Selective benefits of simvastatin in bitransgenic APPSwe,Ind/TGF-β1 mice

Cognitive and cerebrovascular deficits are 2 landmarks of Alzheimer's disease (AD) to target for effective therapy. Here, we evaluated the efficacy of simvastatin in bitransgenic A/T mice overexpressing a mutated form of the human amyloid precursor protein (APPSwe,Ind) and a constitutively active form of transforming growth factor-β1. These mice feature the AD amyloid beta (Aβ) and cerebrovascular pathology. Simvastatin significantly decreased insoluble Aβ peptide levels and Aβ plaque load despite no effect on β-site amyloid precursor protein-cleaving enzyme and Aβ-degrading enzyme neprilysin protein levels. However, simvastatin failed to improve spatial learning and memory deficits and the decreased baseline levels of the memory-related protein early growth response-1 (Egr-1) in the hippocampus CA1 area. The impaired hyperemic response to whisker stimulation in A/T mice was not improved with treatment, but simvastatin fully restored constitutive nitric oxide synthesis in vessel walls and exacerbated agonist-mediated dilatory deficits. These findings point to the efficacy of simvastatin on selective AD features in a complex model of the disease, likely reflecting the challenges faced by recent clinical trials in assessing statin efficacy.