Chronic administration of R-flurbiprofen attenuates learning impairments in transgenic amyloid precursor protein mice

Background: Long-term use of non-steroidal anti-inflammatory drugs (NSAIDs) is associated with a reduced incidence of Alzheimer's disease (AD). We and others have shown that certain NSAIDs reduce secretion of A beta 42 in cell culture and animal models, and that the effect of NSAIDs on A beta 42 is independent of the inhibition of cyclooxygenase by these compounds. Since A beta 42 is hypothesized to be the initiating pathologic molecule in AD, the ability of these compounds to lower A beta 42 selectively may be associated with their protective effect. We have previously identified R-flurbiprofen (tarenflurbil) as a selective A beta 42 lowering agent with greatly reduced cyclooxygenase activity that shows promise for testing this hypothesis. In this study we report the effect of chronic R-flurbiprofen treatment on cognition and A beta loads in Tg2576 APP mice. Results: A four-month preventative treatment regimen with R-flurbiprofen (10 mg/kg/day) was administered to young Tg2576 mice prior to robust plaque or A beta pathology. This treatment regimen improved spatial learning as assessed by the Morris water maze, indicated by an increased spatial bias during the third probe trial and an increased utilization of a place strategy to solve the water maze. These results are consistent with an improvement in hippocampal- and medial temporal lobe-dependent memory function. A modest, though not statistically significant, reduction in formic acid-soluble levels of A beta was also observed. To determine if R-flurbiprofen could reverse cognitive deficits in Tg2576 mice where plaque pathology was already robust, a two-week therapeutic treatment was given to older Tg2576 mice with the same dose of R-flurbiprofen. This approach resulted in a significant decrease in A beta plaque burden but no significant improvement in spatial learning. Conclusion: We have found that chronic administration of R-flurbiprofen is able to attenuate spatial learning deficits if given prior to plaque deposition in Tg2576 mice. Given its ability to selectively target A beta 42 production and improve cognitive impairments in transgenic APP mice, as well as promising data from a phase 2 human clinical trial, future studies are needed to investigate the utility of R-flurbiprofen as an AD therapeutic and its possible mechanisms of action.