Stress acts cumulatively to precipitate Alzheimer’s disease-like tau pathology and cognitive deficits

Stressful life experiences are likely tiological factors in sporadic forms of Alzheimer’s disease (AD). Many AD patients hypersecrete glucocorticoids (GCs), and their GC levels correlate with the rate of cognitive impairment and extent of neuronal atrophy. Severity of cognitive deficits in AD correlates strongly with levels of perphosphorylated forms of the cytoskeletal protein TAU, an essential mediator of the actions of amyloid Beta (ABeta ), another molecule with a key pathogenic role in AD. Our objective was to investigate the sequential interrelationships between these various pathogenic elements, in particular with respect to the mechanisms through which stress might precipitate cognitive decline. We thus examined whether stress, through the mediation of GCs, influences TAU hyperphosphorylation, a critical and early event in the cascade of processes leading to AD pathology. Results from healthy, wild-type, middle-aged rats show that chronic stress and GC induce abnormal hyperphosphorylation of TAU in the hippocampus and prefrontal cortex (PFC), with contemporaneous impairments of hippocampus- and PFC-dependent behaviors. Exogenous GC potentiated the ability of centrally infused ABeta to induce hyperphosphorylation of TAU epitopes associated with AD and cytoplasmic accumulation of TAU, while previous exposure to stress aggravated the biochemical and behavioral effects of GC in ABeta-infused animals. Thus, lifetime stress/GC exposure may have a cumulative impact on the onset and progress of AD pathology, with TAU hyperphosphorylation serving to transduce the negative effects of stress and GC on cognition.Marie Curie Training FellowshipsEU CRESCENDO Consortium contract FP6-018652University College, London.Max Planck Society and European Union (EU) German-Portuguese Luso-Alemas Program and the EU CRESCENDO Consortium (Contract FP6-018652).German-Portuguese Luso-Alemas Progra

Land use and occupation analysis of Permanent Preservation Areas in Lavras County, MG Análise do uso e ocupação da terra em Áreas de Preservação Permanente no município de Lavras, MG

The Permanent Preservation Areas (PPAs) are considered essential for the maintenance of local biodiversity, so that your protection is regulated by the Brazilian legislation. This work had the objective of delimiting permanent preservation areas according to determinations of the current Brazilian environmental legislation, and identify the occurrence of conflict between the land use and legislation in Lavras county, MG, by combination of technologies of remote sensing and geographic information systems. The PPAs correspond to 42.33% of Lavras county's territory. The conflict between the land use and environmental legislation occurs in 63.48% of PPAs' territory, mainly corresponding to the pasture areas, bare soil and agriculture. The PPAs of tops of hills showed the highest conflicts with the legislation, with 48.48% of the territory occupied by pastures, and 13.62% by agriculture. The PPAs located in the surrounding of water courses and in the slopes with declivity higher than 45º presented 59.99% and 92.03%, respectively of the territory occupied by native vegetation of semi-deciduous forest and natural fields.<br>As Áreas de Preservação Permanente (APPs) são consideradas essenciais para a manutenção da biodiversidade local, de modo que a sua proteção é regulamentada pela legislação brasileira. Neste trabalho, objetivou-se delimitar as áreas de preservação permanente de acordo com as determinações da legislação ambiental brasileira vigente, e identificar a ocorrência de conflito entre o uso da terra e a legislação no município de Lavras, MG, mediante a combinação de tecnologias de sensoriamento remoto e sistemas de informações geográficas. As APPs correspondem a 42,33% do território do munícipio de Lavras. O conflito entre o uso da terra e a legislação ambiental ocorre em 63,48% do território das APPs, correspondendo principalmente as áreas de pastagem, solo exposto e agricultura. As APPs de topos de morro foram as que apresentaram maiores conflitos com a legislação, com 48,48% do seu território ocupado por pastagens e 13,62% ocupado pela agricultura. As APPs localizadas no entorno dos cursos d'água e nas encostas com declividade superior a 45º apresentaram, respectivamente, 59,99% e 92,03% do seu território ocupados por vegetação nativa de floresta semidecídua e campos naturais