (e) Immunoblot detection of the hippocampal Ace protein with anti-Ace antibodies in stressed rats relative to nonstressed controls (/group). (f) Hippocampal Ace activity of stressed rats relative to nonstressed controls (i.e., 100%; ±s.d., ; ). (g) The hippocampal angiotensin II content was determined by immunoblot in stressed rats relative to nonstressed controls (upper panel). The lower panel shows a control immunoblot, which detects Gnb (/group).

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