INS and amyloidosis: Studies examining the effects of reduced insulin signalling on amyloid toxicity in APP over-expressing mice have reported either increased GSK-3 activity, reduced IDE activity and increased amyloidosis [68] or decreased GSK-3 activity, increased IDE expression and reduced amyloidosis [69] in the brain, suggesting an inverse correlation between GSK-3 and IDE activities in relation to Aβ metabolism.