RESUMO
Consumption of caffeine, a non-selective adenosine A2A receptor (A2AR) antagonist, reduces the risk of developing Alzheimer's disease (AD) in humans and mitigates both amyloid and Tau burden in transgenic mouse models. However, the impact of selective A2AR blockade on the progressive development of AD-related lesions and associated memory impairments has not been investigated. In the present study, we removed the gene encoding A2AR from THY-Tau22 mice and analysed the subsequent effects on both pathological (Tau phosphorylation and aggregation, neuro-inflammation) and functional impairments (spatial learning and memory, hippocampal plasticity, neurotransmitter profile). We found that deleting A2ARs protect from Tau pathology-induced deficits in terms of spatial memory and hippocampal long-term depression. These effects were concomitant with a normalization of the hippocampal glutamate/gamma-amino butyric acid ratio, together with a global reduction in neuro-inflammatory markers and a decrease in Tau hyperphosphorylation. Additionally, oral therapy using a specific A2AR antagonist (MSX-3) significantly improved memory and reduced Tau hyperphosphorylation in THY-Tau22 mice. By showing that A2AR genetic or pharmacological blockade improves the pathological phenotype in a Tau transgenic mouse model, the present data highlight A2A receptors as important molecular targets to consider against AD and Tauopathies.
Assuntos
Transtornos Cognitivos/fisiopatologia , Hipocampo/fisiopatologia , Depressão Sináptica de Longo Prazo/fisiologia , Receptor A2A de Adenosina/metabolismo , Tauopatias/fisiopatologia , Antagonistas do Receptor A2 de Adenosina/farmacologia , Doença de Alzheimer/tratamento farmacológico , Doença de Alzheimer/fisiopatologia , Animais , Transtornos Cognitivos/tratamento farmacológico , Modelos Animais de Doenças , Ácido Glutâmico/metabolismo , Hipocampo/efeitos dos fármacos , Humanos , Depressão Sináptica de Longo Prazo/efeitos dos fármacos , Camundongos Transgênicos , Fosforilação , RNA Mensageiro/metabolismo , Receptor A2A de Adenosina/genética , Tauopatias/tratamento farmacológico , Técnicas de Cultura de Tecidos , Xantinas/farmacologia , Ácido gama-Aminobutírico/metabolismo , Proteínas tau/genética , Proteínas tau/metabolismoRESUMO
Maternal separation (MS) is an early life stress model that induces permanent changes in the central nervous system, impairing hippocampal long-term potentiation (LTP) and spatial working memory. There are compelling evidences for a role of hippocampal adenosine A(2A) receptors in stress-induced modifications related to cognition, thus opening a potential window for therapeutic intervention. Here, we submitted rats to MS and evaluated the long-lasting molecular, electrophysiological and behavioral impairments in adulthood. We then assessed the therapeutic potential of KW6002, a blocker of A(2A) receptors, in stress-impaired animals. We report that the blockade of A(2A) receptors was efficient in reverting the behavior, electrophysiological and morphological impairments induced by MS. In addition, this effect is associated with restoration of the hypothalamic-pituitary-adrenal axis (HPA-axis) activity, as both the plasma corticosterone levels and hippocampal glucocorticoid receptor expression pattern returned to physiological-like status after the treatment. These results reveal the involvement of A(2A) receptors in the stress-associated impairments and directly in the stress response system by showing that the dysfunction of the HPA-axis as well as the long-lasting synaptic and behavioral effects of MS can be reverted by targeting adenosine A(2A) receptors. These findings provide a novel evidence for the use of adenosine A(2A) receptor antagonists as potential therapy against psychopathologies.