Reduction of Aβ accumulation in the Tg2576 animal model of Alzheimer's disease after oral administration of the phosphatidylinositol kinase inhibitor wortmannin

Abstract

The abnormal accumulation of the amyloid beta protein (Abeta) has been implicated as an early and critical event in the etiology and pathogenesis of Alzheimer's disease (AD). Compounds that reduce Abeta accumulation may therefore be useful therapeutically. In cell-based screens we detected a significant reduction in Abeta concentration after treatment with the phosphatidylinositol kinase inhibitors wortmannin and LY294002. To determine the effect of this class of compounds on in vivo Abeta accumulation, we administered wortmannin to the Tg2576 mouse model of AD. Oral administration of wortmannin over four months resulted in a significant, non-overlapping 40%-50% reduction in the number of senile plaques, one of the pathological hallmarks of AD. Sandwich ELISA analysis of formic acid extractable Abeta in the brain of treated animals indicates that both Abeta40 and the longer, more amyloidogenic form of the peptide, Abeta42, were significantly reduced. These data provide the first direct evidence that compounds identified by their ability to reduce Abeta concentration in vitro can reduce Abeta accumulation and deposition in the brain, thus establishing a basic paradigm for the identification and evaluation of additional compounds that lower Abeta accumulation.

Dynamics of β-Amyloid Reductions in Brain, Cerebrospinal Fluid, and Plasma of β-Amyloid Precursor Protein Transgenic Mice Treated with a γ-Secretase Inhibitor

“…Attempts to give continuous exposure using BMS-299897 in chow were also limited by significant apparent autoinduction (data not shown). Reductions in plaque formation in APP transgenic mice have been reported after various treatments, all of which required 1 to 6 months of treatment (Schenk et al, 1999;Lim et al, 2000;Cherny et al, 2001;Haugabook et al, 2001;Refolo et al, 2001;Carro et al, 2002;Jantzen et al, 2002;Permanne et al, 2002;Deane et al, 2003;Matsuoka et al, 2003;Yan et al, 2003). Two weeks of treatment with a nitric oxide-releasing nonsteroidal anti-inflammatory drug was not sufficient to reduce plaque load, although 5 months of treatment was effective (Jantzen et al, 2002).…”

Amyloid-β peptide levels in brain are inversely correlated with insulysin activity levels in vivo

“…The rIDE 4020 antibody was elicited by immunization with nickel agarose-purified recombinant rat insulysin with an N-terminal six-histidine tag, which was expressed by a baculovirus system (PharMingen) in Sf9 insect cells. The hIDE [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24] antibody was elicited by immunization with a synthetic peptide that corresponds to amino acids 7-24 (relative to the second ATG) of human insulysin that was coupled to keyhole limpet hemocyanin by a C-terminal cysteine residue (Pierce). Tissue homogenates were prepared in the 10 mM Tris⅐HCl, pH 7.8, lysis buffer that we have described previously (13), which contains protease inhibitors but no detergent, and centrifuged for 10 min at 10,000 ϫ g to remove debris.…”

“…Brains were extracted in 0.2% diethylamine in 50 mM NaCl and centrifuged at 20,000 ϫ g for 1 h at 4°C to remove insoluble material. Supernatant fractions were neutralized by the addition of 1 ⁄10 volume of Tris⅐HCl, pH 6.8, and analyzed by sandwich ELISA for A␤40 and A␤42 essentially as described previously (14,15) by using the BNT77͞BA27 and BNT77͞BC05 antibody systems to detect A␤40 and A␤42, respectively. We are grateful to Takeda (Osaka) for their generous gifts of BNT77, BA27, and BC05.…”

Alzheimer disease therapy: Can the amyloid cascade be halted?

“…Other examples of the complex effects of drugs on Aβ metabolism include the action of the PI3K inhibitor wortmannin (65). Wortmannin inhibits Aβ production, both in cells and in vivo, apparently by altering APP trafficking.…”