Sonya Prescott

Bio: Sonya Prescott is an academic researcher from Mayo Clinic. The author has contributed to research in topics: Water maze & Morris water navigation task. The author has an hindex of 4, co-authored 5 publications receiving 260 citations.

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

Abstract: 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 Aβ42 in cell culture and animal models, and that the effect of NSAIDs on Aβ42 is independent of the inhibition of cyclooxygenase by these compounds. Since Aβ42 is hypothesized to be the initiating pathologic molecule in AD, the ability of these compounds to lower Aβ42 selectively may be associated with their protective effect. We have previously identified R-flurbiprofen (tarenflurbil) as a selective Aβ42 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 Aβ loads in Tg2576 APP mice. A four-month preventative treatment regimen with R-flurbiprofen (10 mg/kg/day) was administered to young Tg2576 mice prior to robust plaque or Aβ 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 Aβ 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 Aβ plaque burden but no significant improvement in spatial learning. 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 Aβ42 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.

Emergence of a Cue Strategy Preference on the Water Maze Task in Aged C57B6 × SJL F1 Hybrid Mice

Abstract: The effects of age on cue learning, spatial reference memory, and strategy preference were assessed in B6 × SJL F1 mice by using the Morris water maze. This mouse strain is of particular interest because it is the background strain for a common transgenic model of Alzheimer's disease, the Tg2576 mouse, which develops plaques and other neurobiological markers of pathology beginning at 8 mo and increasing in severity with advanced age. In the current study, 12- and 23-mo-old C57B6 × SJL F1 mice were serially trained in cue and place versions of the Morris water maze task. At the completion of training, mice received a strategy probe test in which place (hidden) and cue (visible) strategies were in competition. Cue and spatial learning ability was maintained between 12 and 23 mo of age; however, on the strategy preference probe test, the 23-mo-old mice exhibited a significant bias toward the selection of a cue strategy. There was no relationship between strategy preference in the probe test and spatial learning ability, but the 23-mo-old mice did exhibit a strong trend toward shorter latencies during visible platform training, possibly reflecting the enhanced function of striatal-based neural systems in aging. These data demonstrate that 23-mo-old C57B6 × SJL F1 mice are capable of effective place learning, but if a place strategy is pitted against the use of a cue strategy, the use of a cue strategy predominates in the aged mice. The strategy preference observed here may reflect an emergence of differential processing in underlying brain circuitry with age in the B6 × SJL F1 mouse strain.

Does neuroinflammation fan the flame in neurodegenerative diseases

Abstract: While peripheral immune access to the central nervous system (CNS) is restricted and tightly controlled, the CNS is capable of dynamic immune and inflammatory responses to a variety of insults. Infections, trauma, stroke, toxins and other stimuli are capable of producing an immediate and short lived activation of the innate immune system within the CNS. This acute neuroinflammatory response includes activation of the resident immune cells (microglia) resulting in a phagocytic phenotype and the release of inflammatory mediators such as cytokines and chemokines. While an acute insult may trigger oxidative and nitrosative stress, it is typically short-lived and unlikely to be detrimental to long-term neuronal survival. In contrast, chronic neuroinflammation is a long-standing and often self-perpetuating neuroinflammatory response that persists long after an initial injury or insult. Chronic neuroinflammation includes not only long-standing activation of microglia and subsequent sustained release of inflammatory mediators, but also the resulting increased oxidative and nitrosative stress. The sustained release of inflammatory mediators works to perpetuate the inflammatory cycle, activating additional microglia, promoting their proliferation, and resulting in further release of inflammatory factors. Neurodegenerative CNS disorders, including multiple sclerosis (MS), Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease (HD), amyotrophic lateral sclerosis (ALS), tauopathies, and age-related macular degeneration (ARMD), are associated with chronic neuroinflammation and elevated levels of several cytokines. Here we review the hallmarks of acute and chronic inflammatory responses in the CNS, the reasons why microglial activation represents a convergence point for diverse stimuli that may promote or compromise neuronal survival, and the epidemiologic, pharmacologic and genetic evidence implicating neuroinflammation in the pathophysiology of several neurodegenerative diseases.

Protein aggregation diseases: pathogenicity and therapeutic perspectives

Abstract: A growing number of diseases seem to be associated with inappropriate deposition of protein aggregates. Some of these diseases--such as Alzheimer's disease and systemic amyloidoses--have been recognized for a long time. However, it is now clear that ordered aggregation of pathogenic proteins does not only occur in the extracellular space, but in the cytoplasm and nucleus as well, indicating that many other diseases may also qualify as amyloidoses. The common structural and pathogenic features of these diverse protein aggregation diseases is only now being fully understood, and may provide novel opportunities for overarching therapeutic approaches such as depleting the monomeric precursor protein, inhibiting aggregation, enhancing aggregate clearance or blocking common aggregation-induced cellular toxicity pathways.

Using mice to model Alzheimer's dementia: an overview of the clinical disease and the preclinical behavioral changes in 10 mouse models.

Abstract: The goal of this review is to discuss how behavioral tests in mice relate to the pathological and neuropsychological features seen in human Alzheimer’s disease (AD), and present a comprehensive analysis of the temporal progression of behavioral impairments in commonly used AD mouse models that contain mutations in amyloid precursor protein. We provide a brief overview of neuropathological changes seen in AD brain, and some of the clinical neuropsychological assessments used to measure cognitive deficits. This is followed by a critical assessment of behavioral tasks that are used in AD mice to model the cognitive changes seen in humans. Behavioral tests discussed include spatial memory tests (Morris water maze, radial arm water maze, Barnes maze), associative learning tasks (passive avoidance, fear conditioning), alternation tasks (Y-Maze/T-Maze), recognition memory tasks (Novel Object Recognition), attentional tasks (3 & 5 choice serial reaction time), set-shifting tasks, and reversal learning tasks. We discuss the strengths and weaknesses of each of these tests, and how they may correlate with clinical assessments in humans. Finally, the temporal progression of both cognitive and non-cognitive deficits in ten AD mouse models (PDAPP, TG2576, APP23, TgCRND8, J20, APP/PS1, TG2576 + PS1(M146L), APP/PS1 KI, 5xFAD and 3xTg-AD) are discussed. Mouse models of AD and the behavioral tasks used in conjunction with those models are immensely important in contributing to our knowledge of disease progression, and are useful tools to study AD pathophysiology and the resulting cognitive deficits. However, investigators need to be aware of the potential weaknesses of the available preclinical models in terms of their ability to model cognitive changes observed in human AD. It is our hope that this review will assist investigators in selecting an appropriate mouse model, and accompanying behavioral paradigms to investigate different aspects of AD pathology and disease progression.

Effect of tarenflurbil on cognitive decline and activities of daily living in patients with mild Alzheimer disease: a randomized controlled trial.

Abstract: Context Amyloid-β peptide (Aβ 42 ) has been implicated in the pathogenesis of Alzheimer disease (AD). Tarenflurbil, a selective Aβ 42 -lowering agent, demonstrated encouraging results on cognitive and functional outcomes among mildly affected patients in an earlier phase 2 trial. Objective To determine the efficacy, safety, and tolerability of tarenflurbil. Design, Setting, and Patients A multicenter, randomized, double-blind, placebo-controlled trial enrolling patients with mild AD was conducted at 133 trial sites in the United States between February 21, 2005, and April 30, 2008. Concomitant treatment with cholinesterase inhibitors or memantine was permitted. Intervention Tarenflurbil, 800 mg, or placebo, administered twice a day. Main Outcome Measures Co-primary efficacy end points were the change from baseline to month 18 in total score on the subscale of the Alzheimer Disease Assessment Scale−Cognitive Subscale (ADAS-Cog, 80-point version) and Alzheimer Disease Cooperative Studies–activities of daily living (ADCS-ADL) scale. Additional prespecified slope analyses explored the possibility of disease modification. Results Of the 1684 participants randomized, 1649 were included in the analysis, and 1046 completed the trial. Tarenflurbil had no beneficial effect on the co-primary outcomes (difference in change from baseline to month 18 vs placebo, based on least squares means: 0.1 for ADAS-Cog; 95% CI, −0.9 to 1.1; P = .86 and −0.5 for ADCS-ADL; 95% CI, −1.9 to 0.9; P = .48) using an intent-to-treat analysis. No significant differences occurred in the secondary outcomes. The ADAS-Cog score decreased by 7.1 points over 18 months. The tarenflurbil group had a small increase in frequency of dizziness, anemia, and infections. Conclusion Tarenflurbil did not slow cognitive decline or the loss of activities of daily living in patients with mild AD. Trial Registration clinicaltrials.gov Identifier: NCT00105547