Figure 1.
ISF Aβ obtained by microdialysis from behaving 3-month-old J20 hAPP tg mice. a, Rapid decline of ISF Aβ (t1/2, ∼2 h) upon acute γ-secretase inhibition in vivo in 3-month-old tg (vs wt littermate) mice. ISF sampled hourly at 1 μl/min; Compound E injected at time = 0 h. b, c, ISF collected at 0.2 μl/min were immunoprecipitated with AW8 Aβ antiserum and subjected to two types of SDS-PAGE. b, Conventional SDS-PAGE separates ISF Aβ into a ∼4 kDa [monomers (M)] and a ∼5 kDa Aβ-immunoreactive (lane 3) species. No dimers (D) were detected in ISF, but can be seen in the TBS-extract of a 24-month-old tg mouse (lane 2) or synthetic (synth.) Aβ (lane 1). WB was performed with 6E10 plus 4G8. c, Bicine/urea SDS-PAGE resolved ISF Aβ into three bands comigrating with synthetic Aβ1–38, Aβ1–40, and Aβ1–42, plus a fourth faint band corresponding to Aβ1–39. WB was performed with 6E10. d, Using 6E10 Aβ triplex ELISA, we quantified Aβx–38, Aβx–40, and Aβx–42 in ISF (mean ± SEM: 635 ± 70, 1937 ± 311, and 592 ± 58 pg/ml, respectively; n = 7 mice). e, Interpolated zero-flow method (mean ± SEM; n = 3–4 mice).